0:09 NARRATOR: From the depths...
0:11 The giants are stirring...
0:13 MAN: This is almost as big as the boat
0:16 NARRATOR: Great whites in Hawaii...
0:18 MAN: I poked my head above the water and say,
0:20 "Hey guys there's a shark under your boat."
0:25 NARRATOR: Tigers in French Polynesia...
0:27 ANDY: Holy smokes.
0:28 A lot of sharks here.
0:29 NARRATOR: Possibly the largest ever caught on camera.
0:32 KORI: She's the biggest shark I've ever seen.
0:34 ANDREW: This thing is so big.
0:37 NARRATOR: What's behind these unbelievable encounters?
0:40 MARK: Deep Blue is probably the most famous shark in the
0:42 world besides Jaws.
0:44 NARRATOR: And can a tiger from Tahiti challenge
0:46 Deep Blue's legendary status?
1:03 Hawaii, a tropical paradise...
1:07 Known for white beaches, stunning scenery and
1:10 abundant marine wildlife.
1:18 Many shark species call these waters home.
1:22 Tiger sharks, hammerheads and oceanic white tips are common.
1:36 But it's extremely rare to see a great white...
1:40 On January 11, 2019, that was all about to change.
1:47 Everyone on the island of Oahu was talking about a huge
1:50 sperm whale carcass near the shore, attracting sharks.
1:57 An unusual sight for most.
2:01 But for wildlife photographer, Kimberly Jeffries, and boat
2:04 captain and diver, Mark Mohler, it sounded
2:07 like a chance to capture some amazing photos.
2:14 MARK: So we heard about the whale on the news.
2:16 We had reports of tiger sharks, oceanic white tips,
2:18 even hammerheads.
2:21 We wanted to get out as soon as we could and by the time we
2:23 made it out, the whale had already washed ashore
2:25 right here at Sand Island.
2:28 KIMBERLY: That's exactly where it was.
2:29 It was beached right there on the sand next to the rocks.
2:31 NARRATOR: Kimberly is a professional wildlife
2:33 photographer and conservationist.
2:39 Capturing amazing images, above and below the surface.
2:49 She and her boyfriend, Mark, dedicate as much of their time
2:51 as possible to their true passion, photographing and
2:55 studying animals in the water.
3:04 On January 12th, the Department of Land and Natural Resources
3:07 tows the dead whale back into the ocean.
3:13 KIMBERLY: I heard reports that they had dropped the whale
3:16 carcass eight miles offshore.
3:20 And I was like, "Let's go check it out."
3:24 NARRATOR: The next morning, Mark has other plans.
3:27 So Kim, along with two friends, Andrew Gray and
3:29 boat captain, Danny Roberts, set off in search of the carcass.
3:42 ANDREW: We got about 100 meters off the whale and
3:44 started gearing up.
3:48 NARRATOR: This is the moment they've been waiting for.
3:52 A chance to see whatever might be lurking under the water,
3:55 scavenging on the giant carcass.
3:59 ANDREW: And at that point, tiger sharks started swimming
4:02 up to our boat and checking us out.
4:06 So we knew it was gonna be a good dive.
4:15 NARRATOR: Andrew and Kim get in the water next to the
4:16 whale, excited to shoot.
4:24 CHRIS: Tiger sharks are probably the apex predator
4:26 around the Hawaiian Islands.
4:28 And they'll eat everything.
4:31 But, when a dead whale shows up, it's like ringing the
4:35 dinner bell for tiger sharks.
4:38 So, by and large, sharks don't consider humans food.
4:43 We are simply not on their menu.
4:45 But occasionally, people do get bitten and
4:47 we don't really know why.
4:48 One possibility is defense.
4:50 So, getting in the water around these sharks is
4:54 obviously a really cool experience, and the chances
4:57 of being bitten are obviously low, but we never advise that
5:00 for the public because that's a good way to
5:02 become an accident.
5:16 NARRATOR: An ominous quiet surrounds Kim and Andrew.
5:22 And the tiger sharks vanish.
5:31 After only minutes in the water, they discover the
5:33 tiger sharks had a very good reason to leave quickly.
5:43 ANDREW: A big shadow started appearing,
5:48 headed right towards us.
5:55 And I was thinking, what in the world is this?
5:58 'Cause it was way bigger than any shark I'd expect.
6:06 KIMBERLY: She was by far the biggest white shark I've ever
6:08 seen and, honestly, her girth was approaching
6:13 pilot whale size in just sheer mass.
6:19 ANDREW: This white shark swims right by Kim and I,
6:25 and heads directly towards the whale and took a big bite.
6:38 DANNY: There it is.
6:39 (whistles).
6:41 She is massive.
6:48 ANDREW: This thing is so big.
6:53 I would estimate this shark at six meters,
6:57 that's about 20 feet long.
6:59 NARRATOR: This seemed like the opportunity of a lifetime and
7:02 Kim didn't want Mark to miss it.
7:11 In French Polynesia, another megashark sighting...
7:16 but this time...it's a tiger.
7:20 And it may be the largest tiger shark
7:23 ever caught on camera.
7:25 Marine biologist Kori Burkhardt recorded this
7:28 female in 2018...
7:30 And named her Kamakai.
7:36 KORI: We have seen some really, really big sharks.
7:38 But none quite like her.
7:45 NARRATOR: The south Pacific is known to grow some of the
7:47 biggest tiger sharks in the world...
7:51 Bigger than Hawaii.
7:53 Bigger than Tiger Beach, Bahamas.
7:57 And French Polynesia may be attracting the biggest of them all.
8:03 Male tiger sharks can grow to a whopping 13 feet.
8:08 Females?
8:10 Even bigger.
8:13 And Kamakai: she's off the charts.
8:19 KORI: When we first met Kamakai it was really unexpected.
8:21 I've been diving with tiger sharks in multiple countries
8:24 and she is by far the biggest I've ever seen.
8:28 The smaller sharks took a, took a back seat to her for sure.
8:33 NARRATOR: Kori is five foot eight without her fins.
8:36 Based on that, Kamakai could be 16 feet!
8:44 Larger tigers are extremely rare...
8:49 The largest ever documented tallied 18 feet.
8:55 Her massive girth also sets her apart.
9:00 KORI: It's not just her length, but her width as well.
9:02 She can be 5 meters long, but when she's like 3 meters wide,
9:06 including her fins, like, that's insane.
9:10 NARRATOR: Kamakai could've been pregnant...
9:12 And, if so, are big sharks like her coming here to give birth?
9:19 Finding her again may unlock those secrets.
9:25 KORI: The biggest priority and the biggest goal would be to
9:26 see her physiological changes since the last time we saw her.
9:30 If she's skinnier, if she looks like she's a bit
9:32 smaller, maybe she did pup.
9:35 ANDY: Okay, here we go.
9:45 NARRATOR: Kori enlists cameraman and shark conservationist
9:47 Andy Casagrande to help with the search.
9:52 ANDY: She's got to be one of the biggest tiger sharks that
9:54 I have ever seen.
9:58 NARRATOR: Andy knows big sharks and knows how to be
10:00 in the water with them.
10:04 But he's never dived with the tigers of Tahiti.
10:09 ANDY: There's only a handful of spots in the world where
10:11 you get this sort of density of tiger shark action.
10:14 Super pumped. This is day one.
10:18 NARRATOR: Since the government banned shark fishing in
10:20 2 million square miles of the South Pacific in 2006...
10:25 These waters have become a vibrant Sharkapolis...
10:29 More than 20 different species.
10:32 With tigers at the top of the pecking order.
10:40 Less than a mile from the main island of Tahiti is a hot spot
10:44 known for big sharks.
10:50 KORI: You can see we have sharks here already,
10:51 just as we pull up.
10:52 Some black tip sharks, grey sharks, and hopefully
10:55 we can see some tigers here.
10:57 ANDY: Let's suit up.
11:03 NARRATOR: Andy and Kori decide to free dive,
11:06 using only snorkels.
11:10 Scuba gear could spook the sharks.
11:13 Their plan: to take pictures of as many dorsal fins
11:16 as they can.
11:19 Like a finger print, each is unique.
11:23 They'll use the fin shots to look for a match with Kamakai.
11:26 ANDY: Kori, I am going to follow your lead, eh?
11:28 KORI: Yeah.
11:41 ANDY: Wow, there's a lot of sharks here.
11:51 I mean, I'm gonna follow you.
11:52 Anytime you dive down, I'll follow you.
11:58 KORI: Ka ka ka kay!
12:01 NARRATOR: Kori's underwater call lets Andy know there's a
12:03 tiger shark close by.
12:06 KORI: Ka ka ka kay.
12:16 NARRATOR: Andy goes after a dorsal I.D. shot.
12:23 The underbelly is smooth, no claspers.
12:28 The dorsal fin shows mating scars.
12:32 She's a female.
12:36 ANDY: Kori, on the next one, if she comes by, can you
12:40 dive down and try to get closer?
12:42 KORI: Yeah.
12:44 NARRATOR: To measure the shark Andy will use Kori as a comparison.
12:47 But first, she must get close.
12:51 KORI: Ka ka ka kay.
12:58 NARRATOR: Kori is a master free diver.
13:02 She dives 60 feet deep and holds her breath for up to four minutes.
13:16 She makes no noise at all.
13:26 Now the tiger comes right in.
13:37 It's bold.
13:42 Maybe too bold.
13:47 KORI: Ka ka ka ka kay!
13:50 Ah!
13:54 NARRATOR: A big Tahitian tiger shark goes eye-to-eye with
13:57 marine biologist Kori Burkhardt.
14:15 NARRATOR: Kori must swim close to get a size comparison.
14:34 She's big, 12 or 13 feet.
14:43 But Kamakai is around 16 feet,
14:47 and the dorsal fin isn't a match.
14:52 So this is not Kamakai.
14:58 ANDY: Wow, that was incredible.
15:03 NARRATOR: But it is another large female tiger shark.
15:07 And it supports findings that bigger sharks now thrive
15:09 in Polynesian waters.
15:15 Andy and Kori aren't ready to give up yet,
15:18 Kamakai could be out here too.
15:26 In Hawaii, divers Kim and Andrew are experiencing a
15:30 close encounter with a massive great white...
15:36 And their friend Mark races to meet them.
15:44 KIMBERLY: I've been to Guadalupe and I've seen quite
15:46 a few white sharks in person, and this was by far the
15:50 largest that I've ever seen.
15:58 It was really surreal.
16:00 Her pace was not what you would imagine.
16:03 She was really just very stately in her
16:07 movement and manner.
16:14 ANDREW: She stuck around for about half an hour,
16:16 circling the whale and feeding.
16:21 And then she dove straight down under the whale and
16:23 I thought, she's gone, this is it,
16:27 Mark's not gonna get to see her.
16:31 I know how rare white shark sightings are in Hawaii.
16:37 CHRIS: Typically, white sharks are not seen very frequently
16:39 in the Hawaiian Islands.
16:42 There was shark control programs that were done in
16:44 the '50s, '60s and '70s and I think they caught four total,
16:48 out of thousands and thousands of sharks that were caught.
16:52 So while we know white sharks come to the Hawaiian Islands,
16:55 they don't come in huge numbers like we see off the
16:57 coast of California or Mexico, South Africa or Australia.
17:05 ANDREW: Tiger sharks started moving in and feeding on the
17:07 whale, so I figured the white shark was definitely gone.
17:13 NARRATOR: Mark is finally in the water.
17:16 Suddenly, the tiger sharks disappear again.
17:22 And it's quiet.
17:24 Until, out of the depths, a giant emerges, and
17:28 it's heading straight for Mark's boat.
17:35 TIM: It's coming right here! Holy!
17:44 MARK: The shark came up to the prop and I thought it was
17:46 gonna bite my prop on my boat.
17:55 NARRATOR: But the great white shark decides rotting whale
17:57 meat is a better meal and returns to the carcass.
18:04 As the great white continues to chow down,
18:06 the divers capture amazing footage.
18:09 MARK: This was my first experience with white sharks.
18:12 Couldn't believe what I was seeing, it was
18:13 a really special experience.
18:18 NARRATOR: The shark makes the most of this lucky break,
18:20 filling her immense body with as much whale meat as possible.
18:28 With such a big belly and voracious appetite,
18:30 could she be eating for two?
18:33 Could she be pregnant?
18:35 CHRIS: It's possible that she's been out for a year and a half.
18:38 She could be carrying a womb full of close-to-term pups
18:41 and getting ready to make her migration back to
18:43 coastal California or Mexico to give birth.
18:48 Or the other possibility is she could just have
18:49 a belly full of whale.
18:53 It's thought that a white shark could take out over
18:55 400 pounds of whale meat in a sitting.
19:09 NARRATOR: Finally, the white shark has eaten her fill and
19:12 dives down deep, disappearing.
19:16 ANDREW: We stuck around for a while, hoping she'd come back.
19:19 The tiger sharks moved in and we decided to call it a day.
19:23 We were exhausted.
19:25 MARK: It was an incredible day on the water.
19:29 NARRATOR: But who is this giant from the deep?
19:32 Kim hopes her photos will solve the mystery.
19:36 KIMBERLY: There have always been stories about
19:37 white sharks in the Hawaiian Islands, but there haven't
19:39 been very many documented instances of them.
19:44 We had ID shots and video and it was more than enough
19:48 to present to at least the scientific community for identification.
20:01 NARRATOR: In Tahiti, Kori and Andy decide to search
20:03 for Kamakai where Kori first encountered the massive tiger shark.
20:13 A fisherman alerted Kori to the location.
20:17 KORI: He called us and said that he had this crazy crazy
20:21 spot where they've had this huge influx of tiger sharks.
20:27 NARRATOR: It was flush with tigers, but finding one like
20:30 Kamakai there was a huge surprise.
20:37 The spot is 220 miles north, inside an atoll, just a few
20:41 day's swim for a fast-cruising tiger.
20:50 It's the largest atoll in the Polynesian group.
20:55 A ring of coral reef makes a lagoon 50 miles long,
20:58 20 miles wide.
21:00 KORI: It's massive.
21:02 One of the biggest in the entire world and its
21:04 protected, so it's like getting a chance to be in the
21:06 open ocean but, with a little bit of barrier around you.
21:09 And there's only two ways to get in and out.
21:17 NARRATOR: Kori and Andy head in with Taurama Sun,
21:19 the fisherman who first called Kori.
21:23 He's been fishing inside the lagoon for his entire life.
21:26 And the tiger sharks are new.
21:31 TAURAMA: We was really surprised to see many many
21:33 sharks like this.
21:35 ANDY: So many tiger.
21:36 TAURAMA: So many tigers, yeah.
21:39 NARRATOR: Fishing in the lagoon has always attracted sharks...
21:44 But the increased sightings here suggest
21:46 the government's protection measures are paying off.
21:53 ANDY: Hey.
21:55 Wow, looks like we've got at least three tigers right at
21:59 the back of the boat.
22:01 There's another one at the front and another one over there.
22:14 Thank you.
22:15 Got it.
22:28 NARRATOR: Tiger sharks are normally solitary.
22:31 But here they're everywhere.
22:34 And something about them is distinct.
22:40 ANDY: Holy smokes, a lot of sharks here.
22:43 KORI: So many tigers, they are everywhere.
22:44 This is amazing!
22:49 NARRATOR: All of these tiger sharks are less than nine feet,
22:53 immature juveniles and sub adults.
22:58 But what is it about the lagoon that attracts younger tigers?
23:03 And what was a mature shark like Kamakai doing here?
23:10 ANDY: So this thing is just a super basic, non-invasive,
23:12 spring-loaded fin cam system.
23:15 NARRATOR: Andy hopes this tool can help provide answers.
23:19 ANDY: We are tracking with it and seeing what it sees.
23:20 And we're basically diving into the secret life of the shark.
23:25 NARRATOR: Two sharks with cameras can scout a much
23:27 bigger section of the giant lagoon than a couple of divers.
23:34 KORI: So if we can see what they are doing and
23:35 why they are doing it,
23:36 I think that's really helpful for the behavior.
23:39 NARRATOR: With other species like bull sharks and great whites,
23:43 the young segregate themselves so they
23:46 aren't attacked and eaten by the adults.
23:50 Maybe that's what's happening here.
23:54 PIERRICK: They come all at the same time...
23:56 NARRATOR: Pierrick Seybald is Kori's safety diver.
23:59 She'll need him for this dive.
24:01 PIERRICK: Like a little gang.
24:03 NARRATOR: She's going to try and attach the cameras to the
24:04 tiger sharks, by hand.
24:09 KORI: Andy, I am going to go ahead and jump in.
24:19 NARRATOR: These young tigers are more unpredictable than adults.
24:29 ANDY: One coming up behind you.
24:34 NARRATOR: Kori wants to start with a small juvenile.
24:38 She makes her move.
24:55 ANDY: Got it!
25:01 NARRATOR: They still need a second volunteer.
25:06 This one's a sub-adult.
25:14 KORI: That looks bigger than all of them.
25:15 Want me to go?
25:16 ANDY: Let's do it.
25:32 NARRATOR: Kori's two for two.
25:37 ANDY: Nice work!
25:42 NARRATOR: But this camera shark moves in for a close up.
25:54 (grunting).
25:57 The first thing it films is a bee line right for the safety diver.
26:07 Pierrick rubs receptors located in her snout.
26:15 He wants to calm her down.
26:24 But it's clear.
26:28 This young tiger doesn't want calm.
26:32 It wants a diver.
26:40 NARRATOR: In Hawaii, Kim Jeffries couldn't wait
26:43 to find out more about the massive great white
26:46 feasting on a sperm whale carcass.
26:49 KIMBERLY: When I got home, the first thing I did was download
26:51 the images and videos and I immediately reached out to
26:54 my friend, George, who I've worked with in the past
26:57 to identify white sharks in Guadalupe.
27:02 NARRATOR: Using images stored in a database, researchers
27:05 have a system to identify individual sharks that visit
27:08 Guadalupe Island in Mexico,
27:11 a great white hotspot in the Pacific.
27:14 Currently, 261 unique white sharks have been identified.
27:23 CHRIS: So it turns out white sharks have unique markings
27:25 that enable us to identify them, based on the white and
27:28 gray markings along the side of their body, along their
27:30 gills, along their tail and of course...
27:32 Over the years, they acquire unique scars.
27:35 During mating they quite often bite each other.
27:38 In addition, they'll compete with each other over food or
27:40 sometimes the things that they eat will fight back.
27:43 So those unique scars and unique markings have been used
27:46 by researchers to identify individuals.
27:52 NARRATOR: With the help of the Marine Conservation Science Institute,
27:55 shark photographer George Probst makes
27:57 a startling conclusion.
27:59 KIMBERLY: He responded that we had possibly seen Deep Blue,
28:04 to which I said, "You're off your rocker, George and
28:07 you've seen too many white sharks at this point."
28:11 NARRATOR: In 2013, off the coast of Guadalupe Island, Mexico,
28:15 photographer, Michael Maier, films possibly the
28:18 largest great white shark ever caught on camera.
28:22 Local shark researcher, Mauricio Hoyos, names her Deep Blue.
28:27 Experts at the time estimated her to be 20 feet long
28:31 and 50 years old.
28:38 MARK: I got goose bumps from hearing that news.
28:41 Deep Blue is probably the most famous shark in the
28:44 world besides Jaws.
28:49 KIMBERLY: When George told me that it was Deep Blue, I was
28:51 really shocked because I've been to Guadalupe and I went
28:55 in the season where you see the big females.
28:58 But nothing that I'd seen even compared to that legend of
29:01 Deep Blue.
29:06 NARRATOR: Using photos like Kim's, scientists can now
29:10 better calculate Deep Blue's size.
29:17 With Kim as a reference,
29:19 Deep Blue is at least 20 feet long.
29:22 But what was Deep Blue doing here in Hawaii in 2019,
29:27 six years after being spotted off of Guadalupe Island.
29:33 CHRIS: You know, 25 years ago, if you'd asked any shark
29:36 biologist what kind of shark we thought a white shark was,
29:38 we would have said a coastal shark.
29:41 And it wasn't until the advent of some of the technology that
29:43 we use, like satellite tags, that literally changed our
29:46 minds overnight of white sharks from being a coastal
29:49 species, at least in the Northeast Pacific, to being
29:53 an open ocean species.
30:02 Most of the sharks that have been tagged and tracked,
30:04 some have been tagged on the Farallons,
30:06 some have been tagged in Guadalupe.
30:08 We see very little movement of those sharks between
30:10 those two locations.
30:12 They tend to all go out to the same place, kind of in the
30:14 middle of the Pacific.
30:16 Researchers coin this area, kind of halfway between Hawaii
30:19 and Baja, the shared offshore foraging area.
30:30 NARRATOR: Footage of great whites in Hawaii is extremely rare.
30:34 But deep, submersible missions have captured something
30:37 surprising that could be a clue why few people see the
30:40 great whites that make the journey here.
30:43 MAN: Holy! WOMAN: Ooh!
30:46 MAN: Huge shark. Look at this guy.
30:49 CHRIS: ROV and submersible studies have sighted
30:51 white sharks as deep as 1000 feet around Hawaiian Islands.
30:56 MAN: It is a great white. That is a great white shark.
30:58 MAN 2: No way.
30:59 MAN: That is huge.
31:01 Look at that, a 12-15 foot great white.
31:04 CHRIS: So it's very likely that white sharks are present here,
31:07 they're just so deep we rarely see them.
31:11 NARRATOR: If Deep Blue swam from Guadalupe Island to Hawaii,
31:14 she would have covered over 2,400 miles,
31:18 a remarkable distance.
31:20 But, as Kim, Mark and Andrew were about to discover,
31:22 Deep Blue wasn't alone.
31:34 NARRATOR: The search for a mega tiger shark named Kamakai
31:37 has led to a vast Polynesian lagoon full of
31:40 juvenile tiger sharks.
31:42 One of them is after the dive team.
31:58 Young tigers can be very erratic.
32:02 The team members decide not to push their luck.
32:05 ANDY: Get on the boat.
32:15 NARRATOR: Kori and Andy successfully deployed two
32:17 fin cams to monitor behavior here.
32:21 Now they must wait.
32:25 KORI: Phew. ANDY: Wicked.
32:29 NARRATOR: The fin cam is designed to release
32:31 after a few hours.
32:35 A tiger shark can cover a lot of ground in that time;
32:40 they've been known to swim 60 miles a day.
32:45 The footage should give Kori and Andy an idea of what the
32:48 young tigers are doing in the lagoon.
32:53 And, possibly, what brought Kamakai here.
32:58 Three hours later.
33:00 They get a signal on their receiver.
33:04 ANDY: Kori, it sounds like the camera has popped up
33:05 way out there, like way outside the lagoon.
33:09 But in the deep water, yeah?
33:11 KORI: Yeah.
33:12 NARRATOR: The first camera they detect is from the
33:14 bigger tiger: the sub-adult.
33:18 Looks like the camera came off as she headed
33:19 out of the lagoon.
33:22 ANDY: Alright. Nice work!
33:26 NARRATOR: But the smaller female dropped hers
33:29 inside the lagoon.
33:31 ANDY: Nice.
33:33 Two fin cams deployed.
33:35 Two retrieved.
33:36 Let's check the footage.
33:42 NARRATOR: In Hawaii, Kim, Mark, and Andrew have just had an
33:46 encounter with possibly the world's largest great white.
33:50 And news of another has them itching for more.
33:55 KIMBERLY: After learning about the new sighting, it really
33:56 pushed us to go out the next day.
34:02 NARRATOR: But the next morning, Mark has to work.
34:07 So Kim and Andrew head out in Kim's boat, Rubber Ducky.
34:13 And they find the whale quickly.
34:18 ANDREW: There was already a boat out there with five divers.
34:21 KIMBERLY: And they said they hadn't seen anything except
34:23 for tiger sharks.
34:27 NARRATOR: Andrew gets in the water right away,
34:31 and Kim takes a moment to relieve herself.
34:34 ANDREW: Kim is hanging off the side of her boat,
34:37 taking a leak, and I see a massive white shark swimming in,
34:41 directly underneath her.
34:53 I poke my head above the water and say,
34:55 "Hey, guys, there's a shark under your boat."
34:58 KIMBERLY: And I said, "Yeah, yeah, whatever, no big deal."
35:00 'Cause they'd only seen tiger sharks in the area until then.
35:05 NARRATOR: But this isn't a tiger shark, it's a great white.
35:10 A very large great white.
35:13 KIMBERLY: I pushed myself back into the boat really quickly,
35:15 grabbed my mask and my camera, put my fins on and
35:19 rolled back into the water.
35:23 I wasn't sure whether or not it was Deep Blue or not.
35:27 She was incredibly huge and just incredibly majestic.
35:34 She was a little bit more inquisitive than Deep Blue
35:37 which was one of the first indicators to me that
35:39 something was slightly different.
35:42 NARRATOR: It was indeed a brand new 18-foot female that
35:45 had never been recorded before.
35:49 KIMBERLY: I got to name it, as a result of taking pictures
35:53 and presenting it to be identified, and so I named her
35:57 Haole Girl as a tribute to the Hawaiian culture and
36:02 a white visitor to our islands.
36:06 It's possible that this shark has never encountered humans before.
36:09 So I think she was just really curious and
36:12 wanted to check us out.
36:14 ANDREW: This shark was especially interested in our boat.
36:17 It's possible that she thought the boat was a
36:19 chunk of the whale.
36:24 KIMBERLY: So, the boat that we were in is Rubber Ducky.
36:26 It's my boat, it's about 17 feet long.
36:33 ANDREW: It has sponsons around the side of it that are filled
36:37 with air and a hard hull.
36:40 This shark would repeatedly come up and nose the sponsons.
36:47 KIMBERLY: She gave a little test nibble on the starboard
36:49 side and that's when she popped one of the tubes.
36:58 ANDREW: We hear air hissing out.
36:59 It must have been just a couple minutes before she came
37:02 back to the same area, took a nice bite and
37:07 made a big gash right into it.
37:10 KIMBERLY: My boat is sinking.
37:19 MARK: 10:00 on Tuesday morning, I get a text message
37:23 from Kim that says,
37:26 "Shark bit the boat. We're fine, come out now!!!"
37:34 KIMBERLY: Mark came out in about an hour.
37:39 He did bring some tie-downs to strap the tube in place.
37:46 MARK: So, not long after I had checked their boat out, we saw
37:49 that the shark was coming in behind the boat that I brought
37:52 out and that's when I got the really cool picture from the
37:56 surface of Kim in the water right in front of Haole Girl.
38:08 NARRATOR: Mark captured incredible photos of Kim and
38:10 the shark, really showcasing her size.
38:22 ANDREW: After swimming around us for hours,
38:28 she eventually took off.
38:32 CHRIS: Finding one white shark on a whale, sure.
38:34 Getting three large female white sharks on a whale,
38:37 that's different, right?
38:38 That means those sharks had to be close enough in the
38:41 vicinity to, number one, detect the odor of that whale
38:43 and then also it might mean that these sharks
38:46 are traveling together.
38:47 It's something we've never really been able to
38:49 study or understand.
38:55 NARRATOR: In French Polynesia, Kori and Andy hope fin cam
38:58 footage from two juvenile tiger sharks may finally lead
39:01 them to the mega tiger Kamakai.
39:05 ANDY: What is that?
39:06 KORI: That's a fish.
39:07 NARRATOR: The bigger shark headed out.
39:11 ANDY: Looks like she's heading deeper.
39:14 NARRATOR: At around eight feet long, and at least
39:16 four years old, she's approaching adulthood.
39:20 And heading outside the lagoon.
39:25 ANDY: Cool.
39:27 NARRATOR: It's more dangerous out here.
39:31 Hammerheads patrol these waters.
39:38 Adult hammerheads are cannibals,
39:41 known to eat smaller sharks.
39:43 Like young tigers.
39:49 Kori and Andy came to the lagoon in search of Kamakai.
39:54 So far there's no sign of her.
39:57 But these teen tigers may hold clues to
39:59 what brought Kamakai here.
40:04 ANDY: There's like one, two.
40:07 This little one is obviously encountering
40:08 other juveniles here.
40:10 That one right there, that one right there.
40:11 That is a rad shot of that tiger cruising
40:14 amongst its friends.
40:16 They're not being aggressive.
40:18 KORI: They don't seem to be really in competition.
40:21 NARRATOR: Tiger shark pups are much smaller when
40:24 they're born: 20 to 30 inches long and very vulnerable.
40:31 Maybe these young sharks were born here, or nearby...
40:35 And the lagoon serves as a sanctuary.
40:40 ANDY: If they swim out the pass, they are basically
40:41 subject to being predated on by big sharks.
40:45 KORI: I think this is where they kind of learn to be
40:47 sharks and once they're big enough to get past that
40:49 learning curve and it's not as dangerous for them to go out.
40:53 NARRATOR: The strong currents in and out of
40:54 the lagoon provide a constant supply of food.
40:58 And the shallower water keeps out the larger hammerheads.
41:03 ANDY: If I was a little tiger shark, I would hang out
41:04 in this lagoon too.
41:05 It's like the perfect safe zone,
41:07 where there is food, safety, friends.
41:09 It makes perfect sense.
41:14 NARRATOR: The pieces of the puzzle may be coming together.
41:19 Huge females gather off the island of Tahiti,
41:22 showing mating scars.
41:26 Maybe Kamakai was so big because she was pregnant.
41:31 KORI: That could be one reason that she was so wide.
41:34 It's very possible that she was coming in dropping those
41:36 babies off and heading back out.
41:40 NARRATOR: A lagoon full of young tiger sharks.
41:43 Which suggests a rare pupping ground may be nearby.
41:51 No Kamakai, but evidence of stages in the tiger shark life cycle.
42:01 14 years after protection, the waters off French Polynesia
42:05 have transformed into a big tiger paradise.
42:17 A safe haven where a shark like Kamakai can birth a
42:21 new generation of mega tiger sharks.
42:29 Like French Polynesia, environmental protections
42:32 in Hawaii seem to be making an impact.
42:35 Since Deep Blue and Haole Girl,
42:39 even more great white sightings have occurred.
42:43 CHRIS: The white shark population has probably been
42:46 reduced for over 100 years, due to loss of their favorite
42:49 food and over-hunting.
42:52 So now that white sharks are coming back, we don't know
42:54 whether the patterns we're seeing now are the patterns
42:58 that were always there or whether they're new patterns
43:00 as the population grows.
43:03 NARRATOR: Did the team film the world's biggest known
43:05 great white shark?
43:07 Quite possibly.
43:09 But they definitely encountered two of the largest
43:11 white sharks ever recorded in Hawaii, giving hope that an
43:15 even larger shark might be hiding somewhere in the deep.
43:21 ANDREW: I know how rare white shark sightings are in Hawaii
43:26 and this experience was absolutely incredible.
43:29 By far the best I've ever had in the water.
43:37 KIMBERLY: This was one of the most amazing experiences I've
43:40 ever had in my life.
43:41 There have always been legends of white sharks in Hawaii but
43:44 to actually have gotten the chance to see one
43:46 and then ultimately getting to name one,
43:49 was just absolutely incredible.
44:06 NARRATOR: Locals are still talking about
44:08 what happened here last spring.
44:12 It was a perfect day for fishing.
44:18 MAN (off screen): Whoo! That's a big one.
44:21 NARRATOR: But below the surface,
44:23 two heavyweights of the shark world
44:26 were on a collision course.
44:29 MAN (off screen): That's insane!
44:32 NARRATOR: It's a rare face-off
44:33 between a bull shark and a great hammerhead
44:37 prompting a team of experts
44:39 to dig deeper into the encounter...
44:41 MAN: One, two, three.
44:44 NARRATOR: ...in the hope to uncover surprising behaviors...
44:49 VALERIE HAGAN: We might have a predation.
44:51 DR. YANNIS PAPASTAMATIOU: I have no idea what is going on here.
44:53 NARRATOR: ...and come face-to-face
44:55 with two of the biggest...
44:58 MAN:
44:59 NARRATOR: ...baddest...
45:00 DR. MIKE HEITHAUS: Look out! Look out!
45:01 NARRATOR: ...super predators on the planet.
45:04 But which one takes the crown?
45:14 Several people captured the event
45:16 in the spring of 2021.
45:18 MAN (off screen): That's insane!
45:20 NARRATOR: The video quickly went viral.
45:23 A bull shark chases a monster great hammerhead
45:25 and pins it to the beach.
45:28 There's no escape.
45:32 The bull shark circles...
45:36 followed by a second.
45:39 Then the hammerhead is ripped to pieces.
45:47 Marine biologist Dr. Mike Heithaus was floored.
45:52 DR. HEITHAUS: I've never seen anything like this.
45:55 A lot of times, we've got these big, top predators
45:59 but they don't usually
46:01 pay much attention to one another.
46:03 In this case, it was a head-to-head battle.
46:06 We had a winner and a loser.
46:11 NARRATOR: An encounter of this magnitude is rare.
46:14 It provides the perfect opportunity
46:16 to understand how these apex predators
46:18 stack up in a one-on-one battle.
46:23 Fishing Charter Captain Mike Myers saw the whole thing.
46:28 CAPT. MIKE MYERS (off screen): Oh, my gosh.
46:29 DR. HEITHAUS: Can you walk me through what happened that day?
46:33 CAPT. MYERS: I had clients onboard.
46:35 I just saw it.
46:36 "Oh, my gosh, a huge hammerhead."
46:39 DR. HEITHAUS: How big do you think that hammerhead was?
46:41 CAPT. MYERS: I'm estimating somewhere around 12 to 13 foot.
46:46 They kinda swam up towards the beach
46:48 and people were over there screaming and hollering
46:51 because he kept beaching himself.
46:54 Every once in a while, one of the bull sharks
46:55 would come up and grab 'em by the tail
46:57 and jerk it and then swim up real fast.
47:01 And all of a sudden, you look down...
47:05 and then...
47:09 the sand just exploded.
47:11 We looked as hard as we could
47:14 after that whole mess happened.
47:15 There wasn't a fin on the ground.
47:16 There wasn't anything in the water.
47:18 He was gone.
47:19 DR. HEITHAUS: You've been out here a long time.
47:22 CAPT. MYERS: I've seen a lot of bizarre things
47:24 with these sharks over the years.
47:25 Oh, my gosh.
47:27 I've never seen anything close to that.
47:32 NARRATOR: Big sharks are known to attack
47:33 and eat smaller sharks.
47:36 But these two apex predators are powerful equals.
47:44 The hammerhead, sleek, massive,
47:47 and can turn on a dime.
47:49 In a one-on-one fight, they are fearsome opponents.
47:53 Great hammerheads can grow to be nearly 20 feet long,
47:57 almost twice as big as the bull shark.
48:00 Bull sharks may be in a different weight class,
48:03 but they pack a lot of punch for their size.
48:06 Stocky with a superior jaw strength.
48:09 Bull sharks have a bad reputation
48:11 for a good reason.
48:15 DR. HEITHAUS: Lots of questions come out of this video.
48:17 CAPT. MYERS (off screen): Oh, my gosh.
48:19 DR. HEITHAUS: They're both top predators.
48:20 You don't really think about one going after the other.
48:23 So to see them battling it out
48:26 is incredibly unique.
48:30 If these sharks are going head-to-head,
48:32 who's gonna come out on top?
48:37 When top predators battle it out with one another
48:40 or have interactions
48:41 that can cascade through the rest of the ecosystem.
48:44 So learning about the interactions
48:45 among top predators is really important.
48:51 NARRATOR: To investigate this surprising new dynamic,
48:53 Mike has assembled a team of experts.
48:58 DR. HEITHAUS: We're gonna try to get to the bottom of this
48:59 by first studying bull sharks and great hammerheads separately
49:03 and then going to a place where they might come together
49:05 to see if it's a collision or if they go their separate ways.
49:09 NARRATOR: First up, the great hammerhead.
49:14 Team member Erin Spencer
49:16 leads this part of the investigation.
49:19 ERIN SPENCER: They're one of the most recognizable sharks in the ocean.
49:21 When you see that cephalofoil
49:23 and just see the eyes and how big that head can get,
49:27 it really kinda takes your breath away.
49:30 NARRATOR: Famous for its elongated head extensions
49:32 called cephalofoils,
49:34 the great hammerhead has an advantage
49:36 over the bull shark
49:37 in its uniquely positioned eyes.
49:40 With a nearly 360-degree field of vision,
49:44 it has the best depth perception of any shark,
49:47 giving it pinpoint accuracy on attack.
49:50 Its wide head also contains more electrosensory receptors
49:54 than other sharks.
49:57 SPENCER: All of these pieces come together to make them
50:00 as good a predators as they are.
50:04 But because they're so big and wide ranging,
50:07 they're really difficult to study.
50:10 We use something called biologgers
50:12 which are essentially
50:13 animal mounted data collecting devices.
50:16 And the biologgers are like Fitbits for sharks.
50:20 DR. HEITHAUS: So by putting that on the back of the shark,
50:22 it can give you a three-dimensional path
50:24 of how it's moving through its environment,
50:26 how it's speeding up, slowing down,
50:29 pitching, rolling.
50:33 We just gotta get out there, catch a hammerhead
50:35 and get one of our accelerometer tags on its dorsal fin.
50:41 NARRATOR: While Erin readies a hammerhead 3D biologger,
50:44 Mike heads back out to the scene of the crime...
50:48 to look for more clues with Captain Myers.
50:53 For a few months a year,
50:55 this relatively deep channel west of Fort Myers
50:58 is a fisherman's paradise.
51:00 MAN: I told you it's a big one.
51:03 DR. HEITHAUS: It is packed full of these giant fish called tarpon.
51:07 They could be more than 200 pounds
51:08 and they're one of the world's most coveted game fish.
51:13 NARRATOR: As the water warms each spring,
51:16 thousands upon thousands of tarpon
51:18 migrate north to Boca Grande to spawn.
51:23 Anglers come from all over the world to try their luck.
51:27 As they fight these mammoth fish,
51:29 bull sharks and hammerheads cross paths
51:31 in their quest for easy prey.
51:37 Over the years, Captain Myers
51:38 who captured the video of the attack
51:40 has observed both predators on a daily basis.
51:44 DR. HEITHAUS: Have you ever seen the bull sharks or hammerheads
51:47 go after tarpon that aren't hooked up?
51:49 -So-- -CAPT. MYERS: Oh, God, yeah.
51:51 The bull sharks will get around these schools.
51:53 That's 10,000 fish running up and down this beach.
51:57 I have seen numerous, numerous times
51:59 the hammerheads come in.
52:00 People don't realize how agile that fish actually is.
52:04 NARRATOR: What Captain Myers recalls next intrigues Mike.
52:08 CAPT. MYERS: And what's really cool,
52:10 when a hammerhead comes, bulls aren't around.
52:13 They don't want nothing to do with it.
52:15 NARRATOR: It contradicts the behavior
52:17 Captain Myers captured on video a year earlier.
52:20 CAPT. MYERS: The hammerheads come in
52:21 and there's no more bull sharks.
52:24 What I saw floored me.
52:28 NARRATOR: The team decides to deploy
52:29 the hammerhead tag right here in Boca Grande Pass.
52:34 But the next morning, Mike gets some bad news.
52:37 (sighs)
52:39 DR. HEITHAUS: Unfortunately, we just heard
52:40 from Erin and she's been exposed to COVID,
52:42 so she can't make it out today.
52:44 But she's programmed the tag for us and we've got a crew.
52:47 So we're gonna go out and try to catch a great hammerhead.
52:49 Anything we need to be thinking of to get this on for you?
52:52 Not having her on the boat is gonna be a big challenge
52:55 'cause that's one less experienced person
52:57 to handle a shark.
52:58 But hopefully we can get it done and get some great data for.
53:01 NARRATOR: Mike will work with
53:03 Mote Marine Laboratory biologists
53:05 Valerie Hagan and Jack Morris
53:07 to see if they can get the tag on a hammerhead by themselves.
53:12 HAGAN: Jack and I work with one another
53:13 for most of our field work.
53:16 JACK MORRIS: That's fishing, right?
53:17 So you always come up with the expectation
53:18 that you hope you're gonna get what you want.
53:20 And when you do, it's amazing.
53:23 NARRATOR: They set ten fishing lines
53:24 along the mouth of Boca Grande Pass,
53:27 its prime hammerhead territory.
53:30 DR. HEITHAUS: That is a piece of stingray.
53:33 And a hammerhead loves stingrays.
53:36 They'll actually use their head
53:39 to pin 'em to the bottom
53:40 to hold them down so they can get a bite.
53:43 NARRATOR: While they wait for a catch,
53:45 Mike preps Erin's 3D biologger.
53:47 DR. HEITHAUS: What it can do is help us
53:49 recreate a three-dimensional track of the hammerhead.
53:53 And it samples at such a fast rate.
53:55 We can see if they're doing burst swims
53:57 to try to catch something.
53:59 And you're out here in Boca Grande,
54:00 we know that bull sharks and hammerheads
54:02 can be on a collision course.
54:04 So learning more about each
54:05 is really important to understand
54:07 how they're going after a prey
54:09 or are they maybe eating one another?
54:12 NARRATOR: By the time the last line is in the water,
54:15 it's time to circle back and check the first
54:18 where something is already on.
54:24 DR. HEITHAUS: So, this is a blacktip shark
54:26 and they're one of the more common species
54:28 along the coast of Florida.
54:30 And these are snacks for great hammerheads.
54:34 NARRATOR: Catching the hammerhead's prey is a good sign for the mission.
54:39 MORRIS: Here goes. Okay. Oh, there it goes.
54:41 DR. HEITHAUS (off screen): And away.
54:44 NARRATOR: The next hook looks more promising.
54:47 DR. HEITHAUS (off screen): Yeah, it's dragging it.
54:48 HAGAN: I saw the buoy actually made a splash.
54:51 DR. HEITHAUS: Yeah. This is not nurse shark,
54:54 not blacktip.
54:57 -Yes! Hammerhead! -HAGAN (off screen): Whoo!
54:58 -DR. HEITHAUS: Whoo! -HAGAN: That's a biggun.
55:01 DR. HEITHAUS: Two of 'em. There's another one right here.
55:03 -HAGAN: What? -DR. HEITHAUS (off screen): We got two hammerheads.
55:07 NARRATOR: The second hammer is free swimming,
55:09 analyzing the situation.
55:12 Hammerheads are known to eat their own
55:14 when the opportunity arises.
55:17 HAGAN (off screen): We might have a predation
55:18 about to happen.
55:21 NARRATOR: They need to secure the hooked shark
55:23 as quickly as possible.
55:26 But there's another problem.
55:28 HAGAN: I tried to pull on that, but there's no give.
55:33 DR. HEITHAUS: We've got a hammerhead here
55:34 wrapped up in a crab pot.
55:37 NARRATOR: Until they untangle it,
55:39 the hammerhead is a sitting duck.
55:42 And the second hammerhead circles
55:45 closer and closer.
55:48 DR. HEITHAUS: Okay. You gotta go to the right.
55:50 -You gotta get reverse. -HAGAN (off screen): Port side?
55:53 MORRIS (off screen): We gotta get him away from that other shark.
55:55 DR. HEITHAUS: I know.
55:59 Ahh! Look out! Look out! Look out! Look out!
56:03 MORRIS (off screen): How about we swing it out?
56:07 NARRATOR: The team struggles to untangle the line
56:10 before the great hammerhead becomes shark bait.
56:17 DR. HEITHAUS: (grunts) Forward.
56:21 Let go. Let go. Let go.
56:24 -Yes, free! -HAGAN (off screen): Oh.
56:26 -DR. HEITHAUS: Nice job. -HAGAN: Yeah. (laughs)
56:28 DR. HEITHAUS: Okay, we just have the shark now.
56:31 -HAGAN: Holy cow. -DR. HEITHAUS: That is a big animal.
56:35 Well, we got a really nice 10-foot-plus great hammerhead.
56:38 We have another slightly smaller one around.
56:40 This is the exact size we want for this tag.
56:44 Oh, beautiful.
56:48 I don't see the other one now.
56:49 HAGAN (off screen): We probably spooked the other one off.
56:52 NARRATOR: But the battle to subdue the shark is only beginning.
56:56 MORRIS: You know, the hairs on your skin
56:57 start to stand up a little bit.
56:58 Once you get what you want, you wanna keep it.
57:00 DR. HEITHAUS (off screen): Look out. Look out. Look out.
57:02 -Don't try this at home, kids. -MORRIS: Nicely done.
57:04 HAGAN (off screen): Definitely female.
57:09 Hello, gorgeous.
57:14 NARRATOR: Val attempts to secure the shark's powerful tail.
57:18 -DR. HEITHAUS: Get it? -HAGAN (off screen): No.
57:19 I couldn't get that lower lobe.
57:21 It was close.
57:23 NARRATOR: Handling a shark this big is proving difficult
57:26 without the help of their teammate Erin.
57:29 -(Hagan grunts) -DR. HEITHAUS: We're gonna move the top lobe.
57:31 (grunts)
57:33 We're gonna lose this shark.
57:35 -HAGAN (off screen): Okay. -(grunts sharply)
57:37 NARRATOR: The urgency is compounded by the fact
57:39 that great hammerheads are fragile.
57:42 MORRIS: There's theories that they fight an awful lot
57:45 when they're on a hook and they overexert themselves
57:47 and they run out of energy very quickly.
57:49 HAGAN: It's wearing us out. It's wearing her out.
57:51 And we want this animal to survive.
57:58 DR. HEITHAUS: Hey, slow it, slow it.
58:00 NARRATOR: The shark zooms around
58:02 to the other side of the boat, trying to throw the hook.
58:06 DR. HEITHAUS: Jack, can you come back?
58:07 MORRIS: Yeah. Okay, what do you want me to do?
58:09 DR. HEITHAUS: I want you to get the dorsal.
58:11 Let's clamp this thing on and get it.
58:13 Otherwise we are gonna lose this animal. -MORRIS: Alright.
58:16 NARRATOR: Finally, the tail rope is secured.
58:18 HAGAN: Come on.
58:20 DR. HEITHAUS: Put the tag on.
58:23 Get it as far as you can.
58:25 Excellent.
58:26 HAGAN: I was very focused on the tail
58:28 and then I looked up and I saw that the tag was on.
58:34 DR. HEITHAUS: Good. Let's get a quick measurement and go.
58:36 Fast, fast, fast, fast.
58:39 HAGAN (off screen): 345.
58:40 DR. HEITHAUS: The hook is bent and out.
58:42 You gotta get that tail rope up fast.
58:47 -Good swim. -HAGAN: Whoo!
58:50 NARRATOR: The biologging tag will capture 3D data,
58:53 providing valuable insight
58:55 into how great hammerheads move through the water.
58:59 And help the team see how these giants
59:01 stack up against bull sharks.
59:08 With the tag finally recovered and a clean bill of health,
59:11 Erin's back on board to walk Mike
59:13 through the hammerhead data.
59:15 DR. HEITHAUS (off screen): She can build a computer model
59:17 so we can see not just how it navigates and where it went,
59:21 but maybe how it's attacking its prey.
59:25 SPENCER: This is when the hammerhead is released.
59:27 We start at the surface and then just go straight down.
59:30 And then we can actually see
59:32 how the animal starts to move around.
59:36 NARRATOR: The shark heads down to a depth of about 40 feet.
59:40 It swims away from the boat in sweeping lateral movements.
59:45 SPENCER: Here, we see that the shark
59:48 is kind of meandering down a little bit slower
59:51 and is kinda midrange,
59:52 and then there's a really quick turnaround.
59:55 NARRATOR: It cuts through the water with its hydrodynamic head,
59:59 making several tight, very rapid turns.
60:02 SPENCER: And then there's a really quick
60:04 bolt up to the surface,
60:07 almost a vertical line.
60:09 DR. HEITHAUS: There's probably a reason for that
60:11 because why else would you burn that energy
60:12 -if you didn't have to? -SPENCER: Yeah.
60:14 We can say, okay, using the mathematical models,
60:17 actually how many calories would a shark need
60:19 to consume to sustain that sort of movement pattern?
60:22 DR. HEITHAUS: If you need a lot of energy,
60:23 you gotta eat that bigger prey
60:25 to get you more energy like other sharks.
60:29 NARRATOR: Erin's tags were only beginning
60:30 to reveal the secret abilities of the great hammerhead.
60:37 When it tilts its head, the hydrodynamic potential
60:40 of the great hammerhead cephalofoil is unleashed,
60:44 allowing the shark to move and turn with rapid precision.
60:48 And this makes hammerheads more nimble and agile
60:51 than other sharks,
60:52 including bulls.
60:55 DR. HEITHAUS: If you combine the speed,
60:58 the size, and maneuverability,
61:00 I mean, that's an impressive predator.
61:04 Bull shark versus hammerhead, who wins?
61:07 SPENCER: I vote hammerhead.
61:08 DR. HEITHAUS: One for team hammerhead.
61:12 NARRATOR: The awesome power
61:13 of the great hammerhead is coming into focus.
61:17 But Mike and the team are no closer to understanding
61:19 why the hammerhead was attacked
61:21 by bull sharks at Boca Grande.
61:26 NARRATOR: The team has proven that great hammerheads
61:29 are formidable opponents,
61:31 but what about the other contender in the battle?
61:34 DR. HEITHAUS: Now it's time to investigate
61:35 the other species in this matchup.
61:37 Bull sharks.
61:40 NARRATOR: Maxing out at around ten feet,
61:42 the bull shark is smaller than the great hammerhead.
61:46 But what it lacks in size, it makes up for it elsewhere.
61:50 It's thick with a broad head and big mouth,
61:54 built for taking out large prey.
61:57 The bull shark is super adaptable.
62:00 It has a reputation for being aggressive.
62:03 DR. HEITHAUS: Seeing that video
62:04 really shows us that bull sharks
62:06 might attack great hammerheads and kill 'em.
62:11 But the question is, is this a common event
62:13 that's happening more often
62:15 when they're out there coming into contact?
62:19 NARRATOR: To dig deeper into the bull shark component of this matchup,
62:22 Mike enlists Dr. Yannis Papastamatiou.
62:26 DR. HEITHAUS: Yannis is one of the top shark scientists in the world,
62:28 and has helped developed new technologies
62:31 to get more insights into their behavior.
62:36 For this project, we're gonna try something
62:39 that's never been done before.
62:42 We wanna put a camera on the back of a bull shark.
62:44 And until now, that's only been done with sharks
62:46 that have been caught,
62:48 and that might really change the behavior of the shark,
62:50 so we're gonna go out there and try to put a camera
62:53 on a bull shark without catching it.
62:58 NARRATOR: Along the southeast coast of Florida,
63:00 there's a thin band of warm, shallow water.
63:04 It creates a shark super highway,
63:07 bringing all sorts of species in contact with one another,
63:12 including lots of bull sharks.
63:15 DR. PAPASTAMATIOU: I'm really hopeful
63:17 we'll get this tag on,
63:18 but I, you know, I'm also a little bit nervous
63:20 because it's going to be somewhat challenging
63:22 to get a tag on a free-swimming bull shark
63:25 in blue water, in a current.
63:27 I'm hopeful.
63:29 But it's going to require a well-behaved shark.
63:32 And I also hope she won't bite me.
63:35 DR. HEITHAUS: We're heading about four miles offshore,
63:37 and that's where we should be able to find bull sharks.
63:42 DR. PAPASTAMATIOU: We should get about ten hours of video footage.
63:45 DR. HEITHAUS: Then that dissolves in a couple days,
63:46 -there's nothing left on it. -DR. PAPASTAMATIOU: Yep, yep.
63:47 So within a week, there'll be nothing
63:49 on the shark's fin at all.
63:52 NARRATOR: To keep the shark at arm's length,
63:54 they'll use a spring-loaded pole
63:55 to snap the tag on the shark's fin.
64:00 -DR. PAPASTAMATIOU: Okay, so that's now primed. -DR. HEITHAUS: Right.
64:02 DR. PAPASTAMATIOU: If you now click the small trigger...
64:04 -DR. HEITHAUS (off screen): Watch your fingers. -DR. PAPASTAMATIOU: Yep.
64:06 DR. HEITHAUS: One, two, three.
64:07 -DR. PAPASTAMATIOU: And that'll pop. -DR. HEITHAUS: Yeah.
64:09 DR. PAPASTAMATIOU: We just need one to behave the right way
64:12 and we'll get it on.
64:14 DR. HEITHAUS: If we pull this off,
64:15 it'll be a world first.
64:17 DR. PAPASTAMATIOU: No pressure. (laughs)
64:19 DR. HEITHAUS (off screen): No one's ever done it.
64:20 There's no pressure. Just go do it.
64:23 NARRATOR: If bull sharks are hunting hammerheads
64:25 more commonly than thought,
64:27 this camera could pick up hard evidence.
64:44 To bring a bull shark in and keep it close enough
64:47 for a tag deployment, bait is needed.
64:51 It injects a constant scent trail into the current,
64:54 drawing a roadmap directly to the divers.
65:05 DR. PAPASTAMATIOU:
65:09 NARRATOR: It's a silky shark.
65:13 She makes tight circles, sniffing out the food
65:16 and sizing up the human competition.
65:20 Silky sharks are a bold species
65:22 that spend a lot of time in the open ocean,
65:25 where food is scarce.
65:32 The bait is working...
65:35 but it's not the species they're after.
65:40 DR. HEITHAUS: Silky sharks don't really have
65:41 a sense of personal space,
65:43 especially if you have a camera in your hand.
65:49 NARRATOR: Then as quickly as they came,
65:51 the silkies disappear.
66:01 DR. PAPASTAMATIOU:
66:07 NARRATOR: The bull shark zeroes in on the bait.
66:14 It's a big female.
66:21 In order to tag a free-swimming bull,
66:23 they'll need the most bold and inquisitive shark they can find.
66:29 Experts generally agree
66:31 that bulls are one of the most dangerous shark species.
66:35 Most bull shark-human interactions
66:37 take place in murky water,
66:39 where biting is the only way to identify possible prey.
66:43 In clear open water, the team and the bull shark
66:47 can see one another
66:48 and maintain healthy boundaries.
66:52 She's a good candidate for the camera tag.
66:55 DR. HEITHAUS: We got the bull sharks we wanted.
66:57 If this goes well, the shark's gonna swim away
66:59 with the camera on it, and we will be done.
67:01 NARRATOR: With daylight fading,
67:03 the team has limited time to pull this off.
67:08 It's a deployment that's never been done before.
67:15 The big female comes in closer.
67:18 She's curious.
67:23 Confident.
67:27 The perfect shark.
67:29 Yannis readies the trigger.
67:31 He needs to slip the opening of the clamp
67:34 over the dorsal fin of the shark.
67:38 It's a game of inches.
67:40 One miss and the shark will be spooked.
67:46 NARRATOR: Clamping the tag on a free-swimming bull shark
67:49 is a cat-and-mouse game.
67:55 Every time he gets close, the bull changes direction.
68:11 DR. PAPASTAMATIOU:
68:16 NARRATOR: Success.
68:19 DR. HEITHAUS:
68:23 NARRATOR: In a first for science,
68:25 the bull shark swims off, unfazed by its new bling.
68:36 DR. PAPASTAMATIOU: So the tag is on an animal.
68:38 First part is done.
68:40 She's the perfect size,
68:41 she came in close and took my shot, and, uh, it worked.
68:45 In the end, she responded perfectly,
68:47 didn't seem to bother her much at all,
68:48 she just slowly swam off.
68:50 DR. HEITHAUS: Camera on. Everybody's okay.
68:53 -DR. PAPASTAMATIOU: Yeah. -DR. HEITHAUS: Now, one more step.
68:54 -Get the camera back. -DR. PAPASTAMATIOU: Getting the camera back.
68:57 NARRATOR: The tag will remain on the shark
68:59 for two days.
69:01 Tracking one bull will allow the team
69:03 to see everything from the shark's point of view.
69:07 But camera tags only tell one part of the story.
69:11 To see if hammerheads are on the bull shark menu
69:13 like in the video,
69:15 the team has to take a cloacal swab,
69:18 otherwise known as a fecal sample.
69:20 DR. HEITHAUS: One of the most important things
69:22 we need to know about predators is what they eat.
69:24 Usually, that's been figured out
69:26 by looking at the stomachs of dead sharks.
69:30 DR. HEITHAUS: It turns out, if you just get a little swab
69:33 and collect shark poop,
69:35 you can run that through a DNA test
69:37 and see what had been in its stomach.
69:40 This cloacal swabs are gonna help us figure out
69:42 if these bull sharks are eating a lot of other sharks
69:46 and may even go after great hammerheads.
69:50 NARRATOR: The next morning,
69:51 Mike and PhD student Davon Strickland
69:54 head off shore to swab bull sharks.
69:57 Davon is part of the next generation of marine biologists
70:01 trying to unravel the mystery
70:03 of how sharks interact with one another.
70:05 DR. HEITHAUS: He also happens to be a co-captain
70:08 of FIU's football team.
70:10 DAVON STRICKLAND: With football being a game of inches,
70:12 how that's translated in the shark work
70:14 is you gotta make sure you know your role,
70:16 because there's so many things that could go wrong,
70:18 you gotta be able to work as a team.
70:22 DR. HEITHAUS: He also is a pretty good person
70:23 to have on the boat when we're handling big sharks.
70:25 We need those long arms.
70:26 (indistinct chatter)
70:32 Oh, my gosh. The visibility here is insane.
70:37 NARRATOR: They set their lines just at the edge of deep water.
70:41 DR. HEITHAUS: So we are right where we'd expect
70:43 to find bull sharks,
70:44 the perfect depth range,
70:46 so that's why we're just gonna drift along here with the bait.
70:52 I thought I saw a shadow there.
70:56 Oh, there's a shark right there.
70:58 NARRATOR: It's an eight- to nine-foot bull shark.
71:01 STRICKLAND: Let me take it, let me take it.
71:02 -DR. HEITHAUS: Yeah. -STRICKLAND: Oh, there's two of 'em.
71:04 DR. HEITHAUS (off screen): Okay, that should help.
71:06 NARRATOR: The larger shark makes the first move.
71:09 DR. HEITHAUS: There, it's right, it's right next to the bait,
71:11 it's taking a look at it.
71:13 Take it, take it, take it.
71:14 Oh, oh, oh. Yup. It took it. Okay, get ready.
71:17 Watch your feet.
71:18 Okay, I think we're in business.
71:28 Careful, careful.
71:32 Yup, slow, slow.
71:34 Heads up, heads up. Clear, clear, clear.
71:38 Move, move, move, move, move.
71:42 That is a big bull shark.
71:44 Neutral.
71:48 Heads up now. Oh!
71:50 DR. PAPASTAMATIOU: He go?
71:51 DR. HEITHAUS: Bit the line.
71:54 STRICKLAND: So close, but yet so far.
71:56 DR. HEITHAUS: Bummer.
71:58 DR. PAPASTAMATIOU: The shark actually bit through the mono.
72:00 She was fresh, so she was really strong.
72:03 So we got out to the surface,
72:04 but she had the mono in her mouth.
72:06 That tooth just sliced through it.
72:09 It's the way it goes.
72:12 NARRATOR: It's not long before they have another curious shark.
72:15 DR. PAPASTAMATIOU (off screen): Shark.
72:19 NARRATOR: A big female.
72:22 DR. HEITHAUS: Back up, back up, back up!
72:25 Oh, damn!
72:38 DR. PAPASTAMATIOU (off screen): Okay. Pull the line.
72:41 DR. HEITHAUS: Nice. Yes.
72:43 Okay. Whoo!
72:46 Good job.
72:47 NARRATOR: The team makes sure she is calm
72:49 and getting water through her gills.
72:51 DR. HEITHAUS: This is perfect.
72:54 NARRATOR: Then they take a measurement.
72:56 -DR. PAPASTAMATIOU: 187. -DR. HEITHAUS: Yup.
72:58 It probably outweighs you by a hundred pounds.
73:00 STRICKLAND (off screen): Oh.
73:01 And this fish is longer than I am tall.
73:07 -DR. HEITHAUS: Okay. -DR. PAPASTAMATIOU: Alright.
73:08 DR. HEITHAUS: So what we need to do is get her upside down,
73:10 we're gonna do this cloacal swab,
73:11 we need to try to keep it out of the water.
73:15 NARRATOR: Flipping the shark on its back
73:16 puts it into tonic immobility,
73:19 a relaxed, trance-like state.
73:22 It helps keep everyone safe during workups.
73:26 They'll send the swab off to be analyzed
73:28 for hammerhead DNA.
73:31 While they have the shark, they will also implant
73:33 a permanent tracking transmitter in her belly.
73:36 DR. HEITHAUS: Right there?
73:37 DR. PAPASTAMATIOU: Yeah, that's fine.
73:38 NARRATOR: The shark will now alert the team
73:40 any time it passes a receiver
73:41 in a network along the coast of Florida and beyond.
73:45 DR. HEITHAUS: We can follow them for years,
73:48 so using the transmitters, video cameras,
73:51 and the DNA techniques, we can start to piece together
73:54 a much better picture of bull shark life in general.
74:00 NARRATOR: The acoustic tags can help
74:01 the team see where and when bull sharks may overlap
74:05 with great hammerhead habitat.
74:08 It could also reveal whether bull sharks
74:10 are gathering in groups.
74:15 DR. HEITHAUS: Okay, it's in.
74:16 NARRATOR: All that's left is to suture the wound
74:18 and release the shark.
74:25 Everything's in place.
74:31 STRICKLAND: Let me know when you're ready.
74:32 DR. PAPASTAMATIOU: Okay.
74:33 STRICKLAND: It's out. Nice!
74:41 NARRATOR: The team is confident.
74:42 If these bulls are hunting hammerheads,
74:44 evidence will be with them soon.
74:50 Two days later, the bull shark's fin cam surfaces.
74:54 DR. PAPASTAMATIOU: It did pop off about six miles offshore.
74:56 but then we had a pretty strong current,
74:58 so it was very rapidly moving offshore.
75:01 NARRATOR: When they finally catch up to it,
75:03 it's in deep water,
75:04 way out in the Gulf Stream.
75:07 DR. PAPASTAMATIOU: I was really, really happy
75:08 when that tag was in my hands.
75:14 NARRATOR: Back at the lab,
75:15 the team discovers the tag captured hours of video.
75:21 DR. PAPASTAMATIOU: This is the first time that one of these camera tags
75:23 is being put on a free-swimming bull shark,
75:25 and so I'm really excited to see
75:27 what the tag is going to show.
75:30 NARRATOR: The shark swims away as if nothing happened.
75:33 It's proof their tagging technique
75:35 is minimally stressful to the animal.
75:38 It cruises alone for hours.
75:42 -Then... -DR. HEITHAUS (off screen): Whoa.
75:44 DR. PAPASTAMATIOU (off screen): So, there's another shark came right over it.
75:47 -DR. HEITHAUS: Yeah. -DR. PAPASTAMATIOU: There's another one.
75:48 That's one, two, three, four,
75:50 five, six, seven.
75:52 NARRATOR: It's a gang of bull sharks.
75:54 DR. HEITHAUS: Yeah, look at that.
75:55 DR. PAPASTAMATIOU: I mean, that's right on top of each other.
75:58 There's a lot of sharks here.
75:59 DR. HEITHAUS (off screen): One there.
76:01 -DR. PAPASTAMATIOU: There's another one there. -DR. HEITHAUS: Look at that.
76:03 DR. PAPASTAMATIOU (off screen): It's just bull sharks all over the place.
76:05 And we're seeing at least
76:07 six, seven, eight individuals in frame.
76:10 -Camera's only pointing forward. -DR. HEITHAUS: Yeah.
76:12 DR. PAPASTAMATIOU: It tells nothing about
76:13 on the sides or behind.
76:15 DR. PAPASTAMATIOU (off screen): So whatever number we calculate,
76:17 the group size will be larger.
76:19 DR. HEITHAUS: And these are big animals.
76:22 DR. PAPASTAMATIOU: I have no idea what is going on here.
76:24 I mean, a lot of this is just not known.
76:25 You know, why are all these sharks
76:26 hanging out in these regions?
76:29 NARRATOR: The footage didn't show
76:31 any interactions with great hammerheads,
76:33 but it has confirmed a remarkable social life
76:36 between bull sharks.
76:39 DR. HEITHAUS: Are they feeding in groups?
76:41 Maybe these bull sharks are actually
76:43 maintaining relationships with other sharks
76:45 or working together when they're hunting.
76:49 NARRATOR: And the results from the cloacal swabs also arrived.
76:52 DR. HEITHAUS: It turns out that these bull sharks
76:55 were eating other sharks.
76:57 We didn't get any great hammerheads,
76:59 but it does show that these bull sharks
77:01 are eating big prey
77:02 and it's plausible
77:04 that they could go after other larger sharks.
77:07 NARRATOR: Scientists already know that sharks are hesitant
77:09 to take on the risk of a one-on-one fight with an equal.
77:14 It's possible the video evidence points
77:16 towards something scientists haven't considered before,
77:19 multiple sharks using their collective strength
77:22 to take down another apex predator.
77:25 In order to see whether this dynamic exists
77:28 between multiple bulls and hammerheads,
77:31 Mike jumps into the ring himself.
77:36 The Bahamian islands of Bimini
77:38 are only 50 miles east of Florida.
77:42 But worlds away in terms of shark activity.
77:47 Bulls regularly patrol these waters
77:51 and great hammerheads visit in the winter.
77:54 It's a prime location to observe them up close.
77:59 DR. HEITHAUS: That water is crystal clear
78:00 and so you can actually get in the water
78:02 with the great hammerheads in a way
78:04 that you couldn't in Boca Grande.
78:08 It's also an area where both of them are coming into
78:11 at least some semblance of proximity,
78:14 but are they actually battling it out?
78:17 Or do they give each other space?
78:21 NARRATOR: It's the ideal spot to witness
78:23 these two predators coming head-to-head.
78:31 Local scientist Candace Fields
78:33 will lead this leg of the expedition.
78:35 CANDACE FIELDS: I'm from Nassau, Bahamas,
78:37 so Bimini is an absolutely amazing place
78:40 for great hammerhead sharks,
78:41 mainly because of the fact that there's so much prey available for these guys.
78:47 NARRATOR: Candace brings Mike to a dive site
78:49 known for hammerhead aggregations.
78:52 But the occasional bull shows up here, too.
78:56 When they arrive,
78:57 a swarm of nurse sharks is already on patrol.
79:01 DR. HEITHAUS: We're really interested to see
79:02 if, like, one bull shark comes in
79:05 or if maybe a group shows up
79:07 because it sure is seeming like
79:09 -bull sharks may not be as solitary as we used to think. -FIELDS: Mm-hmm.
79:12 Hopefully we'll see both hammerheads
79:13 and maybe bull sharks.
79:15 And so I'm just super pumped to get in the water
79:16 and just see what we got.
79:19 NARRATOR: They don't have to wait long.
79:21 -DR. HEITHAUS: Got one? -FIELDS (off screen): Yeah.
79:22 DR. HEITHAUS: Oh. Oh, yup. Hammer.
79:24 Time to get geared up.
79:36 NARRATOR: The team drops to the bottom
79:38 and camps out next to the chum crate.
79:43 It's not long before the great hammerhead
79:45 comes in to investigate.
79:50 It's a nine-foot male.
79:55 His body posture is relaxed as he circles closer.
80:02 They watch the great hammerhead
80:04 make sharp, agile turns.
80:10 Just like what Erin is seeing in her data.
80:16 Then a second hammerhead enters,
80:19 a female, about the same size as the male.
80:23 She's no threat to the other shark.
80:27 They're solitary individuals here investigating the bait.
80:34 DR. HEITHAUS: Candace and I could see
80:35 that maneuverability they have,
80:37 you know, how they're able to move up and down,
80:39 and also how they interact with one another.
80:44 NARRATOR: Both hammerheads look strong and healthy.
80:48 DR. HEITHAUS: It's really awe-inspiring to be
80:50 so close to such big animals.
80:57 NARRATOR: Then shadows appear from the surface.
81:01 Bull sharks.
81:04 They glide in to survey the scene below.
81:08 Three of them.
81:11 A potential gang.
81:13 DR. HEITHAUS: Here's our opportunity to see
81:15 how these sharks interact when they get together.
81:18 NARRATOR: The bulls descend,
81:20 swimming a wide, careful arc around the two hammerheads.
81:25 They size each other up,
81:27 pushing in closer.
81:32 The bulls are smaller
81:34 but they have numbers.
81:36 A challenge over bait could happen at any second.
81:41 Then they move in to investigate the humans.
81:50 DR. HEITHAUS: They seem to be a little less focused
81:52 on what's going on,
81:54 kind of out front of us and more,
81:55 "How do I get close when you don't see me?"
82:00 NARRATOR: The hammerheads are dominant,
82:02 showing no sign of fear.
82:04 The body language of the bulls is relaxed and confident.
82:09 It's a bull versus hammerhead standoff.
82:12 Suddenly, a game-changer appears on the horizon.
82:19 DR. HEITHAUS:
82:27 NARRATOR: The new hammerhead on the scene
82:29 dwarfs the other sharks.
82:34 It's a 13-foot female.
82:38 Now, it's a three-on-three showdown
82:40 between bull sharks and hammerheads.
82:45 The imposing shark works her way
82:47 to the center of the group.
82:56 DR. HEITHAUS:
82:59 NARRATOR: She's about the same size
83:00 as the hammerhead attacked in Boca Grande Pass.
83:03 MAN (off screen): That's insane.
83:05 NARRATOR: But this super predator
83:07 brings a completely different power dynamic to the face-off.
83:11 FIELDS: It felt as though she was running the show.
83:17 She was making much closer passes to us
83:19 than the other sharks were,
83:21 perhaps because she feels far less threatened by us
83:24 as potential predators.
83:27 NARRATOR: The bull sharks circle, sizing her up.
83:34 The hammerhead makes quick turns,
83:36 possibly bracing for a three-on-one fight.
83:40 DR. HEITHAUS:
83:46 NARRATOR: The bull sharks take turns coming in...
83:50 closer and closer.
83:54 The 13-foot great hammerhead stands her ground.
84:08 The bull flinches first.
84:14 As the hammerhead approaches,
84:16 the bull gets a sense of her true size...
84:21 and retreats.
84:25 FIELDS: Things underwater kind of changed.
84:28 The dynamic changed a bit.
84:30 So it was really cool to see that she kind of
84:33 made everybody else clear out a little bit.
84:44 NARRATOR: The team has now seen first-hand the power and dominance
84:47 a giant great hammerhead has over bull sharks.
84:58 DR. HEITHAUS: Bull shark kinda gave way first.
85:00 They both turned,
85:01 but it's like that bull shark was kinda,
85:03 "You can have the swim lane first."
85:05 FIELDS: Exactly. Unlike most people think
85:06 that all sharks are at the top of the food chain,
85:08 but that's obviously not the case, right?
85:09 DR. HEITHAUS: Yeah, you can really see
85:10 the difference in maneuverability.
85:12 Those bull sharks are, like,
85:13 a tank trying to get turned around
85:15 and the hammerheads just spin on a dime.
85:17 FIELDS: Absolutely.
85:19 I mean, maybe that's another reason
85:20 why the bulls aren't coming in as much.
85:22 You know, the hammerheads have so much body
85:24 and so much capacity to move around,
85:26 whereas the bulls don't.
85:29 DR. HEITHAUS: That's just what we were looking for,
85:31 an opportunity to see these two big predators together,
85:35 but it doesn't mean when they get together,
85:37 it's gonna be one eating the other.
85:39 It might actually take special situations
85:41 for bull sharks to go after hammerheads or vice versa.
85:45 NARRATOR: After bearing witness to the head-to-head showdown,
85:48 Mike believes there's an answer
85:50 to which shark would come out on top.
85:54 DR. HEITHAUS: Based on what we've seen,
85:55 I think if it actually came down to a battle
85:58 and you had a bull shark and a great hammerhead,
86:02 the great hammerhead's gonna come out on top.
86:04 They are bigger, they are fast, they are maneuverable.
86:08 NARRATOR: So how did the hammerhead
86:09 become a victim in Boca Grande?
86:14 Back in Florida, Mike sits down
86:16 with the video one more time.
86:20 Instead of focusing on the aggressive behavior
86:22 of the bull sharks,
86:24 he takes a closer look at the hammerhead.
86:27 DR. HEITHAUS: The thing that I noticed
86:28 is that the hammerhead's
86:29 not really swimming quite right.
86:33 Think about that 3D track from Erin,
86:35 those sharks are able to turn on a dime.
86:39 NARRATOR: Unlike the giant great hammerhead in Bimini,
86:41 when faced with a threat,
86:43 these sharks swim stiffly in a straight line.
86:47 DR. HEITHAUS: I would've expected it to be
86:49 accelerating rapidly, turning quickly,
86:51 or even turning the tables
86:52 'cause that hammerhead was bigger
86:55 than the biggest bull shark that's there.
86:57 That suggest to me that that was a hammerhead
86:59 that was in trouble.
87:04 NARRATOR: The great hammerhead
87:05 may have been injured before the attack.
87:10 It was the height of tarpon season.
87:13 It's possible the hammerhead was hit by a boat
87:16 or accidentally hooked on a fishing line
87:19 while pursuing a tarpon.
87:21 It's likely the bulls sensed that it was compromised
87:25 and went in for the attack.
87:26 DR. HEITHAUS: And the bull sharks were then able to just follow it
87:29 and wait for the hammerhead
87:30 to be too exhausted or injured to fight back.
87:34 And then they finished it off.
87:38 This video is amazing,
87:40 but probably the exception to the rule.
87:43 In the end, bull sharks and great hammerheads
87:46 are both amazing top predators in their own right,
87:50 but when it comes to
87:51 bull shark versus great hammerhead,
87:53 they probably don't go after one another
87:55 unless the scales are really unbalanced.
87:58 But if a great hammerhead or a bull shark's in trouble,
88:01 they can become dinner.
88:08 NARRATOR: Two apex predators dominate the ocean--
88:13 the great white shark,
88:15 a lone hunter,
88:18 and the orca, known as the killer whale.
88:29 Both sit atop the oceanic food chain,
88:32 so when orca begin to hunt
88:34 great white sharks in South Africa,
88:38 it's big news.
88:41 Experts want to know, will it happen again?
88:44 And if so, where?
89:00 It's happened before.
89:02 Orca have hunted and killed great white sharks,
89:06 one of the first reported cases
89:08 off the coast of California in 1997,
89:12 and again in 2017 off South Africa,
89:16 five dead white sharks washed ashore.
89:20 Shark scientists wondered why orca would hunt
89:23 dangerous prey like a white shark.
89:26 With attacks happening in oceans around the world,
89:28 experts are looking for similarities and patterns
89:32 and what the effect would be on the marine ecosystem,
89:38 particularly in New Zealand.
89:41 KINA SCOLLAY: When the orca started to kill
89:43 the great white sharks in South Africa,
89:45 the rest of the sharks actually disappeared
89:47 and haven't come back for years.
89:50 If that happened in New Zealand,
89:52 not only would we lose this population of great whites
89:55 that we've learned so much about,
89:58 but it would also be disastrous for this ecosystem
90:01 to lose an apex predator like that.
90:05 NARRATOR: There are several theories
90:06 about exactly why the sharks vanished,
90:10 but the coincidence of the orca attacks
90:12 and the disappearance of the sharks is hard to ignore.
90:17 And there's a lot at stake,
90:19 including the health of the marine ecosystem.
90:22 (calling)
90:25 New Zealand has a local orca population
90:28 of between 150 and 200,
90:32 while the white shark aggregation
90:34 is one of the largest in the world,
90:38 estimated to be over 5,000.
90:43 If the orca begin to go after white sharks here,
90:47 they have plenty to choose from.
90:53 New Zealanders Kina Scollay
90:55 and Dr. Ingrid Visser are investigating.
90:59 Orca could be hunting great white sharks already,
91:02 but no white sharks have washed up on New Zealand beaches...
91:10 ...so they're searching for other signs of orca predation--
91:15 any strange behavior,
91:18 wounds from an encounter,
91:21 anything that points to orca hunting white sharks.
91:37 NARRATOR: Local great whites are in New Zealand waters
91:39 from December to June,
91:41 when many will leave on their annual 2,000-mile migration
91:45 to the coast of Australia and the Tropical Pacific.
91:50 Local orca, on the other hand,
91:53 remain in New Zealand waters all year round,
91:56 roaming the coastline in search of prey.
92:00 (bang)
92:01 Ingrid is New Zealand's top orca specialist,
92:05 but today is her first dive with great white sharks.
93:04 NARRATOR: Great white sharks in this area
93:06 are curious and aggressive, which makes them dangerous.
93:13 Orca and white sharks have shared
93:15 the top of the ocean food chain for millions of years,
93:19 so why would orca attack great whites like these now?
93:24 INGRID: Even though orca are the largest
93:26 of the dolphin family and they can be friendly,
93:28 we still have to consider that they are
93:30 one of the top predators of the ocean.
93:35 NARRATOR: Ingrid's research tracks the 200 or so orca
93:38 living in New Zealand's waters.
93:41 INGRID: Yeah, I know, big guy! Hang in there.
93:43 The exciting thing about this adventure for me
93:45 is that we've got two top predators,
93:48 and we don't really know what's happening between them.
93:57 NARRATOR: Orca and white sharks
93:58 are the top two ocean predators,
94:01 yet they're fundamentally different.
94:06 Orca are air-breathing mammals.
94:09 (blows air)
94:11 White sharks are water-breathing fish.
94:15 Orcas live in pods of up to 40,
94:18 made up of individual family units
94:20 that remain together for life and hunt cooperatively.
94:25 Some new research suggests
94:28 white sharks may occasionally hunt in groups,
94:32 but they tend to hunt alone.
94:38 The largest great white ever recorded measured over 20 feet
94:43 and weighed 5,000 pounds--
94:46 small for an orca.
94:48 Killer whales can grow to 30 feet or more
94:52 and weigh as much as 20,000 pounds.
94:59 But as different as they are,
95:01 orca and great whites are both sophisticated,
95:04 tough, and hungry predators.
95:14 NARRATOR: Kina and Ingrid dive again and again,
95:18 searching for evidence.
96:34 NARRATOR: In 2017,
96:36 a predator-on-predator interaction of another kind
96:40 took place along the coast of South Africa.
96:43 Five dead great white sharks washed up on local beaches.
96:49 The news is shocking.
96:52 Scientists conducted an investigation.
96:55 Of all the evidence collected,
96:57 it was the bite marks on the shark bodies
97:00 that revealed the killers.
97:02 The teeth marks belonged to orca.
97:09 Stranger still,
97:11 the killer whales had taken only the shark livers
97:14 and left the rest of the bodies untouched.
97:19 This was the first recorded case
97:21 of orcas killing white sharks in South Africa.
97:24 Shark and orca scientists
97:26 wondered when and where it might happen again.
97:30 INGRID: We can't rule out that the orca here in New Zealand
97:33 could hunt great white sharks in exactly the same way.
97:39 (bird squawking)
97:43 NARRATOR: The Foveaux Strait
97:45 sits at the southern end of New Zealand,
97:48 over 6,000 miles to the east of South Africa.
97:54 Both regions have large populations of great whites
97:58 and roaming pods of orca,
98:01 a combination that resulted in a fatal confrontation
98:04 in South Africa.
98:06 And if white sharks and orca
98:08 ever cross paths in New Zealand,
98:11 this is where it could happen, in the Foveaux Strait.
98:44 NARRATOR: Large, boisterous,
98:46 and aggressive great white sharks.
98:51 What possible motive could an orca have
98:53 for attacking a great white?
98:57 There isn't a clear answer,
98:59 but to Ingrid, it makes some sense.
99:04 INGRID: Typically, in New Zealand,
99:05 the orca are not just targeting prey to take the whole thing.
99:09 They're focused on particular parts of them,
99:13 and that's the liver.
99:16 NARRATOR: When the South African orcas
99:17 killed the great whites, this is what they did--
99:22 hunting for liver with great precision.
99:32 Liver is a prize for any predator.
99:36 To hunt, mate,
99:39 and migrate thousands of miles
99:42 takes energy.
99:47 Liver is pure fuel,
99:50 so when they hunt, they're filling the tank.
99:58 New Zealand orca feed on the 25 species of rays and skates
100:03 that swim in local waters.
100:06 The preference for rays is unique to orca in New Zealand.
100:12 But recently, local orca have acquired a taste
100:16 for shark liver
100:18 from a smaller cousin of the great white, the sevengill.
100:29 And evidence suggests South African orca
100:33 started on sevengill sharks...
100:38 (calling)
100:39 ...and graduated to great whites.
100:48 NARRATOR: Ingrid Visser and Kina Scollay are looking
100:51 for evidence that orca are hunting great white sharks
100:55 in New Zealand waters.
100:57 Ingrid has evidence that there's a disturbing pattern
101:01 in orca hunting.
101:03 New Zealand orca are hunting sevengill sharks,
101:07 just like the South African orca.
101:12 Sevengill sharks grow to 9 feet long and 200 pounds,
101:17 a much larger meal for an orca than a small ray.
101:21 But the sevengill shark is no easy prey.
101:26 INGRID: Sevengills are relatively new on the orca menu,
101:29 but I've seen it a few times now.
101:32 You see the orca, and they're very, very precise
101:35 in how they do it.
101:36 And I've got footage of orca with the sevengills
101:38 where they've ripped the pectoral fin
101:40 right under the pectoral girdle there,
101:42 and they've extracted the liver.
101:46 WOMAN: Whoopee! Oh, there's a shark.
101:48 Oh, shark! Shark!
101:50 INGRID: One of the things I find fascinating
101:52 is how the sevengills will actually turn
101:54 and defend themselves against the orca.
102:01 The way the orca hunt the sevengills is pretty impressive.
102:05 First of all, they'll come in,
102:06 and they'll karate chop the shark,
102:08 so they'll just come and lift their tail up
102:09 and whack them on the back.
102:17 Then they grab the sharks by the pectoral fin
102:19 and rip them open and pull the livers out.
102:23 NARRATOR: Ingrid captured rare footage
102:25 of orcas hunting sevengills in northern New Zealand.
102:49 Their precision in hunting for shark liver is clear.
103:02 KINA: What's really fascinating is that in South Africa,
103:04 the orca started by hunting sevengills,
103:08 and then they moved on to the great white sharks.
103:11 So, knowing what's gone on in South Africa,
103:14 what concerns me is exactly the same thing could happen here.
103:21 NARRATOR: A concentration of sevengill sharks
103:24 lives up along the western coast of New Zealand.
103:28 Kina has dived with them for years,
103:30 knows just where they live and how they behave.
103:34 KINA: Beautiful.
103:36 NARRATOR: They decide to drop in and see if the sevengills
103:39 can give them any clues.
103:46 Fiordland National Park is a vast, remote wilderness
103:50 on the western shore of New Zealand's South Island.
103:53 Most areas are accessible only by helicopter or boat.
103:58 KINA: You know, really, you fly over these mountains,
104:00 and you're in a completely different world,
104:04 and then under the water, it's completely different again,
104:06 different to just about anywhere else you'll dive.
104:09 Amazing.
104:12 NARRATOR: These deep fiords are murky,
104:14 stained with tannins from the ancient forest.
104:17 It makes the water dark, even in the middle of the day.
104:25 If orcas came here to hunt sevengills,
104:29 it's possible no one would ever know.
104:33 KINA: I actually haven't been in here for about two years.
104:36 So, that's after diving here
104:38 month in, month out for many years,
104:41 and I really felt like I knew these sevengills so well.
104:44 All this talk about orca eating them,
104:47 I just kind of want to come and have a look.
104:50 INGRID: Yeah. Absolutely, Kina, and I mean, look,
104:52 that ties in with the sightings that we've had recently
104:54 of the orca coming down this bit of coastline,
104:57 so I'd be fascinated to know if they're coming up here
104:59 to your sevengills.
105:04 NARRATOR: The only place for Kina and Ingrid to land
105:07 is on a small fishing trawler in the middle of nowhere.
105:16 KINA: My little secret spot
105:17 is only just literally one minute's flying time from here,
105:21 so I think it's easiest if I gear up here.
105:24 INGRID: Yeah.
105:25 KINA: And then I'm gonna hop in the helicopter
105:27 and just buzz around there and bomb in!
105:45 NARRATOR: Diving without a cage,
105:47 Kina will have to be careful of the sevengills
105:50 and keep an eye out for orca.
105:54 They could be anywhere.
105:59 NARRATOR: Kina Scollay is paying a visit
106:01 to an aggregation of sevengill sharks
106:04 in Fiordland National Park, New Zealand...
106:13 ...and knows just where to find them.
106:20 He's looking for any signs
106:22 that orca are hunting these sevengill sharks.
107:21 NARRATOR: The sevengills are here,
107:24 drifting in and out of sight...
107:32 ...checking out the intruder.
108:13 Ooh!
108:47 NARRATOR: Sevengills may be prey for orca,
108:50 but these sharks are no pushovers.
109:12 Oh!
109:26 That was awesome to go and visit those guys.
109:29 INGRID: Yeah, great jump!
109:30 KINA: Yeah, cheers, mate.
109:31 That splash and the noise of the helicopter
109:34 really has to attract them,
109:36 and they were straight on top of me when I got in,
109:40 but not as many as I would have expected to see.
109:43 INGRID: Really? Okay, well, that's really interesting
109:45 because given that we know historically
109:47 that orca are coming in here,
109:48 and we've had the reports recently,
109:50 and now you're seeing less sharks in here, too,
109:52 so, you know, it's indicative
109:54 that something's been going on, right?
110:00 NARRATOR: Lower sevengill numbers
110:02 could mean a few things are going on,
110:04 including predation by larger predators,
110:09 like orcas.
110:12 That would mark a change in their usual diet.
110:18 Traditionally, New Zealand orca hunt the many species
110:22 of rays and skates that live in these waters.
110:28 Like all dolphins, they have a special ability to find them.
110:33 INGRID: Orca hunt using echolocation,
110:35 which is a series of clicks that they send out...
110:37 (clicking)
110:39 ...that bounce back and give them incredible information.
110:41 (calling)
110:43 They can tell even if a shark has a full tummy.
110:47 NARRATOR: It works like sonar.
110:50 The orca can detect their prey
110:52 even when it's buried in the sand.
110:55 (calling)
110:58 But filling up on rays and skates can be hard work
111:02 and burn a lot of precious energy.
111:06 (calling)
111:09 INGRID: Do you see them?
111:11 Look, they're in a really tight group over here, right there.
111:15 NARRATOR: Many rays are bottom feeders
111:18 and spend much of their time on or buried
111:20 in the sandy ocean floor.
111:25 Orca jaws are not designed to grab them off the bottom,
111:30 so the orca work together,
111:33 chasing the rays upward and catching them in the open.
111:43 But ray hunts don't always go smoothly.
111:48 Rays often flee to shallower water...
111:59 ...making it dangerous for the orca.
112:07 There is the risk of a fatal stranding as the tide goes out.
112:22 And the ray may still escape.
112:30 NARRATOR: When orca hunt rays in New Zealand,
112:33 their size is not always an advantage.
112:48 After a lot of work
112:50 and coordinated effort among several orca...
112:56 ...they catch the ray,
113:00 but it's a tiny payoff for all that effort.
113:07 And compared with white sharks, rays are a snack.
113:13 One 700-pound great white shark liver could be equivalent
113:16 to nearly 175 ray livers,
113:21 and it's a lot more work to hunt multiple rays.
113:26 While it is more dangerous to hunt a single great white,
113:30 it might be worth the risk.
113:39 KINA: It's really hard not to think
113:41 when you see animals that big
113:43 that their liver must be gold to a liver-eating orca.
113:48 NARRATOR: A great white liver can grow to 25 percent
113:52 of the shark's total weight.
113:54 If a 12-foot great white weighs 1,000 pounds,
113:58 it may have a liver weighing 250 pounds,
114:03 a big payoff for the orca.
114:16 Kina and Ingrid are off one of the Foveaux Strait's
114:19 large colonies of seals.
114:27 Over the summer, the white sharks consume many.
114:30 (barking)
114:33 Their livers are swollen with seal blubber and oil.
114:38 Ingrid and Kina are looking at the length of the sharks
114:42 to estimate their liver weight.
115:19 NARRATOR: Great white sharks as prey for anything,
115:22 even orca, is hard to fathom.
115:26 But the orca may see them that way.
115:29 INGRID: All our evidence points to the fact
115:31 that the New Zealand orca have a very strong culture
115:33 of hunting sharks.
115:38 If the rays were removed from the food web
115:40 here in New Zealand,
115:43 chances are the orca would shift their food preferences,
115:49 and they could start targeting great white sharks in earnest.
115:54 NARRATOR: So far, the supply of rays and skates
115:57 has been ample, but add warming oceans
116:01 to natural fluctuations in all animal populations,
116:05 and it's hard to predict what will happen.
117:26 NARRATOR: The half dozen white sharks swimming by
117:29 are more than impressive.
117:32 To an orca, they may represent
117:34 the food value of 1,000 rays.
117:55 NARRATOR: At 16 feet, this one great white shark alone
117:59 is the equivalent of 200 rays to a hungry orca.
118:03 It might be a motive for predation.
118:19 KINA: It's hard not to think
118:20 an animal as intelligent as the orca,
118:21 that they're coming through here at the perfect time of year,
118:25 when the livers are fat,
118:27 they've gotta see this as a food source.
118:28 And even though it's high risk,
118:30 we've seen in South Africa that they can decide it's worth it.
118:34 There's such a food source there.
118:35 INGRID: Oh, absolutely.
118:37 KINA: You've gotta wonder
118:38 whether they're not already onto this.
118:39 It may have been going on for a long time in New Zealand,
118:42 but we've just never heard about it.
118:43 INGRID: Yeah, exactly.
118:50 NARRATOR: Ingrid and Kina have found many similarities
118:53 between New Zealand and South Africa.
118:59 (calling)
119:00 In both places, the orca already have a taste
119:04 for sevengill sharks.
119:10 But after the orca killed five great whites in South Africa,
119:14 all the other white sharks disappeared.
119:18 In New Zealand, all of these sharks
119:22 are still here and hunting.
119:34 Then, like a bolt from the blue,
119:37 Kina and Ingrid finally see what they've been looking for.
119:53 NARRATOR: Kina and Ingrid are observing
119:55 local white shark behavior
119:58 when a male with a wound catches their eye.
120:44 NARRATOR: An unusual mark on a white shark's dorsal fin
120:48 looks like a bite.
121:24 KINA: What were those rake marks on the fin?
121:25 That was fascinating.
121:27 They were quite wide apart and very straight,
121:29 which was interesting.
121:31 And those were uniform. That was something new to me.
121:34 INGRID: Yeah, and it looks very similar
121:35 to what I see in the stingrays
121:37 when the orca have been biting them.
121:39 You know, you get these sort of like someone's raked the garden,
121:42 but it's teeth rake marks,
121:44 and that's what it looked like to me.
121:50 Yeah, so let me show you these.
121:52 This is a picture of a orca's teeth.
121:57 See how the teeth curve backwards?
122:00 And so here, this is a close-up of these teeth marks,
122:02 and this is what I think we saw on that great white shark.
122:06 KINA: Yeah, amazing.
122:10 INGRID: And when you look at the scale on here.
122:12 KINA: Same thing, that was what we saw on that shark!
122:14 INGRID: Yeah, so if I had to put money on it,
122:16 I'd say that it was orca.
122:18 KINA: Well, I certainly can't think of anything else,
122:19 and that is pretty phenomenal.
122:21 This could well be the evidence we're looking for.
122:24 NARRATOR: The bite marks could be a breakthrough,
122:26 the first visible sign
122:28 of orca-on-white-shark predation they've seen.
122:37 Ingrid and Kina devise an experiment
122:39 that will use sound instead of sight.
122:42 INGRID: Orca use a range of different sounds.
122:44 They use clicks for echolocation.
122:46 (clicking)
122:47 They use whistles and pulsed calls
122:49 when they're communicating.
122:51 (calling)
122:52 It's really impressive.
122:54 NARRATOR: So they'll use recorded whale sounds
122:57 and observe how the sharks react.
123:02 KINA: It's a little-known fact about great white sharks
123:05 that they actually have amazing hearing.
123:08 So, I think if the great white sharks react to orca sounds,
123:13 that might mean that they've met them before.
123:16 How they react could possibly even tell us
123:19 whether that experience was hunting or otherwise,
123:23 so this experiment is going to be very interesting.
123:29 NARRATOR: They mount an underwater speaker
123:31 on the dive cage.
123:32 The plan--play sounds from several other kinds
123:35 of whales first to try and draw the sharks in.
123:39 INGRID: Oh, that's perfect.
123:40 NARRATOR: Once white sharks are around the cage,
123:43 Ingrid will play the sounds of New Zealand orcas hunting.
123:47 KINA: Done.
123:48 It will be interesting to see if they are actually scared of orca
123:52 or if they, you know, if they know what it's like
123:54 to be scared of something.
124:12 INGRID: Do you copy me, Kina?
124:20 INGRID: Well, look, I'm gonna start playing
124:22 the first set of sounds now.
124:23 This is the humpback whale calls that you recorded.
124:32 (humpback whale singing)
124:35 NARRATOR: This is humpback whale song...
124:39 (singing)
124:42 ...and possibly a great white dinner bell.
124:46 White sharks are known to hunt whale calves
124:49 in the Tropical Pacific.
125:02 (humpback whale singing)
125:16 NARRATOR: The circling great whites
125:18 begin to rush the speaker and the cage.
125:46 (humpback whale singing)
126:22 NARRATOR: The sharks are clearly responding
126:24 to the humpback whale sounds.
126:26 The question is, how will they react
126:29 to the sound of New Zealand killer whales?
126:37 NARRATOR: Ingrid Visser and Kina Scollay
126:39 want to see how great whites react
126:42 to the sounds of hunting orca.
126:44 (humpback whale singing)
126:46 First, as a test, they play humpback whale song.
126:49 (humpback whale singing)
126:53 The sharks come straight to the sound...
127:01 NARRATOR: ...including the shark
127:03 with the bite marks on its dorsal fin.
127:10 They have to wait a few minutes
127:12 for the sharks to settle down after the humpback reaction.
127:19 INGRID: Now I'm just gonna play you the sounds
127:20 from the orca that eat the salmon.
127:22 I recorded these guys off North America.
127:25 Stand by.
127:29 (orca whistling)
127:38 Can you hear that?
127:42 (orca squeaking)
128:01 (orca whistling)
128:10 INGRID: Yeah. Well, I guess that doesn't really surprise me,
128:12 given that these are the fish-eating orca.
128:15 NARRATOR: The sharks appear unresponsive
128:17 to the North American orca calls,
128:20 but these sounds have never been heard before
128:23 in New Zealand.
128:25 INGRID: Yeah. Kina, so now I'm gonna play you
128:27 the New Zealand orca.
128:29 These are probably the ones
128:30 that the great whites have heard before.
128:34 Stand by.
128:38 (orca calling)
129:08 NARRATOR: The sharks' response
129:09 was clearly to move away from the sound.
129:12 (orca calling)
129:45 NARRATOR: Ingrid and Kina observe that the sharks
129:47 keep the source of the orca sounds in sight
129:51 but stay well out of the way.
130:13 INGRID: How was that, mate?
130:14 KINA: Yeah. Well, another awesome dive down here,
130:16 but interesting.
130:17 We've only really had a glimpse, eh?
130:20 NARRATOR: The orca sounds changed the behavior
130:23 of the white sharks,
130:24 from fearlessly coming into the sounds of the humpbacks
130:29 to moving off and keeping their distance
130:31 when they heard hunting orca.
130:36 But was this a typical animal reaction to danger?
130:41 INGRID: You know, when you think about the bite marks
130:43 that we saw that could have been the orca,
130:45 and you saw the way that the great white sharks,
130:48 you know, there was a bit of reaction there, but not full-on.
130:51 KINA: Obviously, we'd have to do this a lot of times
130:53 to be able to say for sure,
130:55 but maybe actually the sharks aren't so scared of orca.
130:59 INGRID: Well, maybe New Zealand sharks are more exposed to it,
131:02 like even from when they're little sharks,
131:04 and so they just become habituated to it.
131:07 NARRATOR: When orca killed five white sharks
131:09 in South Africa in 2017,
131:12 many scientists believed it was a first for the region.
131:16 But is it possible that white sharks
131:18 have been fending off orca attacks
131:21 for thousands of years
131:23 and what we see are only the most recent incidents
131:26 in an ancient and ongoing battle?
131:31 INGRID: I guess the big thing for me is, you know,
131:33 how far are these orca going?
131:35 And we've got some evidence that suggests that they're
131:38 at least trying to have a nibble on them, but, uh, you know,
131:41 I'm curious to know just how far they've taken it.
131:46 NARRATOR: So far, there have been
131:48 no reported serial shark attacks in New Zealand.
131:53 But here on the far side of the world,
131:56 the unseen struggle between orca and white shark goes on,
132:02 in secret, for now.
132:08 NARRATOR: Sharks, dolphins,
132:10 an epic war waged beneath the waves.
132:13 MAN: He's got a dolphin in his mouth!
132:15 NARRATOR: Brain against brawn.
132:17 MAN: Oi, they're fighting, they're fighting. Oh, (bleep)!
132:19 WOMAN: Dolphins are very capable predators
132:21 in their own right.
132:22 MAN: People forget that killer whales
132:24 are actually dolphins.
132:26 MAN: I've never ever seen anything like this before.
132:28 NARRATOR: Now for the first time,
132:30 a chance to see how these gangs of the deep go to war.
132:34 Can there be a truce?
132:36 Or are these top predators locked in a blood battle?
132:43 Off Australia, predators stalk their prey.
132:48 These are called false killer whales,
132:51 but they're actually dolphins,
132:53 just super-sized.
132:55 They grow up to 20 feet long
132:58 and travel in pods of 10 or more.
133:03 Today they're on the hunt for shark.
133:08 The pod gives chase.
133:12 The shark can't outswim them.
133:15 The dolphins work as a team,
133:18 box in the shark,
133:20 and move in for the kill.
133:25 FRANCES FARABAUGH: Dolphins are very capable predators
133:27 in their own right.
133:29 NARRATOR: Frances Farabaugh is a shark biologist
133:31 at Florida International University.
133:34 FRANCES: I feel like there's this conception
133:35 in the general public that dolphins are the heroes
133:38 and sharks are the antagonists or the villains.
133:41 NARRATOR: When it comes to the fierce relationship
133:44 between dolphins and sharks, there's a lot we get wrong
133:48 and a lot more that we don't even know.
133:51 FRANCES: Both of these organisms are predators
133:53 that are making smart, intelligent decisions
133:56 about how to survive and how to feed.
133:59 NARRATOR: Primal decisions that often bring
134:01 these two top predators into conflict.
134:05 In some areas, 30% of the dolphin population
134:09 bear the marks of shark encounters.
134:12 And that's on the dolphins that survived.
134:15 But even smaller dolphins aren't defenseless.
134:18 They wield a powerful arsenal of weapons to combat sharks.
134:22 FRANCES: It's a mistake to think of dolphins versus sharks
134:25 as some kind of mismatched pairing.
134:28 There are advantages and disadvantages,
134:30 but they're quite evenly matched.
134:32 NARRATOR: Frances is on an expedition to gain insight
134:35 into the battle between sharks and dolphins.
134:40 She teams up with research specialist Kirk Gastrich
134:44 on the far side of the world
134:45 in what might be the bloodiest front
134:47 in the shark-dolphin war:
134:50 a place called Shark Bay.
134:54 KIRK GASTRICH: In Shark Bay, we know that
134:55 there are these interactions between sharks and dolphins.
134:58 The amount of dolphins with shark-inflicted wounds
135:01 on them is really, really high here.
135:04 FRANCES: We know that around 75% of dolphins here
135:07 show scars from interactions with sharks.
135:11 NARRATOR: On the western tip of Australia,
135:13 Shark Bay is a sprawling natural preserve.
135:17 3.2 million acres of pristine marine habitat,
135:20 overflowing with fish and squid.
135:23 A dolphin paradise.
135:25 Only one problem.
135:27 KIRK: They call it Shark Bay
135:28 because this place is just loaded with sharks.
135:32 NARRATOR: Frances and Kirk have a lot of ground to cover.
135:35 Their floating laboratory for the next week
135:37 is the 120-foot ship Infamis.
135:40 ASH: Straight in here, guys. Welcome aboard.
135:43 FRANCES: Thank you.
135:44 NARRATOR: Rounding out the expedition team
135:46 are Ash Sutton, the ship's captain...
135:48 ASH SUTTON: If you've come looking for sharks,
135:49 this is the hot spot around here.
135:51 NARRATOR: ...and Duncan Brake, an underwater cinematographer
135:54 who's been filming both sharks and dolphins for 20 years.
135:58 DUNCAN BRAKE: Dolphins seem to have
136:00 a bit of this love/hate relationship with sharks.
136:02 I don't know, but there definitely seems to be
136:05 this dichotomous relationship between the two species.
136:10 NARRATOR: The mission on the expedition:
136:12 capture video evidence of shark/dolphin combat.
136:16 They hope to detail how sharks outsmart
136:19 one of the most intelligent animals on Earth,
136:22 and find out how dolphins evade
136:24 one of nature's most efficient killers.
136:27 To get the footage, the team has custom-built cameras
136:31 to attach to shark fins.
136:33 KIRK: We know that there are interactions,
136:35 but we haven't really seen them with our own eyes.
136:40 NARRATOR: Do the sharks hunt during the day or night?
136:43 Do they target the sick or injured?
136:45 All questions the fin cam can help answer.
136:52 About 5,000 dolphins call these waters home despite the sharks.
136:58 They've figured out not just how to survive
137:01 but how to thrive.
137:02 FRANCES: There are lots of strategies and advantages
137:05 that dolphins have when they're trying to defend themselves.
137:08 One of them is that they're very social animals.
137:12 We know that, through research, they tend to hang out
137:15 in larger groups when they feel they're more vulnerable,
137:17 like at night and when they're resting.
137:19 NARRATOR: They also live and work together in pods,
137:22 a cooperative that not only provides protection
137:25 but is an effective means to hunt prey.
137:28 FRANCES: They're very fast, they're very strong,
137:31 and they easily outmaneuver a shark.
137:32 So, it's important not to think of them
137:34 as some kind of David versus Goliath.
137:37 Dolphins are powerful, incredible predators.
137:41 NARRATOR: Sharks don't play well with others.
137:45 There are no shark pods.
137:47 They're solitary hunters.
137:49 And in this part of the world,
137:51 the number one threat to dolphins is the tiger shark.
137:55 FRANCES: From a dolphin's perspective,
137:56 a tiger shark is always a danger,
137:58 because it only takes one slip-up
138:00 for you to be consumed by a shark.
138:03 NARRATOR: Tiger sharks have earned themselves
138:04 a nasty reputation.
138:06 DUNCAN: As an underwater cameraman,
138:07 you can be literally be covered in other shark species,
138:10 but then that big, old tiger shark will roll into town,
138:14 and you are looking at that one big tiger.
138:17 NARRATOR: Named for their distinctive stripes,
138:19 these apex predators can top 14 feet.
138:23 And they have an outsized appetite to match.
138:27 Unlike white sharks, which use their immense power and speed
138:31 to take down seals and dolphins,
138:33 tigers are all about a casual kill.
138:36 DUNCAN: I think tiger sharks
138:37 are gonna sneak up on something and grab it
138:40 instead of actually having to chase it around
138:41 all over the ocean.
138:43 NARRATOR: Video footage of tiger sharks fighting dolphins
138:46 is extremely rare and extremely hard to capture.
138:50 But if the team can get it,
138:52 the footage could unlock the secrets of this unseen war.
138:58 The first step is to find the sharks.
139:02 The team uses a baited remote underwater video, or BRUV.
139:06 FRANCES: With BRUVs, I drop a frame with a camera
139:10 and some bait down to the bottom of the ocean.
139:12 I pull that back up, and then I watch the video through
139:14 to see what showed up.
139:23 Make sure that that bait arm is pointing down current,
139:25 and just make sure it's...
139:27 NARRATOR: Strong currents can easily topple the BRUV,
139:30 so Duncan will check it out on the bottom.
140:02 NARRATOR: Sharks can easily detect prey
140:04 through clouds of muck.
140:07 FRANCES: Sharks sort of have a sixth sense.
140:08 They can sort of electrorecept.
140:10 So they have these little organs towards the front of their noses
140:14 that are called ampullae of Lorenzini.
140:16 They kind of detect little electrical currents.
140:18 And so they're not relying
140:19 necessarily exclusively on sight to hunt.
140:30 NARRATOR: Remoras are fish that cling to sharks.
140:32 They swim alongside and feed on the host's scraps.
140:36 FRANCES: Large remora, maybe a large shark nearby.
140:48 NARRATOR: A large remora could mean
140:50 that a very large shark is closing in.
140:55 FRANCES: I didn't read that. Can you say again?
140:58 Duncan, Duncan, test, test, can you hear me?
141:08 FRANCES: Excellent.
141:09 NARRATOR: The BRUV is rolling.
141:11 They'll leave it for a day
141:13 and then find out if they're in the right spot for sharks.
141:16 DUNCAN: With this visibility,
141:17 it's probably time to get out of the water
141:19 and let the BRUV do its work, I think.
141:22 NARRATOR: Stories abound of sharks sneaking up on swimmers,
141:26 and dolphins zooming to the rescue.
141:30 In 2018, off the coast of Australia,
141:34 a snorkeler diving with a pod of dolphins
141:37 suddenly spots a Galapagos shark.
141:41 These large predators are known
141:43 to take down seals and sea lions.
141:47 Before long, more sharks appear,
141:52 and they're getting closer.
141:55 But he hardly believes what happens next.
141:58 (dolphins squeaking)
142:01 A pair of dolphins charge
142:04 and scatter the threatening sharks.
142:06 (squeaking)
142:09 A dolphin pod has safety in numbers.
142:12 When the matchup is one-on-one, it's usually a different story.
142:18 MAN: He's got a dolphin in his mouth!
142:21 NARRATOR: Recently, two Australian oystermen
142:23 capture this savage struggle up close.
142:28 JASON DARKE: I've never, ever seen anything like this before.
142:31 Only on TV, and even then, it's rare.
142:33 We were going about eight kilometers out.
142:35 We were probably halfway there
142:37 when off in the distance we noticed a fin
142:41 which we assumed straightaway would be a dolphin.
142:44 A dolphin. It's a dolphin.
142:45 Jai, here, hold my phone.
142:47 JAI DARKE: And once we realized the size of it,
142:49 there's no curve in the back of it,
142:52 we realized that it was not a dolphin.
142:55 JASON: This was much bigger than a dolphin fin,
142:58 much, much bigger.
143:05 JASON: The shark we knew straightaway
143:07 was a great white shark.
143:09 It would've been approximately 10 to 12 foot.
143:11 Rather large.
143:13 He's coming this way, he's coming this way.
143:16 He's coming right to us.
143:18 He's got a dolphin in his mouth!
143:21 He just swam straight past us with a dolphin in his mouth.
143:24 JAI: This is (bleep) you see on Nat Geo Wild.
143:26 NARRATOR: But then things get wilder.
143:30 JASON: So, we'd been watching the shark for a while,
143:32 and I was carefully following the shark
143:34 as it was swimming away with the dolphin,
143:36 when, all of a sudden, out of nowhere...
143:39 Oh, my god, another one, another one!
143:40 JAI: Oi, oi, oi! Oh, (bleep)! Oh, (bleep)!
143:46 JASON: Oh, my god, another one, another one!
143:47 JAI: Oi, oi! Oh, (bleep)! Oh, (bleep)!
143:50 JASON: He's got a dolphin in his mouth!
143:52 NARRATOR: Sharks and dolphins.
143:54 This vicious rivalry has been raging for millions of years.
143:59 Two Australian oystermen get a firsthand look
144:02 at the aftermath of a battle.
144:04 JASON: Oh, my god, another one, another one!
144:06 JAI: Oi, oi, massive one, massive one!
144:08 Oh, (bleep)! Oh, (bleep)!
144:11 Look at it!
144:12 Oh, that just come out from underneath the boat.
144:15 The moment I saw the second shark,
144:17 adrenaline started pumping through my veins.
144:20 I didn't know what just happened.
144:22 Oh!
144:24 That scared the (bleep) out of me!
144:26 JASON: The second shark was bigger than the first.
144:28 It would've been 12 to 14 foot, probably,
144:30 but it was definitely bigger.
144:32 JAI: It was huge.
144:34 Oi, they're fighting, they're fighting,
144:36 they're fighting, they're fighting!
144:37 Oh! Oh, (bleep)!
144:40 He just stole that dolphin!
144:42 He just stole the dolphin!
144:44 Oh, he's massive!
144:46 Oh!
144:48 JASON: Look at the size of the thing!
144:50 NARRATOR: A dolphin is worth fighting over.
144:52 FRANCES: We do know that if a shark gets the opportunity
144:55 to eat a dolphin, they absolutely will.
144:58 And in fact, it's a really prized food source.
145:01 Like many marine mammals, dolphins have all this blubber,
145:04 so that's a good nutritious meal.
145:07 NARRATOR: From the injuries, it's clear the dolphin
145:09 was initially attacked from behind and below.
145:13 JASON: He swam straight past us
145:14 with a dolphin in his mouth.
145:16 NARRATOR: How did the shark get past this dolphin's defenses?
145:19 FRANCES: Dolphins are really quite zippy.
145:22 They can outmaneuver a shark fairly easily,
145:24 especially if they're in deeper or open water spaces.
145:30 NARRATOR: To understand how sharks catch
145:32 these slippery creatures, the team heads to a beach
145:35 that offers a unique look at Shark Bay's dolphins.
145:40 FRANCES: So, we're right now at Monkey Mia in Shark Bay.
145:44 There has been 20 years
145:46 of really incredible ecological and biological research
145:49 on the interactions between sharks and dolphins.
145:51 NARRATOR: Dolphins were first drawn here in the 1960s
145:54 by fishermen sharing their catch.
145:57 Today the site is regulated by the Parks and Wildlife Service.
146:01 FRANCES: We have some friendly dolphins that come here
146:02 very regularly, and we get to see them up close and personal,
146:05 which is really special.
146:07 NARRATOR: No need for a baited underwater camera.
146:10 Here, dolphins come to you.
146:13 And they're covered in scars.
146:15 FRANCES: So this individual that's just approaching us
146:18 just now is called Piccolo.
146:20 And you can see on her dorsal and on her back,
146:22 she's got scars from encounters with sharks.
146:25 Dolphins make this trade-off.
146:27 A lot of the food that they want most
146:29 and the easy fishing grounds, the yummy fish,
146:31 occur around shallow seagrass beds.
146:33 Unfortunately, that's also where tiger sharks
146:36 preferentially like to hunt.
146:38 NARRATOR: To protect themselves,
146:39 dolphins have a secret weapon: echolocation.
146:43 They can send out a beam of sound
146:45 from a fatty part of their head, called the melon.
146:48 The sound beam bounces back and forms a mental image
146:51 in the dolphin's brain of the world around them.
146:54 FRANCES: Echolocation is the way that dolphins have to see
146:56 in dark and low-lit environments.
146:58 Basically, it's like radar or sonar.
147:01 NARRATOR: But there are limits to this superpower.
147:04 FRANCES: So, it works kind of like wide beams on a flashlight.
147:07 They can only see kind of directly ahead of them
147:09 or to the sides.
147:10 So, if they get attacked from the back or from underneath,
147:13 they probably won't see the predator coming.
147:15 NARRATOR: Dolphins have a blind spot,
147:17 and sharks know it.
147:21 NARRATOR: Great whites use their massive power
147:23 to charge from beneath in a breach attack.
147:28 KIRK: White sharks you would consider
147:29 more of an ambush predator.
147:31 FRANCES: It's probably the shark that you don't see
147:32 that you worry about,
147:34 because a lot of white sharks rely on surprise.
147:36 They're stealth predators.
147:39 NARRATOR: It's easy to sneak up on a lone dolphin,
147:42 but the safety of the pod can stop an ambush,
147:45 even from a great white.
147:48 A white shark swims with a group of dolphins.
147:53 The ocean-going mammals show no concern
147:56 for the killer in their midst.
147:59 Their ability to communicate and spot their stalker
148:02 gives the shark no chance at an attack.
148:07 The team heads out to search for more scarring,
148:10 and more signs of shark/dolphin battles.
148:14 FRANCES: To our port now just a little bit.
148:18 10, 11 o'clock.
148:19 Maybe 100 meters out.
148:24 KIRK: So, we've got one dolphin up here.
148:27 Appears just to be logging or just resting at the surface.
148:30 FRANCES: It definitely has scars.
148:33 KIRK: That's the thing about dolphins, though,
148:34 if they don't wanna stick around, they don't.
148:37 NARRATOR: It's a perfect display
148:39 of another dolphin defensive weapon: speed.
148:43 They can reach up to 22 miles per hour.
148:46 A simple flick of the tail and they leave a trail of bubbles,
148:50 able to outswim most predators, including sharks.
148:54 But there's a shark that's even faster.
148:57 The mako.
149:00 DUNCAN: Mako sharks are one of the fastest fish in the sea.
149:03 And compared to other sharks,
149:05 their speed and agility cannot compare.
149:08 NARRATOR: Mako sharks are torpedoes with teeth.
149:12 Blasting up to 45 miles per hour;
149:14 twice as fast as dolphins.
149:18 (woman screams)
149:19 WOMAN: Shark right here!
149:20 NARRATOR: Near Maui, Hawaii, Captain Steve Lawless
149:23 captures a mako and dolphin encounter off his snorkel boat.
149:28 (scream)
149:29 MAN: He's got the dolphin in his mouth.
149:30 NARRATOR: The mako has the dolphin by the tail;
149:33 a sure sign that the shark outswam its panicked prey.
149:37 MAN: Has he swallowed the dolphin
149:38 or is the dolphin hanging out of his mouth?
149:41 DUNCAN: I think a dolphin could quite easily
149:43 outmaneuver a tiger shark.
149:44 However, if we brought a mako shark to the table,
149:46 not a chance.
149:48 WOMAN: This is crazy!
149:49 NARRATOR: Luckily for the dolphins of Shark Bay,
149:51 there aren't many makos here.
149:54 But there are tigers, and the team wants to know
149:57 if they're in the right place to capture one.
150:01 Step one: retrieve the BRUV.
150:04 DUNCAN: How'd you guys do?
150:05 Everything back in one piece?
150:07 FRANCES: Everything's back in one piece.
150:08 DUNCAN: I can't wait to see what was down there with that remora.
150:12 NARRATOR: Is the footage binge-worthy?
150:19 Success: tigers on camera.
150:22 The team is in the right spot.
150:24 FRANCES: We know from BRUVs that this is an area
150:26 that has a lot of tiger sharks and many different habitats.
150:30 What we don't have evidence of on these BRUVs
150:33 is exactly what the sharks are eating.
150:35 NARRATOR: To really understand the shark/dolphin relationship,
150:38 Frances wants to capture a shark's-eye view of Shark Bay.
150:43 FRANCES: So, basically, what this is, is it's our fin camera.
150:45 What happens is we'll slot this over the fin of the tiger shark,
150:50 and we'll send it on its merry way.
150:52 KIRK: Alright, good to go? FRANCES: Good to go.
150:56 KIRK: Okay, got that?
150:57 NARRATOR: They set up a series of baited hooks
151:00 called a drumline.
151:01 FRANCES: Ready to go.
151:03 KIRK: Alright, going over.
151:05 Alright, we're on bottom.
151:09 FRANCES: One down.
151:10 KIRK: One down, four to go.
151:11 FRANCES: Alright, let's get the next one set.
151:14 NARRATOR: They check the lines every 30 minutes
151:17 to ensure no shark is harmed.
151:20 FRANCES: Got a shark on the line.
151:21 KIRK: Just want to see what we got.
151:23 Coming up!
151:24 Hooked good.
151:26 Coming under, coming under.
151:27 FRANCES: Alright, ready to go on that.
151:29 KIRK: Okay, on zero.
151:31 FRANCES: Zeroed.
151:33 Hold on.
151:35 KIRK: Watch it, Frances, watch it.
151:39 I'm losing the head here.
151:43 FRANCES: Oh!
151:46 NARRATOR: There's a primal conflict down in the deep:
151:49 dolphins and sharks.
151:52 MAN: Shark. WOMAN: Shark.
151:53 JAI: Oh, he's massive!
151:55 (scream)
151:56 JAI: They're fighting, they're fighting! Oh!
152:00 KIRK: Okay, on zero.
152:01 FRANCES: Zeroed.
152:06 KIRK: Watch it, Frances, watch it.
152:10 I'm losing the head here.
152:12 FRANCES: Oh!
152:14 NARRATOR: Shark researchers Frances Farabaugh,
152:17 Kirk Gastrich and cameraman Duncan Brake
152:20 are at one of the fiercest battlegrounds
152:22 in this ferocious struggle: Shark Bay, Australia.
152:27 FRANCES: Many of the dolphins that we've seen
152:28 have shown lots of evidence of encounters with sharks,
152:31 very specific scarring and bite marks.
152:34 So we know that these interactions are occurring.
152:37 NARRATOR: Their mission:
152:38 capture direct evidence of these battles
152:40 and observe offense and defense in action.
152:45 Which strategies work?
152:47 Which don't?
152:49 JASON: He's got a dolphin in his mouth!
152:51 NARRATOR: To do it, they want to catch
152:53 the region's supreme predator, the tiger shark,
152:57 and stick a camera on its fin.
152:59 KIRK: Pretty shark. Hooked good.
153:02 NARRATOR: They have their shark, but...
153:05 ASH: It's a bronzie.
153:07 DUNCAN: That moment when you're waiting for those stripes
153:09 to appear on the back of the shark,
153:11 and then you see a flash of bronze instead.
153:14 Yeah, it's almost heartbreaking.
153:16 You've got a shark; it's just not the right one.
153:19 NARRATOR: Bronze whalers are relatives of tiger sharks.
153:23 But they're not known for attacking dolphins.
153:26 KIRK: We'll get the bolt cutters ready, Frances.
153:28 FRANCES: Yep.
153:29 NARRATOR: The team decides to hang onto their fin cam
153:31 and keep searching for a tiger.
153:34 KIRK: Nice.
153:37 FRANCES: Okay, it's gone.
153:39 We just released it straightaway
153:41 and it was a really beautiful release.
153:43 DUNCAN: Right back to square one.
153:47 NARRATOR: Of nearly 500 species of sharks,
153:50 only about 10 target dolphins as prey.
153:54 The usual suspects top the list:
153:57 the tiger, great white...
153:59 JAI: Oh, he's massive! Oh!
154:02 NARRATOR: And hammerhead.
154:04 They mostly eat stingrays.
154:07 But a hammerhead will hunt down a dolphin given the chance.
154:12 MAN: Look at that shark, dude.
154:13 MAN: I got it, man. I got it all right here.
154:16 Holy (bleep).
154:18 NARRATOR: The notorious bull shark,
154:20 a known man-eater, makes the list.
154:23 DUNCAN: Bull sharks are very bold and brash.
154:25 Kind of bulldoze other sharks out of the way sometimes,
154:28 just to find out where the food is.
154:30 FRANCES: Every species of shark
154:31 is going to have different hunting modes,
154:34 different strategies, different sort of niches that they fill.
154:38 NARRATOR: But when it comes to hunting dolphins,
154:40 each of these different species share a common trait:
154:44 size matters.
154:46 JAI: Oi, oi, massive one!
154:47 JASON: Look at the size of the thing!
154:49 NARRATOR: To get past a dolphin's defenses,
154:51 the rule seems to be a shark needs to be as big or bigger.
154:56 But there are exceptions to every rule.
155:00 Off the Florida coast, a young blacktip shark is in pursuit
155:05 of a bottlenose dolphin more than twice his size.
155:10 DUNCAN: Yeah, blacktip sharks,
155:11 every time I've been in the water with them,
155:12 they always behave erratically.
155:15 They're like little kids on a sugar rush,
155:16 kind of bouncing around.
155:18 They don't really care about where you are.
155:22 They just want the cheeky free snack.
155:28 NARRATOR: The shark's running a risk.
155:31 His snack could attack.
155:37 The shark comes to his senses and backs off.
155:48 The team hopes to film their own dolphin and shark faceoff
155:51 with a fin cam.
155:53 FRANCES: Alright, one more.
155:55 KIRK: So we just finished checking the lines.
155:57 We re-baited everything.
155:58 We've got some fresh meat on there for the shark.
156:00 FRANCES: Ah, I think we actually got a shark on the line.
156:03 DUNCAN: As we were going around,
156:05 we noticed that both of the buoys were underwater.
156:08 KIRK: Watch your feet, watch your feet, watch your feet.
156:11 DUNCAN: So, like, for it to pull both those buoys down,
156:14 it was gonna be a huge animal.
156:15 KIRK: Alright, you can go neutral. Coming up!
156:17 DUNCAN: Yep, here he is coming up.
156:19 KIRK: Alright, hold on.
156:26 FRANCES: It's a tiger.
156:27 KIRK: Alright! Got a bruiser of a tiger.
156:30 DUNCAN: I jumped in the water.
156:32 The water around here is a little bit murky,
156:34 so we couldn't really tell how big she was
156:36 until we jumped in there.
156:40 KIRK: Ah, it's a big one. Big female.
156:46 FRANCES: Oh, it's huge.
156:48 DUNCAN: I've filmed tiger sharks all around the world.
156:50 However, jumping in the water here in Shark Bay
156:53 with these just huge, just off-the-chart,
156:56 ginormous, mama bus tiger sharks just blew my mind.
157:00 And it almost made some of the other sharks
157:02 that had been in the water look like tadpoles.
157:04 NARRATOR: Such a massive animal demands extreme caution.
157:08 FRANCES: Our first priority is the safety of everyone involved,
157:11 the safety of the animal, and then getting good science.
157:14 NARRATOR: Shark secured.
157:16 But there's a problem.
157:18 KIRK: Alright, this hook's straightening out,
157:20 so just be careful.
157:22 NARRATOR: A steel hook is the only thing keeping
157:25 this powerful shark safely in place.
157:28 And she's bending it.
157:31 KIRK: (bleep) It's straightening.
157:33 NARRATOR: If she straightens it much more,
157:36 this massive beast will break loose.
157:40 KIRK: Yeah, you are big, I know.
157:42 NARRATOR: Frances and Kirk have a decision to make.
157:45 KIRK: We can let her go, or we can try to do a workup,
157:48 hope this hook doesn't straighten fully
157:50 and we lose her before we get the camera on.
157:52 FRANCES: Alright, ready to go on that.
157:54 KIRK: Alright, Ash, you can come on over here.
157:57 NARRATOR: They decide to go for it.
157:58 KIRK: Come on up, Ash, we can probably get a tail on her now.
158:04 ASH: Got it.
158:06 We got a line on the tail, anyway.
158:08 KIRK: Yeah.
158:09 Once we lose control of the head though, we're (bleep).
158:11 NARRATOR: Keeping control of the shark's head is critical,
158:13 especially with her size.
158:16 A snap of the jaw could mean tragedy.
158:21 KIRK: Hands!
158:22 DUNCAN: This huge tiger shark, swinging around with its teeth.
158:25 Every time that shark shook its head,
158:27 the hook straightened a little bit more.
158:29 FRANCES: Okay, Kirk, incoming with the tape.
158:32 NARRATOR: The closest hospital is a six-hour boat ride away...
158:36 KIRK: Okay, hand me the tape again.
158:38 NARRATOR: ...more than enough time for someone to bleed out
158:40 if shark teeth meet human flesh.
158:43 KIRK: Okay, I'm zero, Frances, zero, zero, zero, zero.
158:45 FRANCES: Zero, I'm zeroed.
158:46 ASH: Okay, 3.8.
158:48 KIRK: 3.8.
158:49 NARRATOR: 3.8 meters.
158:51 This monster shark is 12 and a half feet long.
158:55 KIRK: She's so big.
158:58 NARRATOR: And the hook is straightening.
159:01 KIRK: Ah, it's probably gonna come out.
159:03 NARRATOR: If the shark breaks free,
159:05 it could swamp the boat...
159:08 KIRK: Yeah, she's pissed.
159:09 NARRATOR: ...or charge straight at Duncan.
159:12 KIRK: Maybe a little tighter on the tail, Ash.
159:13 ASH: It's gonna get lost!
159:14 KIRK: Watch out, watch out, watch out!
159:19 KIRK: Maybe a little tighter on the tail, Ash.
159:20 ASH: Yeah, it's gonna get lost.
159:21 KIRK: Watch out, watch out, watch out!
159:22 FRANCES: I got it, I got it.
159:24 NARRATOR: An almost 15-foot tiger shark
159:26 in Shark Bay, Australia, might be just perfect.
159:32 FRANCES: It's huge.
159:33 NARRATOR: The research team hopes to stick a fin camera
159:36 on the tiger's dorsal,
159:38 providing crucial insight into the epic clash
159:41 between sharks and dolphins.
159:43 But there's a problem.
159:46 KIRK: This hook's straightening out.
159:48 Watch your hands.
159:49 NARRATOR: The shark is bending the steel hook,
159:53 the only thing keeping her massive head still
159:57 and her bone-crushing jaws
159:58 away from underwater cameraman Duncan Brake.
160:02 DUNCAN: This tiger shark was on steroids, it was massive.
160:05 NARRATOR: Will the hook hold?
160:09 KIRK: If we're quick, we might be able to do this.
160:11 FRANCES: Got it.
160:11 NARRATOR: It's now or never.
160:13 KIRK: Alright, Frances, you ready?
160:14 FRANCES: Yep.
160:17 DUNCAN: That's pretty good,
160:18 that's going flush down the body.
160:20 FRANCES: Okay.
160:21 NARRATOR: The fin cam is on.
160:23 FRANCES: Clear.
160:23 KIRK: Okay. Awesome.
160:25 NARRATOR: They send her on her way.
160:28 KIRK: Dunc, I'm gonna do release, alright?
160:30 (snip)
160:34 DUNCAN: I really didn't comprehend
160:36 how big the animal was until it started swimming towards me.
160:40 Then she went right between my legs, and she was huge.
160:44 Then it swam off into the distance.
160:46 The fin cam looked like it was perfectly placed,
160:48 perfectly angled.
160:50 It's kinda creepy because within seconds,
160:52 in this water clarity, they just disappear.
160:57 KIRK: Cool.
160:58 FRANCES: Woo!
160:59 KIRK: We got it. Camera's out.
161:01 Now we're gonna check out, see what these guys
161:02 really do with their time.
161:04 FRANCES: That is a beautiful animal.
161:05 KIRK: Good work, Frances.
161:08 FRANCES: That was a truly massive individual
161:10 and just a beautiful, beautiful animal.
161:12 So I'm very excited to see what happens next.
161:15 KIRK: Any information we get back is gonna be novel.
161:17 So we're just really, really excited
161:18 to see what we get on this camera.
161:22 NARRATOR: Recently, another camera captured
161:24 a shark/dolphin clash, but this one flips the script.
161:28 DUNCAN: People forget that killer whales
161:30 are actually dolphins.
161:32 They're all part of the same family.
161:35 But they're bigger than tiger sharks,
161:38 and they're more cunning and more intelligent
161:39 than great whites.
161:43 If there's something that I am more cautious
161:45 of being in the water with than a shark,
161:47 it's definitely an orca, a killer whale.
161:52 NARRATOR: Off Costa Rica, a pod of orcas,
161:56 the world's largest dolphin, target a tiger shark.
162:05 DUNCAN: Orcas are so intelligent
162:06 that they will collaboratively hunt together
162:09 in order to take down their prey.
162:13 NARRATOR: The pod surrounds the tiger...
162:18 ...trapping it at the surface.
162:20 (orca sings)
162:23 One orca moves in,
162:27 locking the shark in its jaws.
162:31 Now the rest of the pod gets a piece.
162:36 DUNCAN: And what's more twisted
162:38 is that they won't even eat the whole shark.
162:40 They'll dissect it and take out a special little bit
162:43 that they like the taste of.
162:46 When you pitch an orca against a shark
162:49 or several orcas against one shark,
162:54 it's almost game over every time for the shark.
162:58 NARRATOR: This battle goes to the dolphins.
163:02 FRANCES: And just because bottlenose dolphins,
163:03 the ones that are here, are smaller
163:05 does not make them any less shrinking violets.
163:07 They're still very vicious predators.
163:12 NARRATOR: Back in Shark Bay...
163:14 KIRK: Is it getting stronger?
163:16 FRANCES: Nope.
163:17 NARRATOR: The team hopes for their own amazing footage.
163:23 After a day hitchhiking on the tiger shark,
163:26 the camera automatically detaches and floats free.
163:31 Now the team needs to track it down
163:34 in 3.2 million acres of open water.
163:39 FRANCES: I think we might've passed it,
163:41 'cause we're starting to get weaker
163:42 and the signal's coming from that way.
163:45 NARRATOR: They're fighting the elements
163:47 and the setting sun to find it.
163:50 KIRK: As long as we're going the right direction,
163:52 I'll keep looking.
163:53 FRANCES: Okay.
163:54 I don't know if you can see behind us,
163:56 we're getting out of Shark Bay and sort of into the ocean.
164:00 It's a race against the clock.
164:01 KIRK: Keep this heading for a little bit.
164:03 (beeping)
164:08 FRANCES: If we don't find it before sunset,
164:09 it's gonna be nigh on impossible to collect at night
164:13 just because then we're looking for a black thing
164:16 in a black ocean.
164:18 KIRK: I think we're getting really close.
164:19 It's getting pretty loud.
164:21 FRANCES: Yeah?
164:21 (beeping)
164:25 KIRK: Watch out, watch out, watch out!
164:26 If we're quick, we might be able to do this.
164:28 NARRATOR: After attaching a specialized fin cam
164:31 on a tiger shark...
164:33 KIRK: Alright, Frances, are you ready?
164:34 FRANCES: Yep.
164:35 Woo!
164:36 KIRK: Camera's out!
164:38 NARRATOR: A team of shark biologists needs to find it.
164:43 FRANCES: I think we might have passed it,
164:44 'cause we're starting to get weaker
164:46 and the signal's coming from that way.
164:49 NARRATOR: The camera floated free a few hours ago.
164:52 The hope is that it captured something never seen before:
164:55 a shark's-eye view of that shark
164:58 going fin-to-fin with a dolphin.
165:01 FRANCES: What we hope to find when we get that camera back
165:03 is we're really looking for how these organisms may interact
165:06 with their prey species, including dolphins.
165:08 NARRATOR: Documenting a dolphin encounter as a shark sees it
165:12 would be groundbreaking.
165:13 It could answer long-burning questions
165:16 about these two top predators.
165:19 It could also capture a whole lot of nothing.
165:24 FRANCES: The signal's definitely coming from this direction.
165:27 KIRK: Let me have a quick listen.
165:28 (beeping)
165:31 Got it right there! Right there.
165:33 FRANCES: For real? KIRK: Yup.
165:34 FRANCES: Oh, I see it! Yup! Ha ha!
165:38 Yes, Kirk. Well done.
165:40 That moment where we plucked the fin cam...
165:44 KIRK: Got it! Woo hoo!
165:46 FRANCES: ...from the sort of setting sun
165:47 and the seething ocean was incredible.
165:50 KIRK: Ha ha ha! There we go, guys.
165:52 Love it.
165:54 FRANCES: Now you have to make sure that it all worked.
165:58 Well, we have footage.
165:59 KIRK: That's a good start.
166:01 FRANCES: Let's find the release.
166:03 And boom.
166:04 KIRK: There she goes.
166:07 Kicking strong.
166:10 NARRATOR: Shark Bay, from the point of view
166:12 of a giant apex predator.
166:15 FRANCES: We did find it way out in that offshore there,
166:18 so maybe she gets deeper.
166:20 Although we might lose the light later on in the day.
166:23 NARRATOR: They've got hours of footage
166:24 of this tiger on the move.
166:27 It's valuable data;
166:29 just not the eye-popping action they hoped for.
166:33 FRANCES: This happens in fieldwork all the time.
166:34 But when you only have a limited window
166:37 and a couple shots or maybe one shot at it,
166:41 when that happens, it's rough.
166:44 Yeah, it doesn't, it doesn't feel great.
166:46 NARRATOR: Sometimes it's a matter of being
166:48 at the right place at the right time.
166:53 Captain Ash had recent luck of his own.
166:57 ASH: So we're just filming out here one day
166:58 and we saw this object.
167:00 See, that's a tiger at the back of the boat.
167:02 So we just followed it, four dolphins just appeared
167:05 out of nowhere with a juvenile dolphin, you'll see them here.
167:07 See? See, that's the tiger.
167:10 Little juvenile right in front of the shark.
167:12 We thought, "Gee, this tiger is just going to eat
167:14 this juvenile dolphin."
167:17 And watch what happens when the adults get involved.
167:21 They end up flicking this bit of seaweed
167:24 in front of the tiger shark
167:26 and distracting it from the little dolphin.
167:28 As if they're, like, teaching the little dolphin,
167:30 "Don't be scared of this tiger shark.
167:32 And just in case you get into trouble, there's that seaweed."
167:35 NARRATOR: The pod of dolphins work together
167:37 to keep the little calf safe from the tiger.
167:40 FRANCES: I mean, given the water clarity
167:42 and just also the sort of maneuverable space,
167:45 they probably felt this was a pretty low risk situation.
167:48 NARRATOR: Ash's footage points out a potential flaw
167:51 in the team's fin cam deployment.
167:54 The camera doesn't see any dolphins,
167:57 because in daylight, dolphins see the shark first.
168:03 Nighttime might be when all the action happens.
168:09 The team has a solution: a special night vision camera.
168:15 FRANCES: We know that tiger sharks are active at night.
168:17 The real question is,
168:19 how are they interacting with their prey at night?
168:22 NARRATOR: This camera can answer that question.
168:25 It uses infrared technology to peer into darkness.
168:30 KIRK: To my knowledge, there has never been
168:31 a nighttime deployment of a fin camera in Shark Bay.
168:35 NARRATOR: Night is when these two top predators
168:38 bring all their weapons to bear.
168:41 Their super-senses, echolocation in dolphins,
168:44 electroreceptivity in sharks,
168:48 allow both to keep battling after the sun goes down.
168:57 They head north where Captain Ash feels they have
169:00 the best shot at catching a big tiger at night.
169:06 FRANCES: So, we're just loading up the boat now
169:07 to go set some lines to catch our sharks at night
169:11 so we can put on our night camera.
169:13 So, we gotta go.
169:15 DUNCAN: A lot more swell this evening.
169:16 There's a big storm front coming in.
169:19 So, we've got a limited amount of time to get this tag on.
169:25 ASH: Go get a tiger, mate.
169:32 NARRATOR: If there's no shark,
169:34 they'll have to pull the lines before the storm rolls in.
169:38 FRANCES: So, right now, we're just looking for the buoys.
169:40 It's a little after 4:00 AM.
169:41 The wind has picked up.
169:43 So, fingers crossed, we get a big tiger really quickly.
169:47 NARRATOR: They're in luck.
169:51 FRANCES: You see it?
169:52 ASH: There it is, dead ahead.
169:54 FRANCES: We have a big old tiger shark on the line.
169:55 We're gonna work her up as fast as we can
169:57 and go from there.
170:00 ASH: Alright. Ready?
170:00 KIRK: Yeah. I'm on it.
170:03 FRANCES: It's big.
170:05 KIRK: It's a big female.
170:06 ASH: You want a hand or are you alright?
170:07 KIRK: Yup, coming down.
170:14 NARRATOR: Working a tiger shark is hard during daytime,
170:17 but downright dangerous at night.
170:21 Teeth and whipping tail...
170:25 all in darkness.
170:27 FRANCES: Stakes are high.
170:28 You know, we got one shot left at this.
170:30 So we gotta try to make it work.
170:32 KIRK: Watch out, coming up, coming up.
170:34 NARRATOR: Once again Duncan dives in,
170:37 this time in ink-black waters.
170:41 DUNCAN: Whenever you enter the water at night,
170:43 you've always gotta be concerned of not what you can see,
170:46 but what you can't see,
170:47 and when the lights go out, no one knows what could happen.
170:51 KIRK: Hold on.
170:53 FRANCES: Oh, (bleep).
170:54 KIRK: Watch it, Frances, watch it!
170:59 KIRK: Hold on. FRANCES: Oh, (bleep).
171:01 KIRK: Watch it, Frances, watch it!
171:04 NARRATOR: Shark researchers Frances Farabaugh
171:07 and Kirk Gastrich are wrestling a tiger shark.
171:10 KIRK: Coming down, breathing.
171:12 Okay, you good?
171:14 ASH: Yeah, I've got it.
171:16 NARRATOR: They hope to attach a special nighttime fin cam,
171:20 but an incoming storm and a thrashing shark
171:23 might make that impossible.
171:25 KIRK: Although there have been daytime camera deployments
171:27 in Shark Bay,
171:28 there haven't been any nighttime camera deployments.
171:31 Whatever we get back from this camera is gonna be novel stuff.
171:34 So now that we've got the shark alongside the boat,
171:36 we're going to finish our workup,
171:38 attach this nighttime camera,
171:40 and let her go, see what she sees.
171:43 FRANCES: Try to just get it down a little bit more.
171:45 KIRK: Watch out, guys.
171:48 NARRATOR: The whipping shark and the crashing swells
171:51 are not making it easy.
171:53 FRANCES: Come on.
171:55 KIRK: How we going with that, Frances?
171:57 FRANCES: Almost done.
171:59 NARRATOR: Their underwater cinematographer Duncan Brake
172:02 is capturing the action up close.
172:05 Sometimes too close.
172:07 KIRK: Dunc!
172:09 Watch it.
172:10 You got it?
172:12 DUNCAN: Every couple of moments, there'd be a massive surge
172:15 which would be pushing us right in towards
172:17 the jaws of that massive tiger shark.
172:22 KIRK: Far as you got it? Okay. Cool.
172:24 Frances got the tag on her, and she's getting restless,
172:27 so we'd better get her back in the ocean.
172:29 NARRATOR: The shark is ready to release.
172:32 They have to time it just right.
172:35 KIRK: Okay, ready? FRANCES: Ready.
172:38 KIRK: Ready?
172:39 ASH: Hang on, hang on.
172:40 Yeah, I'm ready.
172:41 FRANCES: He's ready. KIRK: Good?
172:42 ASH: Yeah. KIRK: Go.
172:44 ASH: You're off? KIRK: Off!
172:45 ASH: Right-io.
172:46 NARRATOR: A first:
172:48 a nighttime fin cam deployment in Shark Bay.
172:50 KIRK: Woo! ASH: Awesome.
172:52 FRANCES: Yeah, that's a pretty incredible experience.
172:55 So now it's just a race against time
172:57 to make sure that we get the tag as soon as it pops up,
173:00 and that we gather that data and get it back.
173:06 NARRATOR: But there's a problem.
173:08 ASH: Dead ahead, Frances.
173:09 KIRK: You got it?
173:10 FRANCES: Yep, got it.
173:12 So we were just headed on our way back into the boat
173:14 and the tag popped off.
173:18 NARRATOR: Instead of hours,
173:19 the camera releases after only a few minutes.
173:24 FRANCES: All of the, what you had hoped
173:25 and you did all this work for,
173:27 it's just defeat snatched from the jaws of victory.
173:30 You're so high and then you just drop so low.
173:37 So here you can see the animal and the boat.
173:46 And then floats back up towards the surface here.
173:51 Bummer.
173:53 NARRATOR: But there is a silver lining.
173:56 FRANCES: What this does is the night vision camera works.
173:59 We can see the animal's head.
174:01 And it's encouraging to see these, these images come back.
174:05 So it's something, an area for further exploration, for sure.
174:11 KIRK: Off!
174:13 It came back with our first glimpse
174:14 of some underwater nighttime footage from these tiger sharks.
174:18 You get confirmation that this technology could work.
174:21 NARRATOR: The battle beneath the waves of Shark Bay
174:24 remains hidden for now.
174:29 But Shark Bay does reveal something to the research team.
174:34 This war might not have winners and losers.
174:38 FRANCES: I think it's a mistake to think of this conflict
174:40 between dolphins and sharks as a zero-sum game.
174:44 When it's in balance,
174:45 you end up with a healthy, functioning ecosystem,
174:48 which is what we're looking to better understand and protect
174:51 and preserve as we move forward with a changing planet.
174:55 NARRATOR: This balance between the ocean's supreme predators
174:58 is revealed off the Florida coast.
175:01 A diver is in the middle of a bait ball.
175:04 This swirling mass forms as a defensive maneuver,
175:08 a way to confuse predators.
175:10 Predators like sharks and dolphins.
175:14 But here, they put their differences aside.
175:17 DUNCAN: So, when there's a big bait school in the water,
175:20 all these sharks and dolphins
175:21 are collectively working together,
175:23 collaboratively preying on all these little fish.
175:27 When the ocean provides, it's almost like the sharks
175:29 and the dolphins have called a ceasefire
175:32 so that they can meet in the middle and take down their prey.
175:36 NARRATOR: It's another glimpse
175:38 into the world of sharks and dolphins.
175:40 (man yells)
175:41 One more chance to gain insight
175:43 into their complicated relationship,
175:46 one that is changing how we view each animal.
175:50 FRANCES: It's a mistake to think of dolphins versus sharks
175:53 as some kind of mismatched pairing.
175:55 It's not one that's like a heavyweight champion
175:57 and one that's a lightweight, by any means.
175:59 DUNCAN: With sharks versus dolphins,
176:01 there's not ever a clear-cut winner or loser.
176:03 It's just nature.
176:10 NARRATOR: The waters off The Bahamas are a battleground.
176:14 In the war between sharks
176:18 and dolphins.
176:21 Using photographic evidence.
176:24 MIKE: One species that might cause that kind of bite
176:26 would be a bull shark.
176:29 NARRATOR: Specialized bite pads.
176:31 MIKE: It went through this simulated dolphin blubber
176:33 like butter.
176:34 NARRATOR: And, for the first time ever,
176:36 a decoy dolphin as their secret weapon.
176:40 These biologists will attempt to uncover
176:42 which sharks are the culprits.
176:45 MIKE: That dolphin is in big trouble.
176:48 They're coming right for it!
176:50 Yes!
176:52 NARRATOR: Shedding new light on these two apex predators,
176:56 locked in deadly underwater combat.
177:05 BOATER: Hey, they're fighting they're fighting.
177:06 Oh!
177:07 He's got a dolphin in its mouth!
177:09 It's right under us.
177:10 Look at the size of the thing.
177:12 NARRATOR: A bloody battle, as old as time,
177:16 is being waged beneath the waves.
177:20 Shark versus dolphin.
177:28 One of the front lines for this oceanic clash
177:31 is located 55 miles off of Florida.
177:37 Bimini is part of 700 islands that make up The Bahamas.
177:43 Nearly one third of dolphins here show signs
177:46 of shark attack.
177:53 A team of shark and dolphin researchers is here
177:56 to discover what sharks are targeting these dolphins,
178:01 the Atlantic Spotted Dolphin and the sleek grey Bottlenose.
178:07 KEL: We've got dolphins on the bow.
178:09 VALERIA: Wow, look at them ride.
178:13 NARRATOR: Dr. Mike Heithaus is a shark specialist
178:16 and a Dean at Florida International University.
178:20 He's joined by Dr. Valeria Paz, a dolphin expert,
178:24 and local Bahama dolphin researcher
178:27 Kel Melillo Sweeting.
178:34 First part of the mission:
178:37 photograph the scars to match them to the predators.
178:43 VALERIA: Hey, Mike. Did you see that notch
178:45 on that dorsal fin? MIKE: Yeah. You know
178:47 that couple notches there,
178:51 yeah, that's the kind of injury that could be caused
178:53 by a shark.
178:59 KEL: Two mother-calf pairs.
179:01 One of them had a distinct shark bite scar.
179:04 She actually got that injury as an older calf,
179:07 younger juvenile.
179:08 So what we're seeing now is a few years old,
179:11 really well-healed scar.
179:16 VALERIA: She came really close, so I was able
179:18 to get some really good footage.
179:22 NARRATOR: While foraging,
179:23 some dolphins occasionally break away
179:25 from the pod to crater feed.
179:29 Turning upright, using their nose,
179:32 or rostrum to dig and find prey.
179:38 This is when the dolphins are most vulnerable.
179:42 KEL: They have to remain vigilant because a shark
179:43 could be around at any moment.
179:48 We're also seeing signs of previous shark attacks.
179:54 One bottlenose dolphin had both pectoral fins injured.
180:00 MIKE: Here in the Bahamas, you can find more
180:01 than a dozen species of sharks.
180:03 But it's most likely the ones attacking dolphins
180:06 are the bigger bull sharks, tiger sharks,
180:10 and maybe great hammerheads.
180:12 These are the top predators here.
180:18 What a great snorkel. A couple mom-calf pairs.
180:21 There was one that it looked like had a bite
180:23 on the peduncle there.
180:24 KEL: Yes. Maybe a shark sneaking up from behind?
180:26 MIKE: Hopefully the pictures will help.
180:28 KEL: Yes.
180:31 NARRATOR: With so many large sharks in this area,
180:33 the dolphins have a lot of possible predators.
180:40 VALERIA: This bite is definitely on the side
180:41 of the flank so maybe it was trying to escape
180:43 or evade when it turned and then it got bit.
180:46 MIKE: Yeah, you see it's a pretty broad bite.
180:50 One other species that might be able to do that
180:52 something like the tiger shark,
180:56 they just have that big wide head compared to other sharks.
181:01 And then their teeth are really different.
181:03 You've got similar sized teeth in the top and bottom jaws.
181:07 Instead of being for puncturing
181:08 they're really meant for cutting.
181:10 And you've got really fairly long distances between the
181:13 teeth, so that should give us some clues.
181:17 KEL: This is a bottlenose dolphin,
181:19 took this photograph right around Bimini and you can see
181:22 it has a pretty fresh injury to its back here.
181:25 VALERIA: That's fairly sizeable.
181:26 MIKE: Yeah and it's super clean too,
181:29 so not a lot of diagnostics there and one animal
181:33 that could do that around here is the bull shark.
181:36 This is a replica jaw, you can see that's a big mouth
181:40 but with a clean bite a really big great hammerhead
181:43 might be able to leave a mark like that.
181:47 Now we just need to get impressions of shark bites
181:50 so we can get a sense of how they're holding
181:53 and gripping and releasing the prey and what that
181:55 would look like on a dolphin.
181:58 NARRATOR: There are 10 types of hammerheads,
182:01 but here in Bimini, the team sets out in search
182:04 of the great hammerhead to see
182:06 how it might be biting these undersea mammals.
182:11 Up to 20 feet Long, as large as a fully grown great white,
182:16 these giants congregate in the shallows off Bimini.
182:21 MIKE: These great hammerheads are huge sharks.
182:23 They have speed, maneuverability
182:26 and the teeth in the upper and lower jaw are different.
182:29 You get kind of cutting teeth on the top and gripping
182:31 teeth on the bottom.
182:33 So it's possible that great hammerheads are taking out
182:35 dolphin calves and if they get one of those in their mouth,
182:38 it's going to be really hard for that dolphin to get away.
182:46 NARRATOR: Mike and Valeria want to see
182:47 what great hammerhead bites look like on prey to compare
182:52 with the scars they've photographed on the dolphins.
182:58 Local shark diver Neal Watson has been working
183:01 with hammerheads here for more than a decade.
183:04 He's going to help the team get a bite impression.
183:08 NEAL: Today we're going to try and feed a whole bonito
183:10 to one of the hammerheads and the key difference
183:13 is we're going to try and actually get it back.
183:15 It's something unique that we don't do usually
183:17 but I think we'll be able to give it a shot.
183:20 MIKE: When we're gearing up to dive with sharks,
183:23 I'm really always running through worst possible cases
183:27 in my head, because you got to be prepared.
183:30 I'm always thinking about, okay,
183:31 if a shark is aggressive, what are we going to do?
183:34 Where am I going to be relative to Valeria?
183:37 What am I going to do if a shark comes around
183:39 from behind? You have to be really, really vigilant
183:42 whenever you're dealing with large, potentially
183:44 dangerous animals.
183:56 Great hammerheads don't attack humans,
183:59 but we're going to see how they feel about visitors.
184:05 NARRATOR: The smell of fish may entice the hammerhead,
184:08 but also bring in other species of sharks.
184:20 VALERIA: Tiger shark and I think I see some bull sharks
184:24 coming in.
184:25 NARRATOR: Tiger sharks and bull sharks are ambush
184:28 predators, known to sneak up on their prey,
184:32 so the team stays on high alert waiting
184:35 for the great hammerheads.
184:47 VALERIA: Those nurse sharks are definitely coming
184:49 to check us out.
184:51 And although their jaws might seem small,
184:55 once they bite onto something, they really hold on.
184:59 MIKE: We have to keep this fish away from them
185:02 or we might not get it back.
185:06 NARRATOR: Finally, the great hammerhead approaches,
185:10 and her size lives up to the name.
185:13 VALERIA: Wow, that is a beautiful shark.
185:17 Probably about 12 feet or more.
185:20 MIKE: Yeah, that's a large female.
185:25 Definitely big enough to eat a dolphin.
185:33 This hammerhead seems interested.
185:38 VALERIA: Hey Mike, tiger shark behind you.
185:44 MIKE: Here she comes!
185:52 Oh man she's trying to swallow it whole.
186:00 Well, there goes one bonito.
186:04 VALERIA: We've got another hammerhead.
186:13 MIKE: We've got to get the hammerhead to let go of
186:15 that fish.
186:23 Looks like the hammerhead is coming back around
186:25 for another go.
186:28 Okay, let it go, let it go! VALERIA: Yes, you got it!
186:35 MIKE: Let's get this up to the boat.
186:40 What an incredible dive.
186:42 VALERIA: That was unbelievable, those hammerheads.
186:44 The size of that one.
186:46 Must have been 12 to 14 feet maybe?
186:48 MIKE: Definitely capable of taking out a spotted dolphin,
186:51 maybe a bottlenose dolphin juvenile.
186:54 VALERIA: I'm excited to see that fish.
186:57 MIKE: Well, after all that we got one bonito head back.
187:01 VALERIA: Definitely scraped all the skin out.
187:03 MIKE: Yeah. It's not a clean cut
187:06 by any means and bonito is not a dolphin
187:09 but I guess if that was a hammerhead biting a dolphin
187:13 you wouldn't expect something clean.
187:14 It would probably be more scrapes through the tissue.
187:21 NARRATOR: The tearing bite of the hammerhead matches
187:23 the ragged scars seen on the dolphins.
187:28 VALERIA: That's definitely what we saw
187:29 when the hammerhead was approaching the fish
187:31 and it grabbed it and kind of teared.
187:33 It was not a clean cut. MIKE: No. So. We didn't
187:35 get tooth impressions like you might hope for
187:38 but it's some first clues.
187:41 For the sharks and dolphins here off Bimini,
187:43 they're pretty well-matched adversaries.
187:45 The sharks, body size, strength, cutting teeth.
187:50 And the dolphins live in groups, they're smart,
187:53 and they're super-fast and maneuverable.
187:56 NARRATOR: To observe just how intelligent dolphins
187:59 are Mike and Valeria head to the Clearwater
188:02 Marine Aquarium in Florida.
188:07 All of the dolphins here are injured or unable
188:10 to survive in the wild and cannot be released.
188:14 Animal care specialist Katie Wojdyla provides
188:18 daily enrichment.
188:20 KATIE: Right now I'm doing what we call face time
188:22 and all it is is a little playtime,
188:24 it's offering them any interaction
188:25 if they would like it.
188:27 We have right here in front of you is Hope.
188:29 She's currently 11 years old.
188:32 She really seems to enjoy water play.
188:35 NARRATOR: Animal care specialist Brooke Bowersox
188:38 has seen the damage sharks can do first hand.
188:41 BROOKE: This is PJ, you can see that she has a nice scar
188:43 back there on her peduncle.
188:45 MIKE: Yeah, and that just looks like a fresh bite
188:48 that we see on dolphins like the ones in Bimini.
188:50 You see that's not the only scar,
188:52 there's also places where it looks like the jaws come over.
188:55 VALERIA: Since the scar healed so well,
188:56 it's really difficult to tell what species
188:58 could've made that.
188:59 MIKE: Yes, a bull, tiger even great hammerhead,
189:01 you just can't tell from that healed wound.
189:05 NARRATOR: To avoid attacks, dolphins have an arsenal
189:08 of defenses, including intelligence.
189:12 With brain mass larger than any shark's,
189:15 dolphins are second only to humans in brain
189:18 to body weight ratio.
189:21 Making it easy for them to outsmart sharks.
189:25 But they also have a secret weapon to evade predators:
189:29 echolocation.
189:31 MIKE: Echolocation is really kind of a dolphin's
189:34 superpower.
189:35 VALERIA: Dolphins emit sound and they have a part of
189:38 their head that is called the melon.
189:41 This area receives the sound waves,
189:43 and it translates to what's going on
189:45 in their surroundings.
189:47 It allows them to navigate without using sight.
189:51 NARRATOR: Echolocation helps dolphins find prey
189:54 or detect predators.
189:59 MIKE: We're going to do an experiment to figure out
190:01 how we can use echolocation or how effective it is,
190:04 but first we've got to let him use all his senses.
190:06 What are we going to do? BROOKE: Yeah.
190:07 So this is a cognitive concept called the match to sample.
190:10 What we're going to do is we're going to show Nicholas
190:12 this buoy and then we're going to ask him to go across
190:15 to the other side of the pool where there's three
190:17 different sample items and ask him to select
190:20 which one matches what he's seeing here.
190:23 And you can see that he got it right.
190:26 MIKE: He did pretty well at that last one,
190:28 but now it's time to turn out the lights
190:29 and just do echolocation. How does this trial work?
190:32 BROOKE: So what we're going to do now
190:34 is we're going to place eye cups over Nicholas' eyes
190:36 and Bree is going to send him over to our right
190:38 with Katie is, where he's going to echolocate
190:42 on that red boat.
190:43 Once he echolocates on it, he's going to travel over
190:46 to where our samples are and they have those samples
190:49 under water. So using his echolocation,
190:52 he can make the correct selection.
190:54 MIKE: You see just no hesitation.
190:56 No worry about having his eyes, just echolocation
190:58 straight there.
191:01 BROOKE: Correct. VALERIA: And he did.
191:05 MIKE: It's incredible.
191:06 So, this really just shows how impressive
191:10 that echolocation is.
191:11 Also shows how smart they are and that smarts
191:13 and echolocation help them survive out in the wild,
191:16 including avoiding sharks. BROOKE: Absolutely.
191:21 NARRATOR: Back in The Bahamas, Mike and Valeria believe
191:24 hammerheads could be responsible for some
191:27 of the ragged bite scars they've photographed
191:30 on dolphins.
191:31 But they want to investigate another shark
191:34 that may be a predator.
191:36 And this one is second only to the great white
191:40 in the number of attacks on humans.
191:43 Tiger sharks.
191:45 Growing up to 18 feet, weighing nearly a ton
191:50 they'll eat just about anything
191:53 from tires to turtles. BOATER: No way.
191:57 NARRATOR: To dolphins.
191:59 New South Wales, Australia.
192:02 Off the coast of Newcastle, a tiger shark goes in
192:06 for the kill.
192:09 A lone dolphin is no match for the 11-foot tiger shark.
192:15 It disables its tail and the dolphin is dead in the water.
192:22 MIKE: Tiger sharks are incredible predators.
192:25 They also have teeth that are curved and have serrations,
192:29 so they cut in both directions.
192:31 So once they grab onto something,
192:33 they can shake their heads back and forth
192:35 and cut straight through it.
192:38 NARRATOR: And there's no place better to find tigers
192:40 than Tiger Beach, in The Bahamas.
192:45 The team will try to get bite impressions
192:47 from the tiger sharks and study the tiger's feeding
192:50 style to compare that with their photos of dolphins
192:54 with shark attack scars.
192:57 Underwater cinematographer Duncan Brake has been diving
193:00 these waters for more than a decade.
193:04 Neal Watson will be using whole bonito again
193:07 to get a bite impression.
193:19 Immediately, the team is met with an eager
193:21 group of tiger sharks.
193:26 MIKE: We want to get a tiger shark to bite the bonito
193:28 to examine how it uses those serrated teeth.
193:39 We've got one heading in.
193:44 VALERIA: There's a lot of lemon sharks coming in, too.
193:49 MIKE: Lemon sharks don't have much sense of personal space
193:53 and they can be aggressive eaters, so let's keep
193:56 the bait away from them.
194:00 NARRATOR: The lingering smell of the bonito fish starts
194:03 to catch the sharks' attention.
194:08 Two tigers approach.
194:11 MIKE: We usually think of tiger sharks as solitary
194:13 animals, but this fish has caught the interest
194:15 of more than a couple.
194:19 VALERIA: This one's definitely interested.
194:30 MIKE: Come on! Hold on! Yes!
194:36 NARRATOR: Neal manages to hold on to part of the fish.
194:41 MIKE: Let's get up to the surface.
194:49 VALERIA: That was incredible. Such large animals.
194:52 MIKE: No shortage of sharks. NEAL: None.
194:54 MIKE: And I think we're going to need bigger bonito
194:56 next time. NEAL: Yeah.
194:57 These are big three-foot bonitas but they're kind
194:59 of a one-bite meal for these tiger sharks.
195:03 I was able to wrestle this piece away.
195:05 I think it was indicative how they were feeding.
195:07 They would grab the bait and if they only got a little bit
195:10 of it they would let go momentarily to try
195:12 and get a little bit closer and I was able to pull it out.
195:15 MIKE: And that's what you see on the dolphins sometimes.
195:17 It's not just always a clean bite in but it looks like
195:20 there's bite and slash release bite again.
195:23 And that's kind of what you see here on that bonito.
195:26 VALERIA: Yeah. That's definitely similar
195:28 to the scars that Kelly showed us.
195:31 NARRATOR: The tiger sharks' slashing bite matches
195:33 what the scientists saw on the dolphins.
195:36 KEL: For a shark, a dolphin is no easy meal,
195:39 but is a really rich meal.
195:42 Lots of meat, lots of blubber.
195:45 But the dolphins have evolved to fight back.
195:49 MIKE: Once dolphins have seen a shark,
195:50 it's kind of the game's up for the shark,
195:52 it's not going be successful and the dolphins will
195:55 actually kind of chase and herd sharks away.
195:59 There's one video where a juvenile great white shark
196:02 approaches a group of dolphins and one dolphin
196:04 peels off and just chases that shark away
196:08 and the sharks just kind of, "Forget it.
196:09 It's not worth it," and it heads out.
196:14 These dolphins are not just swimming snacks for sharks,
196:17 they can detect sharks and kind of hold their own.
196:23 NARRATOR: Dolphins have one more advantage:
196:27 the ability to communicate with one another.
196:31 VALERIA: Dolphins are definitely chatty
196:33 and they use sound to communicate,
196:35 and it's really important to their everyday life.
196:40 KEL: We're observing some Atlantic spotted dolphins
196:42 and we're going to use this hydrophone,
196:44 an underwater microphone, to hear the sounds
196:47 through the headphones and hear their whistles, squeaks,
196:50 squawks, chirps.
196:51 Vocalizations are super important to dolphins,
196:54 to help keep track of the group, find food,
196:57 possibly even alert each other to predators like sharks.
197:04 NARRATOR: Even with echolocation and the ability
197:06 to communicate, dolphins in The Bahamas are still
197:10 under siege.
197:13 The team concludes that the ragged scars
197:15 they've seen on the dolphins could be from tiger sharks
197:18 and hammerheads.
197:21 But many of the scars they photographed were cleaner
197:24 and more defined.
197:28 Could there be a third species of shark attacking dolphins?
197:34 Bull sharks have the greatest bite force of any shark
197:38 relative to their body size.
197:42 Could they be responsible for preying on dolphins?
197:46 They prowl the shallow seas, using the sandy bottom
197:50 and murky water to conceal their attack.
197:53 Both dolphins and humans never see them coming,
197:58 until, it's too late.
198:04 MIKE: Here in Bimini, the bull sharks
198:06 and the dolphins are often hunting in the same areas,
198:10 and that can include murky waters.
198:13 The bull sharks are probably mainly hunting for smaller
198:16 things, but if they get a chance to grab a dolphin,
198:18 they're going to take it because that dolphin
198:20 represents an incredible meal with all the fat
198:23 and energy in the blubber.
198:25 NARRATOR: The team needs a bite impression
198:27 from the bull shark to compare to the dolphin scars.
198:32 But this time they'll attempt something
198:34 that's never been done before.
198:37 They're creating a life-sized dolphin decoy,
198:42 but first they need to test out the material
198:44 they'll be using to make the dolphin,
198:48 while also collecting more bite data.
198:51 MIKE: This is basically a gelatin block
198:54 that is the density of dolphin blubber
198:56 and we've turned it into a giant underwater lollipop.
199:01 So what we'll do is put a little bit of fish on this
199:04 to entice a shark to bite.
199:05 And when they bite it, it's going to give us
199:07 a jaw impression.
199:10 NARRATOR: They head to the waters between Florida
199:12 and Bimini.
199:14 MIKE: This is the perfect place to come
199:16 to find bull sharks. There's lots of food here,
199:18 the water temperatures are right
199:20 and it's a known spot where groups of bull sharks
199:22 get together.
199:24 NARRATOR: While Mike gets the bite,
199:25 Valeria will be on shark measuring duty.
199:29 A laser device can pinpoint the exact length
199:32 of the shark.
199:40 MIKE: Bull sharks have a reputation as a more
199:43 aggressive species, but they usually don't bother divers.
199:49 But we do have bait on the pad here,
199:52 so we've got to stay alert. VALERIA: Copy that.
200:05 A couple of bull sharks are coming in.
200:14 I'm going to get some measurements.
200:20 They look definitely the size that would attack a dolphin.
200:23 MIKE: They're interested in the fish,
200:26 but they're being cautious.
200:37 VALERIA: They're definitely curious, just not biting.
200:41 MIKE: Wait. This one's coming back around.
200:45 VALERIA: Watch out, your hands!
200:49 MIKE: Didn't even see it. (bleep)
200:54 I count three bull sharks.
200:57 They're all more than 6 feet long.
201:01 I'd say they're big enough to attack a dolphin.
201:03 We just need to get one to bite this pad.
201:13 Oh, that was close!
201:18 VALERIA: We need a good bite and the size of the shark,
201:21 to compare it to the bite marks on the dolphins
201:23 in Bimini.
201:25 MIKE: Wait a minute.
201:28 I think we have another taker!
201:34 I can't hold it!
201:40 VALERIA: That bull's coming right back around Mike.
201:50 MIKE: Get the lasers ready.
202:07 VALERIA: Yes, we got it!
202:19 MIKE: Look at that. Oh, this is incredible.
202:23 You just see the width of that bite,
202:27 it just bit on and went through this simulated
202:30 dolphin blubber like butter.
202:37 You can see why dolphins just lose big chunks
202:42 if a big shark gets a hold of them, and that one,
202:45 we got a really nice laser hit on.
202:46 So we'll know exactly how big the bull shark
202:48 was that did that.
202:52 And we got a bonus. This shark left a tooth behind.
202:58 They lose so many teeth in their lives.
203:00 They're constantly shedding. So
203:01 a loose tooth, even in dolphin blubber can get stuck.
203:05 Usually, we're not so lucky to have them left behind.
203:08 A nice bite width there on a real-world situation.
203:11 So this is exactly what we wanted, I am psyched.
203:16 NARRATOR: The bite pad reveals that the ragged bite
203:18 marks from the photos were probably not caused
203:21 by the bull shark.
203:24 The precise incision on the pad could mean bull sharks
203:28 are the ones leaving the cleaner scars.
203:32 But there's another way to find out whether
203:34 these bull sharks have attacked
203:36 the underwater mammals.
203:39 MIKE: Right now we're trying to catch a bull shark.
203:41 We got a piece of bonito on a small circle hook
203:43 so we can throw it to the bull shark that we want,
203:47 catch it, get it up, and see if it's eaten a dolphin.
203:51 NARRATOR: In sharks, the reproductive and digestive
203:53 systems come together at a common area called
203:56 the cloaca, so the team will take a sample from this area.
204:02 VALERIA: So here's the swab kit.
204:03 We're going to be using the cotton swabs to get fecal
204:06 matter from the bull shark and that will tell us
204:09 a little bit about what they have been eating.
204:12 That is going to be really useful to see if we see
204:14 any dolphin DNA in this fecal matter.
204:17 MIKE: First, we have to catch one.
204:24 Handling sharks can be really dangerous
204:26 if you're not careful and that's especially true
204:28 for bull sharks.
204:29 They got that big mouth, sharp teeth,
204:31 but the tail is incredibly powerful.
204:34 So you've got to always be aware of your surroundings
204:36 and work together as a team.
204:41 There we go.
204:42 Okay there's a bull shark right below us.
204:44 VALERIA: See it.
204:48 MIKE: They're right next to it.
204:49 Yes, it's on, it's on it, it's on it.
204:52 VALERIA: Oh. Nice.
204:55 MIKE: Okay now I need everybody to be beyond
204:56 careful right now. -Yeah.
204:59 Right down there. It's a good sized one for sure.
205:04 Watch your feet, watch your feet.
205:07 That is a big bull shark.
205:10 VALERIA: Oh. It's a big one.
205:13 MIKE: Fresh shark, the trick now is to hold on
205:16 as much as you can.
205:25 Ah!
205:30 That is definitely big enough to attack a dolphin.
205:33 No question.
205:36 Okay. Get ready.
205:39 I'll start back further, try to bring it around.
205:46 Well, we're trying to get a tail rope on it so we get.
205:49 VALERIA: I got you. I got you. I got you.
205:52 MIKE: Slow, slow, slow, you're good, you're good,
205:53 you're good. Nice and easy.
205:57 Oh close.
206:00 Okay. Excellent.
206:04 Okay. Good job. Okay.
206:07 Now, we've got control of the animal, so now, cleat that off.
206:11 A little bit lower. A little bit lower,
206:12 so its tail's kind of in. Good.
206:15 NARRATOR: But just as they're about to tie the shark off.
206:19 MIKE: Oh no, look out, look out, clear clear, clear!
206:23 Look out. Careful. Careful.
206:30 No, do not grab this.
206:31 It popped the monofilament.
206:34 NARRRATOR: They've lost control of the most
206:35 dangerous part of the shark, its jaws!
206:39 MIKE: Back off! Back off!
206:45 MIKE: Agh!
206:47 No, do not grab this.
206:48 It popped.
206:51 We had the shark actually drop when there was a swell and it
206:54 popped that monofilament, so we're just going to do a quick
206:57 repair on the fly, so we have control of the animal here.
206:59 I need another roundy. I'm going to tie into this,
207:03 and get the crimping tool. VALERIA: I got it.
207:06 MIKE: We've got to write down the lengths.
207:09 Mark that, 216.5. VALERIA: 216.5.
207:14 MIKE: 252. That's about 8 and a half foot Bull Shark.
207:17 That's definitely big enough to go after a dolphin. Okay.
207:20 Get the cloacal swab kit. VALERIA: Yup.
207:22 We are going to be opening up the swab kit and making sure
207:26 that everything is set up for the cloacal swab.
207:31 Make sure this is up so that it's out of the water.
207:34 MIKE: Okay. VALERIA: All right.
207:35 MIKE: Great job. That's perfect.
207:39 VALERIA: Here we have the vial.
207:40 We're going to go ahead and place it in here
207:42 and make sure to label it and we'll send it out to
207:44 the lab to find out what sharks have been eating.
207:47 MIKE: Okay, we can release any time.
207:50 NARRATOR: Releasing an angry shark is even more dangerous
207:52 than catching it.
207:55 The crew has to be careful not to get caught
207:58 in the lines as it thrashes.
208:01 MIKE: Look out.
208:03 Okay. Hang on. Hang on, hang on.
208:06 Are we ready?
208:08 here we go. Three, two. One.
208:14 Great, great. Good job.
208:18 That was great.
208:20 We got that shark up, tag in, cloacal swab done,
208:23 and a great release.
208:26 The cloacal swab showed us these bull sharks hadn't
208:28 eaten a dolphin recently, but that doesn't mean
208:31 they're not dolphin predators.
208:33 It just means they're not eating them all the time.
208:36 NARRATOR: The cloacal swab was inconclusive
208:39 but the bite pad shows that bull sharks could be the ones
208:42 making the clean bites seen in the photos.
208:47 Mike and team are now ready to deploy their nearly
208:50 200-pound secret weapon.
208:53 They want to get an even more realistic view of what
208:56 a bull shark bite would look like on a real dolphin.
209:01 MIKE: This is Gooey, our dolphin model and Gooey
209:05 was made out of non-toxic gelatin.
209:07 We want to make sure if a shark gets a mouthful
209:10 of Gooey, it's completely harmless to the shark.
209:13 Gooey was made so that the consistency is exactly
209:16 like that of dolphin blubber.
209:18 And it's pretty much the same size as an Atlantic spotted
209:21 dolphin in Bimini or a juvenile bottlenose.
209:24 NARRATOR: This is the first time a dolphin decoy
209:27 made of non-toxic materials will be used
209:30 in shark research.
209:32 MIKE: The bite-pads were a great first step,
209:36 but they're just kind of a fairly narrow pad
209:39 and so a shark might bite that very differently
209:42 than something that's shaped like a dolphin.
209:45 It's rounded and in some places it's so big
209:47 that it's kind of like trying to palm a ball
209:49 that's too big for a shark trying to bite it.
209:51 So we have created something completely unique,
209:55 a gelatin dolphin.
210:00 NARRATOR: It's sink or swim time for Gooey.
210:03 The team takes her to an area known for bull sharks.
210:07 They're joined by underwater cameraman Sean Havas,
210:11 who will capture this "first" in shark research.
210:14 MIKE: As soon as Sean and I are in let's get Gooey
210:16 in right next to us. VALERIA: You got it.
210:18 I'll be looking at you guys for directions.
210:20 Once I put it in if you need me to give it some life.
210:23 MIKE: We'll let you know but hopefully Gooey
210:25 will do its job.
210:33 VALERIA: We're strapping a camera onto Gooey to get
210:35 a better angle.
210:36 We're positioning it so that it faces the peduncle area
210:40 where we think sharks may be more enticed to bite.
210:44 Mike, should we deploy Gooey?
210:46 MIKE: Ready for Gooey.
210:50 VALERIA: Copy. We'll deploy. You got it Mike.
210:52 NARRATOR: Deploying this enormous dolphin decoy
210:54 takes teamwork.
210:56 VALERIA: Kirk, look at the camera.
210:57 Make sure it's at the right angle when it gets deployed.
211:00 Lucas, make sure that the pectoral fins are not getting
211:02 stuck by the ladder, and let's do this.
211:06 All right. Please clear the deck.
211:09 One, two. Slide.
211:24 MIKE: All right.
211:26 Gooey's swimming.
211:30 VALERIA: Mike, what are you seeing down there?
211:33 MIKE: Well, right now, it's pretty lonely.
211:36 Just hanging out with Gooey. No sharks yet.
211:39 So hopefully, we get some interest soon.
211:43 VALERIA: Gooey right now doing a natural behavior.
211:45 This is called logging. Logging is when
211:48 they're resting and there may be more vulnerable
211:50 during this behavior.
211:53 MIKE: We got Gooey exactly where we need it to be.
211:58 It looks so real!
212:01 VALERIA: Gooey is of similar size of those dolphins
212:03 that we saw in Bimini.
212:04 Although her colorations are a lot different,
212:07 the silhouette from below mimics
212:09 that of a real dolphin.
212:11 NARRATOR: Sharks are attracted to contrast.
212:14 They may not see color,
212:16 but this silhouette should lure them in.
212:19 If one attacks, Mike will not only get a bite impression,
212:23 but the exact size of the shark.
212:27 They'll be able to record if smaller juvenile sharks
212:30 might attack a dolphin, or is it mostly
212:33 the larger mature sharks.
212:36 MIKE: The idea is, we want to get length on the shark
212:40 that attacks Gooey so we know not just what species
212:43 grabbed the model, but how big it was.
212:49 NARRATOR: The bull sharks arrive.
212:53 And it's time to put Gooey to the test.
212:56 Will she be a trick or treat for the bulls?
213:00 MIKE: These are big bull sharks.
213:03 They are definitely a threat to the dolphin.
213:09 We've got four sharks, they're circling
213:12 but we're not seeing a whole lot of interest right now.
213:15 Try giving Gooey some motion.
213:17 VALERIA: Copy Mike, will give it some movement.
213:22 Kirk, can you please give it some motion?
213:26 MIKE: No. Still not interested.
213:29 That's not terribly surprising since bull sharks
213:34 probably only very, very occasionally attack
213:38 dolphins that they see.
213:42 She looks like a dolphin and kind of moves like a dolphin.
213:47 Maybe we need to add some smell.
213:50 Sharks have an incredible sense of smell.
213:52 They can smell a couple of drops of blood in a swimming
213:54 pool worth of water.
213:56 That means that if there's a good scent trail,
213:58 they can follow it for miles.
214:05 Now one is starting to move toward it.
214:08 Come on! No. Okay.
214:13 We may have to do a bit more than this.
214:15 We're going to come up and think about what
214:17 our next steps are to try to get a bite here on this model.
214:20 VALERIA: Copy that. Let's pull her in.
214:28 VALERIA: So we're bringing Gooey in.
214:29 Her silhouette looked really good underwater,
214:32 but sharks used multiple senses to detect prey,
214:36 so we're going to add a little something to see if we can
214:37 entice them to bite Gooey. One two three, pull.
214:43 NARRATOR: The team has one more trick up their sleeves
214:46 to try and get a shark to bite Gooey.
214:49 MIKE: Gooey almost looks real when you're far enough below.
214:53 We had the sharks around,
214:54 but they didn't really show any interest in the dolphin.
214:57 VALERIA: We know sharks don't bite every single dolphin,
214:59 so we need to add something to entice them.
215:02 MIKE: What I think we should do is strap a bit of bait
215:04 down here. Then when the sharks come in at the bait,
215:07 they try to grab the bait, and they're going to grab
215:09 Gooey as well right in an area
215:10 where we see bites on a lot of wild dolphins.
215:14 NARRATOR: The team attaches bait to the area
215:17 where they've seen many bite scars, the peduncle,
215:22 to see if a bite here will match what they've seen
215:25 on the wild dolphins.
215:27 VALERIA: The peduncle is a really strong muscle
215:29 at the tail end of the dolphin, and it allows them
215:32 to move their tail really fast, it allows them
215:34 to maneuver, and get to great speeds.
215:38 KEL: The peduncle is where the dolphin's
215:40 power is for swimming. If it gets a serious
215:43 enough injury or if the spinal cord is severed
215:46 or damaged, then that dolphin might become
215:49 incapacitated, giving the shark a second chance
215:52 to come in for the kill.
215:54 MIKE: Echolocation and vision, most of that
215:57 for the dolphin is directed forward.
215:59 So coming from below and behind is the easiest way
216:02 to sneak up and make that ambush attack.
216:06 As the sharks come in to get a bit of food,
216:08 they're going to bite the dolphin model,
216:10 and we'll get those really nice tooth impressions
216:12 once they've bitten in. VALERIA: Definitely,
216:14 adding the bait, that extra scent will really entice
216:17 the sharks to bite Gooey.
216:23 Ready. Let's do this.
216:27 NARRATOR: Gooey not only looks good,
216:29 she smells good too.
216:31 MIKE: We've got one coming in!
216:33 A shark coming up from this angle from below and behind.
216:36 That dolphin is in big trouble.
216:41 There's definitely sharks more interested now
216:44 that there's some fish on Gooey.
216:47 VALERIA: It's coming in close.
216:48 We definitely have their attention.
216:50 MIKE: They're going right for it!
216:53 Look at that.
216:55 (Excited screams)
217:01 Yes! That is exactly what we wanted.
217:04 Let go now please.
217:08 Man that bull shark just nailed Gooey.
217:16 VALERIA: Whoa, look at that.
217:18 MIKE: It's incredible, isn't it?
217:19 You can see where each tooth just traces through,
217:22 even the serrations on the teeth.
217:24 VALERIA: This could have definitely been fatal.
217:26 MIKE: Oh yeah, it almost nicked the spine.
217:28 There's too much vital there. This dolphin would have
217:30 bled out, and the shark could have come back later
217:32 to finish it off.
217:33 VALERIA: Good job, Gooey. Let's pull it up.
217:35 MIKE: It's pretty incredible just how much that shark
217:40 got out of Gooey. I mean. That was probably 20 pounds
217:42 of gelatin. That was a stunning success.
217:45 It actually simulated real life more than we would've
217:47 thought because Gooey was kind of listing to the side.
217:50 And if a dolphin sees a shark coming,
217:52 it's going to turn its back to it to try
217:54 to maneuver away. And so the shark came
217:56 straight from the bottom up and bit here.
217:58 It would've gone right next to the spine and you can see
218:01 a nice clean cut, and so an 8.5-foot bull shark,
218:05 no problem killing a dolphin.
218:10 Gooey really taught us a lot.
218:12 From just one bite we were able to see that even
218:14 with this big round object a bull shark leaves
218:17 a clean bite not a ragged one.
218:20 With the 3D-scan were we able to see how each tooth
218:23 moved through and that these bull sharks are leaving
218:26 clean bites even on big round dolphins and it really
218:29 showed us that it's going to take a big adult bull shark
218:32 to take down a dolphin.
218:35 Evolution tends to hone behaviors that make
218:39 predators super-efficient, and prey good at getting away.
218:42 For dolphins, if they aren't paying attention
218:45 and good at avoiding predators, they're not going
218:48 to leave many calves in the next generation.
218:50 And so that arms race between predator and prey is going
218:53 to continue for sharks and dolphins.
219:00 NARRATOR: The evidence collected with the bite pads
219:02 and dolphin decoy suggests that hammerheads,
219:07 tiger sharks and bull sharks could all be responsible
219:13 for the bites seen on dolphins here.
219:16 And still, the battle of The Bahamas between
219:19 some of the best designed and most intelligent species
219:23 in the ocean rages on.
219:26 KEL: The fact that there are so many sharks
219:28 and so many dolphins in the Bahamas might be a really
219:32 good sign for the health of the oceans here.
219:35 You have food all year round, mates all year round
219:38 and even when a dolphin gets bit by a shark,
219:41 if it's lucky enough to get away,
219:43 it's healthy enough to survive that attack.
219:47 VALERIA: This clash between the predators,
219:48 there's no winners or losers.
219:50 It's just the opportunity to catch a prey.
219:53 MIKE: We have great hammerheads, we have
219:54 tiger sharks, we have bull sharks, all in this one spot
219:58 and there're dolphins there too.
220:00 This battle between sharks and dolphins in the Bahamas
220:02 isn't going to end.
220:12 SARA: Mike, you got a couple coming on your stern right now.
220:15 MIKE: There's one right here.
220:16 SARA: It might get more interested.
220:18 NARRATOR: Shark scientists, Dr. Mike Heithaus and Sara Casareto,
220:22 are about to reveal why sharks seem to attack boats,
220:25 from fishing trawlers to tiny kayaks.
220:29 SARA: Once Mike casts that line, I'm expecting the moment
220:31 that fish hits the water for the sharks to be all over it,
220:34 and as he's reeling that in,
220:35 we're gonna see a lot faster behavior.
220:37 MIKE: Okay. Ready?
220:39 SARA: You're good.
220:43 MIKE: Bait's out.
220:45 That one just bumped me.
220:46 Okay. This one's coming fast.
220:48 SARA: That shark is coming in hot.
220:50 Pull in that fish, Mike.
220:52 MIKE: Ah!
221:02 NARRATOR: It was understood, if you stayed on a boat,
221:05 you'd avoid a terrifying confrontation with a shark.
221:09 That's not true anymore.
221:13 STEVE: Holy! JEFF: Oh, my God!
221:14 STEVE: Watch out! JEFF: That thing is huge!
221:16 ERIKA: He chomped on the boat!
221:20 NARRATOR: Erika Almond was fishing off the Gulf Coast of Florida
221:23 on a 34-foot boat when a great white shark took interest.
221:28 MAN: No way.
221:29 ERIKA: Holy moly.
221:31 That's huge.
221:32 Great white.
221:33 Wow.
221:35 When we first saw the shark as it came closer, we were able
221:37 to estimate it to probably about 14 to 16 feet.
221:40 Now, we've all seen Jaws and we know the outcome of that.
221:43 NARRATOR: Great white sharks are rare in the Gulf of Mexico,
221:46 which made the encounter even more terrifying.
221:51 ERIKA: As the shark was coming at the motors, if it hit
221:53 underneath with the prop or on the back itself, you could
221:56 almost hear the teeth scrape against the metal of the
221:59 actual motor itself.
222:01 MAN: Biting the engine.
222:07 ERIKA: I thought, "Oh, my gosh.
222:09 We're gonna need new motors or a paddle to get us out of here
222:11 because they're going to be gone."
222:13 Oh, God.
222:16 Watch your hand.
222:18 We could not believe what we had just encountered and
222:21 been a part of.
222:22 I didn't know that that was something that sharks would do.
222:25 Wow. Great white.
222:29 NARRATOR: Erika's encounter is not unique.
222:32 Many boaters have the same showdown with sharks.
222:38 Dr. Mike Heithaus and shark biologist Sara Casareto are
222:42 off the Florida Coast to investigate why these
222:45 frightening interactions take place.
222:49 MIKE: You go online these days and you see more and more
222:51 videos of sharks biting boats or just getting uncomfortably close.
222:55 And the question is is that just more people with cameras
222:58 or is there something going on with the sharks?
223:02 And that's something we're out here to investigate.
223:05 SARA: A lot of boating activities involve sensory
223:08 stimulation that can actually pique sharks' interests.
223:11 It involves splashing, a lot of times you're out on a boat
223:14 and you're fishing or there's chum in the water.
223:17 Holy (bleep).
223:19 SARA: And all of those things could attract a shark.
223:23 So we're heading about three miles off the coast of
223:25 Palm Beach where the water depth is about 100 feet.
223:28 This is an area with a lot of boat activity and there's been
223:30 reports of shark interactions.
223:33 MIKE: Florida is an incredible place for sharks.
223:35 One reason is we have so many habitats in such a small area.
223:39 You've got mangrove forests along the coast, seagrass beds,
223:42 coral reefs, and deep water that comes close to shore.
223:45 That means all the different species that are in these
223:48 areas can kind of mix.
223:50 So you've got nurse sharks, lemon sharks, bull sharks,
223:54 tiger sharks.
223:55 Even great whites come through here.
223:59 NARRATOR: They set up shop three and a half miles off the
224:01 coast to explore why sharks are attracted to boats.
224:06 In addition to the two biologists,
224:07 cinematographer Duncan Brake will document the shark's
224:10 behavior from below the surface.
224:14 He's filmed sharks all over the world and has had
224:17 his share of boat-shark encounters.
224:21 DUNCAN: One of the craziest interactions I've seen with a
224:22 shark and a boat was when we were following a bull shark
224:25 that we'd seen cruising along the coast.
224:27 As soon as we approached it, it decided it didn't want us
224:31 in its space, and it turned around and just went straight
224:33 for the engine and did three or four bites before it turned
224:36 around and, and swam away.
224:38 At which point, we decided we were gonna back off
224:40 and leave it be.
224:43 SARA: All good, Duncan?
224:44 DUNCAN: All good.
224:45 SARA: All right.
224:47 MIKE: You're clear.
224:52 NARRATOR: The team's first mission is to reveal why
224:54 sharks suddenly circle boats.
224:58 MIKE: We're here on the spot but no sharks yet.
225:00 SARA: Any sharks down there?
225:06 NARRATOR: Duncan is in the water with an underwater comms
225:09 to relay anything he observes.
225:11 SARA: Copy that, Duncan.
225:13 So, Mike, Duncan wants us to start revving that boat
225:15 engine, see if we can draw some of those lemon sharks
225:17 in with the sound.
225:18 MIKE: Okay. Sounds good.
225:20 Sound travels an incredibly long distance underwater and
225:23 sharks have amazing hearing.
225:25 So, you know, if they're not doing something else,
225:27 that might attract them in.
225:29 Okay.
225:30 Ready to rev. He's clear.
225:32 Engine's in neutral.
225:33 Revving.
225:38 SARA: Duncan, I'm looking and I don't see anything.
225:40 Do you see anything from your end?
225:46 SARA: Copy that.
225:47 Crystal clear water, Duncan.
225:49 MIKE: Sharks don't have ears like us but they can still
225:51 hear incredibly well.
225:53 They even have special cells on their body that can feel
225:55 vibrations, whether it's sound or the movement of
226:00 animals through the water.
226:02 SARA: That boat engine has really equated to, for a lot
226:05 of the sharks in the area, the ringing of a dinner bell.
226:08 They hear that and they think, "Free meal."
226:15 MIKE: Okay I think we got one coming in right here.
226:20 DUNCAN: I spent a lot of hours in the water with lemon sharks.
226:22 There's one thing for certain, no matter the size,
226:24 you've got to be on guard.
226:28 They can spin on a dime.
226:30 They have amazing maneuverability, being able
226:32 to turn right around and almost bite their own tail.
226:40 MIKE: Lemon sharks are a pretty cool species.
226:42 You know, it gets to be nine or ten feet long.
226:44 They're pretty intimidating in size when you're underwater.
226:46 They're also pretty intelligent sharks.
226:49 You know, they've been trained to run mazes.
226:50 And you can see, when they're underwater and you're swimming
226:54 with them, they're really figuring things out.
226:56 But the other thing about lemon sharks when you're
226:59 diving at least with them, no sense of personal space.
227:02 They just kind of bump straight past you.
227:04 They're not attacking.
227:05 They're just going where they go.
227:12 NARRATOR: Within minutes, two lemon sharks become a dozen.
227:16 The only bait in the water, a rumbling engine and
227:20 Duncan's scuba bubbles.
227:37 SARA: The lemon sharks in this area are majority
227:39 female hanging out.
227:40 MIKE: And you never expect to see the little ones out here.
227:44 NARRATOR: While the sharks circle, Dr. Heithaus and Sara
227:47 reveal why they believe sharks are biting boats.
227:51 MAN: Watch out!
227:52 MAN: It's a huge one!
227:54 NARRATOR: Videos of sharks gnawing on hulls abound.
227:57 JEFF: Ah!
228:01 STEVE: Oh, my God!
228:02 Oh! (bleep)!
228:04 SCOTT: Jeff, let it go.
228:07 NARRATOR: Steve Minkema and his buddies, Jeff Crilly and
228:09 Scott Crilly, were fishing off the New Jersey shore
228:12 when a great white decided to show them how its jaws work.
228:19 JEFF: Oh, my God!
228:21 This thing is huge!
228:22 This thing, holy (bleep)!
228:25 STEVE: Oh, my God!
228:28 SCOTT: We were all set up.
228:29 STEVE: All excited to catch a big fish.
228:31 I forgot who saw it first.
228:33 JEFF: Ah!
228:35 This thing is huge!
228:36 STEVE: I remember you saying, "Holy crap.
228:38 This thing is big."
228:39 JEFF: Massive.
228:40 Half the size of the boat.
228:42 SCOTT: He comes up on this side.
228:43 JEFF: Right for the chum bag here.
228:46 Just opens his jaw and grabs it.
228:49 STEVE: He's going for the chum bag.
228:50 JEFF: Ah! (bleep)
228:55 SCOTT: Let it go!
228:56 JEFF: Ate our chum bag like.
228:57 SCOTT: Yeah.
228:59 JEFF: You said like a Tic Tac. SCOTT: Like a Tic Tac.
229:00 JEFF: (bleep)! Holy! Oh, my God!
229:03 Holy (bleep)!
229:04 STEVE: He came right up.
229:05 He's scraping on the back of the boat.
229:07 His teeth are grinding into the back.
229:09 JEFF: It was chomping like this.
229:11 He's going for the chum bag.
229:12 Ah!
229:13 I don't think he could have bit through the hull,
229:14 but like the size of him and the weight of him,
229:17 I think if he really wanted to,
229:18 he could have pushed in and swamped the boat.
229:22 SCOTT: Jeff, let it go. JEFF: Holy (bleep)!
229:23 STEVE: Once he got what he wanted, he, he just swam away
229:26 like nothing happened.
229:27 JEFF: Dude, that was the coolest (bleep) thing
229:29 I've ever seen.
229:31 Monster majestic shark.
229:34 STEVE: Yeah.
229:35 Something you'll never forget, right?
229:36 JEFF: No. Once in a lifetime.
229:38 Ah!
229:40 Oh, my God, dude!
229:44 MIKE: One thing you see in just about every viral video
229:46 of sharks attacking boats is one of these.
229:49 It's a chum bag.
229:50 Basically a mesh bag with bait in it.
229:52 Fishermen use it to attract fish in so they can catch them.
229:56 We're gonna do the same thing but for sharks so
229:58 we can study them.
229:59 So we're gonna put this in here, off the back.
230:02 Sara, you can throw yours in now.
230:06 SARA (over radio): Hey, Duncan, we're about to put the chum bags
230:07 SARA: In the water, so keep an eye out for the shark behavior
230:10 to possibly change.
230:15 SARA: We've just put essentially a meal in the
230:17 water for them and they're just trying to get that.
230:19 So we should see lemon sharks coming up, biting the chum bag,
230:22 and appearing to bite the boat but, in reality,
230:24 they're just trying to get the fish in the bag.
230:27 NARRATOR: The sound of the boat engine draws in a shark,
230:30 but it's the scent of the bait that revs them up.
230:39 MIKE: Whoa!
230:40 It pulled it out of my hand.
230:42 Luckily, it didn't get any bag but it almost did.
230:45 So you can see how quick this happens.
230:47 If you're not expecting sharks around, it could be pretty
230:49 surprising to have one appear at your chum bag.
230:55 SARA: When we just have the sound of the engine,
230:57 the sharks were just cruising.
230:58 They were hanging out, checking to see if anything
230:59 was coming up.
231:01 But once we put chum in the water and we put fish in the
231:03 water, they start going to more of a hunting mode,
231:06 and that's when their movement gets quick.
231:08 It gets erratic, and sometimes it can be very unpredictable.
231:12 NARRATOR: This aggressive behavior could mean trouble
231:14 for Duncan down below.
231:17 DUNCAN: If you see them swarming all around us,
231:19 it definitely gets the adrenaline going.
231:21 What you have to do is try to make sure you don't get
231:23 between them and the food.
231:32 NARRATOR: A chum bag might explain why sharks swarm boats
231:35 and also why they sink their jaws into them as well.
231:46 MIKE: You can see the way it pulled the bag out of the water,
231:48 the shark missed it, bumped into the boat.
231:50 That could look like an attack in the right viral video.
231:53 But what's going on is that the shark's just missing.
231:56 And they have what's called a nictitating membrane.
232:00 SARA: Sharks have this defense to protect their eyes, which
232:02 is kind of like an eyelid that closes up.
232:04 Some sharks roll their eyes to the back of their head 'cause
232:07 the back of their eye is actually a lot thicker and denser.
232:12 And in that moment, they're blind.
232:22 MIKE: So at the last second before it hits the boat,
232:23 it's kind of losing that sense of vision, and that may be
232:26 one of the reasons that we see these sharks attacking boats.
232:34 SARA: If what they were going for, let's say a chum bag,
232:36 moves 'cause of a wave or the fisherman pulls it out, they
232:38 still have that propulsion forward.
232:40 They're gonna maybe bite the boat and they might just miss.
232:42 Oh!
232:47 NARRATOR: With so much chum in the water, the researchers
232:49 question whether sharks are too dependent on bait for food.
232:54 The team will catch a shark and take a blood sample.
232:58 SARA: With the blood, we're breaking it down into plasma
233:00 and red blood cells.
233:01 We're then gonna do what's called an isotope analysis,
233:04 where we look at the chemical composition of these
233:06 components, to get a sense of what these sharks are feeding
233:09 on and how much of it might be chum and bait.
233:13 NARRATOR: The team sets up a catch-and-release.
233:16 MIKE: One, two, three.
233:20 NARRATOR: The time the shark is immobilized is kept to a minimum.
233:25 MIKE: The way we're trying to catch these sharks is designed
233:27 to minimize stress to the animal.
233:29 We're using a relatively small circle hook.
233:32 That let's us catch the shark right in the side of the jaw,
233:34 and these sharks heal incredibly quickly.
233:36 This really shouldn't hurt the shark at all so they're back
233:38 to their normal behavior right away.
233:42 Nice.
233:43 The shark has it.
233:44 SARA: Right now, one of the sharks have got our hook.
233:47 We're gonna let it run with it so it tires itself out and
233:49 it'll become easier to.
233:50 MIKE: There we go. SARA: Pull in.
233:53 MIKE: Okay.
233:55 We're gonna pick up the buoys here, gently bring the shark
233:57 up next to the boat, get it swimming along side.
234:01 DUNCAN: While the scientists are catching the sharks to tag
234:03 them and take samples, we've gotta be really careful when
234:07 we're trying to capture this on film, because the shark's
234:09 attached with a hook to the boat effectively.
234:12 So if at any point that hook pops, that shark can swing by
234:15 its tail in almost this 180-degree motion.
234:20 And if we're in the way, we could get caught in the
234:22 shark's jaws or also between the shark and the boat.
234:27 MIKE: Okay. Got it. 252.
234:29 SARA: Awesome.
234:31 MIKE: So that's eight feet.
234:33 SARA: What we got here is an eight-foot lemon shark.
234:35 Caudal vein's a little deep 'cause it is a bigger shark.
234:38 And so Mike right now is drawing blood.
234:40 And once he's drawn the blood, he's gonna give that vial over
234:42 to me so that way, I can break it down to the three
234:45 components we wanna analyze.
234:47 NARRATOR: The caudal vein is the largest in the tail of a shark.
234:53 MIKE: Heads up. Heads up. Let it go.
234:58 Always assume they're gonna do the most dangerous possible
235:00 thing and you will not be disappointed and you'll be safe.
235:03 SARA: Got it? MIKE: Yup.
235:06 All we're doing now is getting some blood from
235:08 that caudal vein here.
235:10 There we go.
235:12 Good job.
235:13 That'll do the trick.
235:14 Okay, Sara.
235:15 SARA: Are you gonna stay by the head?
235:16 MIKE: I'll come to the head. SARA: Yeah.
235:18 MIKE: There we go.
235:19 SARA: Trade. MIKE: Okay.
235:20 SARA: Got it? MIKE: Yup.
235:22 SARA: So what I got here is the blood that Mike just drew
235:24 from the lemon shark.
235:25 What I'm gonna do is, first, put it in this vial, which
235:27 will make it easier for me to access with a pipette.
235:29 When we're taking blood from these lemon sharks, we are
235:32 able to then do a chemical analysis that helps us
235:35 determine whether or not the food is coming from just the
235:38 natural fish in the area or if it's coming from
235:40 a fisherman's chum bag.
235:43 NARRATOR: With sample in hand, the shark's released.
235:47 MIKE: Okay.
235:48 Now, we're gonna get this hook out and we're gonna let her go.
235:51 SARA: Got it.
235:52 MIKE: Duncan, you ready for it?
235:55 DUNCAN: I've been in the water for lots of shark releases,
235:57 and you never quite know how the shark is gonna react.
236:00 MIKE: Okay. I'm on.
236:01 Don't get anywhere near that mouth.
236:03 SARA: Perfect.
236:04 NARRATOR: This one decided to leave its mark.
236:08 MIKE: Oh, no! Look out! Look out! Look out! No!
236:15 DUNCAN: On the release, the shark was a little bit grumpy.
236:21 You know, it had been measured.
236:22 You know, had, had its blood taken.
236:25 You know, it's just like humans going to the doctor's.
236:28 We don't really like it but it has to get done.
236:30 It turned around and went straight for the engine.
236:33 It just took a big bite out of the side of the boat.
236:35 MIKE: Oh, no!
236:38 We're good.
236:39 There we go.
236:40 A little spree.
236:42 Nice job. Nicely done.
236:44 DUNCAN: Wow.
236:46 Just look at the damage that shark caused on, on the side
236:48 of the boat here.
236:50 It just shows how strong the bite force of these
236:51 lemon sharks are.
236:53 It's actually ripped part of the gel coat off with a couple
236:56 of chunks out of the boat and actually shredded the rubber
236:59 of the rub rail.
237:01 Wow.
237:03 It really proves that, you know, if these sharks really
237:05 wanted to mess us up when we're in the water,
237:07 we wouldn't stand a chance.
237:10 NARRATOR: Sharks circling boats and biting hulls while
237:13 snatching chum bags makes perfect sense.
237:17 But what about sharks biting boat engines?
237:20 MAN: Oh, my God!
237:22 MAN: Ah! MAN: (bleep).
237:29 NARRATOR: In the sea battle between sharks and boats.
237:32 MAN: Ah! MAN: (bleep).
237:36 NARRATOR: The sharks appear to target one area.
237:41 ERIKA: Oh, God.
237:43 The shark was definitely most interested in the
237:45 motors more than anything.
237:47 It would come under the water and grab the bottom of the propellers.
237:50 MAN: No way.
237:52 ERIKA: You could hear a loud, a large thumping sound and
237:55 then a scrape as its teeth hit the, hit the
237:57 motors and props themselves.
237:59 I thought either we are going to lose an engine or
238:03 we're gonna have to paddle ourselves home.
238:06 Oh, God.
238:09 NARRATOR: This isn't a case of missing a chomp on a chum bag.
238:13 These sharks going out of their way to gnaw on the
238:17 metal engine and props.
238:20 MIKE: We saw that we could get these lemon sharks up to the
238:22 boat just from the sound of the engine, but there are
238:25 plenty of videos online of sharks biting engines, and
238:28 that's not about the sound.
238:29 There's a lot more going on,
238:31 especially the creation of electric fields.
238:35 And sharks have an incredible electroreception sense.
238:38 It's kind of their superpower.
238:40 NARRATOR: All living things create an electrical charge.
238:43 A human heart beat is regulated by electrical
238:46 charges that signal muscles to contract and release.
238:50 An EKG reads those charges.
238:54 Fish also create electrical signals, signals that sharks can detect.
239:00 SARA: These boat engines are sending out these electrical signals.
239:02 And sharks have what are called ampullae of Lorenzini,
239:05 which are these little tiny pores around their snout and
239:08 particularly around their mouth area.
239:10 These allow them to detect electrical signals in the water,
239:14 which is super helpful when you're trying to get
239:16 fish or any sort of animal that's moving in the water.
239:20 But it can also lead to confusion when you're around
239:22 man-made objects that also emit electrical signals.
239:26 NARRATOR: It's called electroreceptivity.
239:29 And some sharks, like the great white, are so adept at
239:32 it, they can perceive as little as one millionth of a volt
239:36 in the water.
239:38 That's a tiny fraction of what a common AA battery generates.
239:44 Sara has constructed a test to reveal how effectively sharks
239:48 can detect electrical charges,
239:50 like those created by a boat engine.
239:54 SARA: What we have here is we have two circuit boards.
239:56 Both of them are powered by batteries in the Pelican case
239:58 and they both emit a current of about 20 milliamps.
240:02 And once we close the Pelican cases, we actually have these
240:04 switches on the outside to help us easily turn it off or
240:07 on and do any alterations we need.
240:09 What we're gonna do is we're gonna place both of these
240:12 circuits in the water, but one's gonna be on and the
240:14 other one's gonna be off.
240:16 This will enable us to observe the sharks and see how they
240:19 react and how they respond to the circuit that's emitting an
240:22 electrical field compared to the one that's not
240:24 emitting an electrical field.
240:27 NARRATOR: Sara's test should capture a shark's interest.
240:34 One last check.
240:36 MIKE: The one with the arm up has its power is on, right?
240:38 SARA: Yeah.
240:40 So once they're both in the water, I'm just gonna swim
240:41 over and I'm gonna put that arm down, so that way
240:43 it's on and running.
240:45 MIKE: Okay.
240:46 But otherwise you got them exactly identical?
240:48 The only difference is this one's got current going through it?
240:49 SARA: Absolutely.
240:51 And the one that is on, I actually already covered the
240:52 light bulb up, so we know that light is not gonna play
240:54 a factor in the shark's behavior.
240:56 MIKE: Awesome.
240:57 So, yeah, this will be a good test to see if they're
240:58 cueing in on electric fields rather than something
241:01 floating in the water.
241:02 SARA: For sure.
241:03 And then we're just gonna tie them off the side of the boat,
241:05 20 feet of line each, and see what happens.
241:10 MIKE: My expectation is we're gonna have a good number
241:13 of lemon sharks.
241:14 This is where they hang out.
241:16 But we might see bull sharks, and it is Florida,
241:18 so you never know what might show up.
241:22 NARRATOR: The moment they splash in, they're vulnerable
241:27 to the sharks.
241:32 A diver's vision is limited by the mask.
241:39 Lugging a bulky air tank means fleeing to escape
241:42 is out of the question.
241:45 SARA: You have to always assume that there is the
241:48 potential for an aggressive encounter,
241:50 especially when you're diving with sharks.
241:52 And that's why it's really important to kind of keep your
241:54 head on a swivel, be aware of your surroundings.
241:56 It's better to assume the worst and be prepared for it
242:00 than to be taken off guard.
242:21 NARRATOR: Company arrives.
242:45 NARRATOR: The two testers are out.
242:47 They're about 10 feet apart.
244:13 NARRATOR: The waterproof battery sending out an
244:14 electrical field draws a lot of attention.
244:19 The charges from the battery appear to mimic what a shark's
244:22 prey creates or a boat engine emits.
244:27 It would explain why many viral videos show sharks
244:30 attacking boat propellers.
244:32 JEFF: Ah!
245:05 MIKE: It was pretty incredible to see that from underwater.
245:07 And you could see the sharks knew that both of those boards
245:11 were out there and they checked out both of them,
245:13 but they spent almost all their time by the electrified one.
245:16 SARA: That's when they would get close.
245:17 They would bump it.
245:19 Sometimes not so gently.
245:20 Yeah, I mean, we can even see it right now.
245:22 They're still swimming past it.
245:24 They're still checking it out.
245:25 And what was really neat was also seeing the different
245:27 type of behaviors.
245:29 MIKE: That was incredible.
245:30 And if you think about how that relates to boat engines,
245:32 yeah, it probably shows that it is that electric field that
245:35 they're zeroing in on when they bite the motor.
245:37 SARA: Yeah.
245:39 And then let alone if there's any other stimuli going on,
245:40 such as someone fishing off of the boat, that's further
245:42 attracting the shark and getting them into that
245:44 foraging mindset.
245:46 MIKE: Yeah, well, I would say that that was a successful test.
245:50 NARRATOR: Science reveals why sharks attack boat engines,
245:54 but what about plastic kayaks and canoes?
245:59 Many of the most frightening viral videos
246:02 show sharks attacking kayakers and canoeists.
246:06 BEN: Yeah, do that.
246:07 CHRIS: Holy God! BEN: Oh, my God!
246:09 CHRIS: Holy (bleep)!
246:11 Oh.
246:12 BEN: Watch out!
246:14 CHRIS: Whew!
246:15 NARRATOR: Matt Rosenquist, Ben Sasse, and Chris Ester
246:18 are avid fishermen.
246:20 They prefer to head out under their own power.
246:23 CHRIS: I prefer canoes 'cause of the serenity.
246:25 You know, it's peaceful.
246:26 It's not noisy with the boat motors.
246:29 NARRATOR: The three friends were about three miles off
246:31 shore, fishing in the Florida Keys.
246:34 There were no engines to attract a shark when...
246:37 BEN: Oh. Watch out!
246:40 CHRIS: Oh, my God!
246:41 MATT: He attacked us. He literally attacked us.
246:45 BEN: When it first started coming up towards the boat,
246:48 Matt would say, "Oh, I think it's a nurse shark."
246:50 And then all of a sudden, I see these massive jaws.
246:54 MATT: Do you see that?
246:56 It came straight at the boat.
246:57 Hit it with all its force. And it was not happy.
247:00 BEN: Watch out!
247:02 MATT: That was a moment that if we had not had Chris's
247:05 canoe there, it could have been really, really bad.
247:08 CHRIS: Holy (bleep)!
247:09 MATT: I think Ben even fell into Chris's canoe.
247:12 CHRIS: Oh.
247:15 MATT: That was the confirmation that we were in
247:16 for the fight of our life.
247:17 BEN: Wait! Bull! Oh, my gosh!
247:19 NARRATOR: A bull shark came in charging, just like its namesake.
247:24 CHRIS: I remember the feeling of being kind of tossed,
247:26 and we're just hanging on for dear life.
247:28 Oh!
247:31 NARRATOR: Bull sharks have very high testosterone,
247:35 more than a male African Elephant in heat.
247:38 And this one was proving it.
247:40 MIKE: When you're a bull shark with that stocky build, you're
247:42 one of the few sharks in the ocean that'll eat prey about
247:45 your own body size instead of much smaller than you,
247:48 you know, that's a recipe for boat versus shark run-ins.
247:53 CHRIS: It was intentional.
247:54 It wasn't a single like, "Get away from me."
247:56 It was over and over.
247:58 Oh!
248:00 It would attack and then it would turn back around and attack.
248:02 BEN: Watch out!
248:04 I didn't realize it but my butt went in the water for a second.
248:08 SARA: It's really easy to just sit back and enjoy a shark if
248:10 you're on a 20-foot vessel.
248:12 But if you're on a small canoe or a kayak, that can be a
248:16 little more concerning.
248:17 There's very little separating you from the water,
248:20 and it wouldn't take much to knock you over.
248:23 CHRIS: My God!
248:24 Oh!
248:26 BEN: It was like one part excitement and then this
248:29 other part, like surreal.
248:33 Is this really happening?
248:35 MIKE: There are a few things that could attract
248:36 a shark to a kayak.
248:38 You know, one would be the silhouette.
248:40 You know, for a big shark, like a white shark,
248:42 that silhouette may mimic what its prey is.
248:46 For other species, the silhouette may be something
248:48 worth checking out 'cause maybe there's other prey
248:50 around some floating object.
248:52 But then there are other sensory inputs too.
248:54 You know, the paddle dipping in, if a shark's nearby,
248:56 might be worth investigating.
248:58 Not necessarily, you know, flying in to attack but just,
249:01 "Hey, something novel in the environment.
249:03 I'll check that out."
249:05 NARRATOR: A kayak, lemon sharks, and a fishing pole
249:08 allow Mike to reveal why a shark might attack a kayak.
249:13 SARA: All right, Mike, you head on out with the kayak and
249:15 I'll keep an eye on you from the sky with the drone, okay?
249:18 MIKE: Sounds good.
249:19 SARA: All right.
249:20 All right. We're sending the drone up.
249:23 Right now, I'm just keeping an eye on Mike on the kayak
249:25 using the drone.
249:27 Getting a bird's eye view of things.
249:28 Seeing where the sharks are, where Mike is.
249:30 NARRATOR: Duncan is below for the underwater vantage point.
249:36 As if on cue, the sharks arrive.
249:41 A bit of a homebody in the shark world, lemons prefer
249:44 a home range rather than long migrations.
249:48 MIKE: So I'm out here kayaking.
249:49 We might see one or two lemon sharks, but I'm not putting a
249:52 lot of stimulus into the water.
249:54 Just a little bit of sound when I put the paddles in
249:56 and there's the silhouette.
249:58 But this silhouette doesn't match the prey of the sharks
250:01 we see around here.
250:03 Let me know if any sharks are coming.
250:09 SARA: There's one or two who keep swimming past Mike on the kayak.
250:17 You got one coming under your bow, just swimming past you
250:19 right now, Mike.
250:20 MIKE: Yup.
250:23 NARRATOR: Mike wants to avoid what happened to Ben Chancey
250:25 off Stuart, Florida.
250:27 Ben's an experienced paddler who's fished from kayaks for
250:30 18 years.
250:32 CHANCEY: He's right underneath of me.
250:34 Oh, my God.
250:35 Whenever a fish over 300 pounds decides to go crazy and
250:38 you're in a kayak, there's nothing you can do.
250:47 We're off the East Coast of Florida and we're trying to
250:49 catch the biggest fish that we've ever caught out of a kayak.
250:53 We get out there and we catch a bonito for bait and then we
250:55 drop that bonito down and something huge grabs it.
251:01 Lo and behold, I realized it's a giant bull shark
251:04 and I'm like, "Wow. We've got a bull shark on.
251:06 This is crazy."
251:09 It's spinning me around.
251:10 It's almost like being on a rollercoaster ride and
251:11 I'm getting pulled all around.
251:13 And I'm like, "I don't, I don't know what's going on."
251:14 It pulled so hard, it felt like it's gonna flip me right
251:17 over out of the kayak and I couldn't hold on to the rod anymore.
251:23 There was a moment where I was paused and I'm like,
251:25 "Oh, I got flipped over."
251:27 I didn't automatically go, "I better get for the boat
251:29 'cause I could get eaten."
251:31 Once I realized that fish was still tied off to my kayak,
251:33 I'm like, "I gotta get to the boat."
251:35 So I swam as fast as I could.
251:37 I did my best Michael Phelps impression.
251:40 It might not look like Michael Phelps but I felt like
251:42 I swam as fast as him to get back to the boat.
251:45 MAN: He's still on.
251:50 MIKE: You might think that these interactions are
251:52 unprovoked, but when you look at the kayaks and canoes,
251:55 there's one common thread most of the times, fishing.
251:58 BEN: Watch out!
252:02 CHANCEY: Oh!
252:05 MIKE: What we saw already is shark's not super interested
252:07 in the kayak, but we're gonna ramp it up a little and test
252:11 the conditions we see in a lot of those videos by adding some bait.
252:15 Now, we don't have a hook here.
252:16 We'll tie the fish on and I'm gonna throw it out there.
252:19 Let's see what happens.
252:23 SARA: Once Mike casts that line and the fish hits the water,
252:25 I'm expecting the sharks to immediately be
252:28 drawn to that sound.
252:29 And as he reels that in, follow it because there is
252:31 fish blood.
252:32 That's just a free meal on the end of the line for the sharks.
252:35 MIKE: Okay. Ready?
252:38 SARA: You're good.
252:41 MIKE: Bait's out.
252:44 SARA: We're gonna see a lot faster behavior.
252:45 They're gonna be really interested in the kayak and
252:48 what's the end of that line.
252:49 MIKE: Sara, the bait's out but I can't see anything.
252:52 Let me know if I need to reel.
252:53 SARA: Right now, one is passing right underneath you, Mike.
252:56 No. She's coming.
252:58 MIKE: Okay. This one's coming fast.
253:00 SARA: Pull in that fish, Mike.
253:02 MIKE: Ah!
253:05 Woo! Perfect.
253:07 So you can see how fast that shark is swimming toward the boat.
253:10 That's exactly the kind of situation where you could get
253:12 a shark running into a kayak, not 'cause it wants to bite
253:15 the kayak but 'cause it's interested in the fish
253:17 on the end of the line.
253:19 Yeah.
253:20 That one's nice and close.
253:23 NARRATOR: The science behind shark behavior reveals the
253:25 truth behind most viral videos.
253:28 But there are some videos where biology or chemistry
253:32 aren't the cause of boat/shark encounters.
253:35 MAN: No way.
253:36 NARRATOR: Sometimes it's personality.
253:38 JEFF: Ah!
253:40 NARRATOR: Not the boaters but the sharks.
253:45 Carl Torresson was fishing just off-shore of Jupiter, Florida
253:48 when he came in contact with one ornery bull shark.
253:58 CARL: We started the day offshore fishing.
254:00 We got the word that there was a, a good cobia bite
254:02 going on the beach.
254:03 We were about this far offshore.
254:05 We found, we came in here, my dad told me,
254:07 "The shark's attacking the boat. What's going on?"
254:09 Every time he grabbed the boat, the boat would stop.
254:12 Then he came back around and when he hit the side of the
254:13 boat, it was like a boom.
254:17 I thought we hit a reef.
254:21 SARA: Bull sharks have a reputation for being a bit
254:23 more aggressive, a bit bolder.
254:26 And that's not necessarily untrue.
254:28 CARL: This wasn't about the electricity in the water.
254:31 This shark was just an angry, angry shark and
254:33 we were interrupting his day.
254:35 He attacked the boat and he kept attacking the boat with,
254:38 with intent to kill the boat, kill whatever he was biting.
254:42 The power that he was grabbing the boat with is unbelievable.
254:47 MIKE: That video of the big bull shark attacking a fishing
254:50 boat is something I'm not used to seeing at all.
254:54 CARL: After he hit, ate the motor and was biting on the
254:57 motor, he actually came by and hit the side of the boat.
254:59 Boom.
255:00 You were literally moving.
255:02 It was like a Universal Studios' ride but it was so surreal
255:04 that it was a shark doing it and that a shark was that powerful.
255:10 MIKE: In our studies of bull sharks, we found that
255:12 different individuals have different personalities,
255:15 if you wanna call them that.
255:16 Some are bold. Some are shy.
255:18 You know, not every individual is gonna react the same in
255:21 every situation.
255:22 You know, maybe these guys came across a big shark
255:26 that was willing to attack and
255:31 just decided to go after the boat.
255:33 I mean, it's hard to tell what the motivation of that shark
255:35 was but it certainly was going after the boat.
255:42 NARRATOR: To observe how bull sharks react to anything new
255:44 entering their space,
255:46 Sara and Mike head to a known bull hangout.
255:51 SARA: I've seen that video.
255:52 That bull shark was behaving really aggressively.
255:54 But that sort of behavior is really rare,
255:56 especially when you're diving.
255:58 MIKE: Yeah.
255:59 You know, these are big predators and they can get aggressive.
256:03 But usually there's a reason for it.
256:05 So we're down there.
256:06 I'm not expecting to see anything like that, but still
256:08 we'll stay shoulder to shoulder, keep our eyes on things.
256:11 SARA: Uh-hmm.
256:12 DUNCAN: I think if there's anything the area, we're
256:14 drifting along the edge there, they'll come up and
256:16 investigate us.
256:18 NARRATOR: Duncan will film the encounter.
256:20 DUNCAN: Whenever you jump in the water with bull sharks,
256:21 you've gotta have your wits about you.
256:25 They're incredibly unpredictable shark that's
256:28 always testing you, coming from all different angles.
256:31 You pretty much have to have your head on a swivel.
256:36 NARRATOR: In addition to having very high testosterone,
256:40 bull sharks are thought to be more dangerous to humans
256:42 than great whites.
256:48 Sara and Mike need to be aware at all times of how many
256:52 sharks are around and where they are.
257:39 NARRATOR: They ease into the bull shark's space.
257:42 As observed, bull sharks will ram a boat and
257:45 are known to attack humans.
258:10 NARRATOR: Surrounded by bull sharks, shark researchers,
258:13 Dr. Mike Heithaus and Sara Casareto, gauge the
258:16 sharks' behavior to determine if they're in danger.
259:07 MIKE: That was incredible.
259:08 And the amazing thing to me is bull sharks have such a bad
259:11 reputation for being aggressive and, I mean, there
259:14 are videos of them bodyslamming boats,
259:16 but those sharks were just so calm.
259:19 SARA: They were just cruising.
259:21 I mean, I did not at any point feel worried.
259:25 MIKE: There is some personality in there too.
259:27 SARA: Yup.
259:28 MIKE: You could see some of the individuals would come in
259:29 really close, but give plenty of space.
259:32 And others were just hanging out really far in the distance.
259:34 SARA: Yeah.
259:36 They were enjoying the dive just as much as we were, it seemed.
259:37 MIKE: It really shows that, you know, these animals are
259:39 not, as a rule, super aggressive.
259:42 These are not animals that you'd expect to be coming in
259:44 and just attacking a boat for no reason at all.
259:49 NARRATOR: While the viral videos of shark/boat
259:51 encounters are intense.
259:53 BEN: Watch out!
259:54 NARRATOR: No one on a boat or a kayak was bitten.
259:57 That changed off the coast of Tasmania in Australia.
260:05 DARYL: It's a really unique little area.
260:08 Quiet area.
260:09 Not too much drama happens here in Stanley.
260:12 It's a historic town, and there's around 700 people that
260:15 live here in Stanley full-time.
260:17 It's always been a fishing village.
260:19 NARRATOR: Winter in Tasmania.
260:21 The water is cold and few venture in for a swim.
260:25 A shark attack seems like an impossibility.
260:29 TODD: The incident at Stanley was an extremely rare occurrence.
260:32 I've never seen a shark or heard of a shark doing that before.
260:36 DARYL: I know that sharks have been sighted off Stanley,
260:39 but I've never heard of sharks attacking a boat or people at all.
260:46 NARRATOR: Even so, a warning of a large shark in the area
260:49 was issued when John Arnott and his son, Lucas, age 10,
260:53 were fishing off the coast.
260:56 Without warning, a shark grabbed the boy off the boat
261:00 and dragged him into the water.
261:04 Within seconds, the father dove in to save his son from
261:07 the jaws of the attacker.
261:10 The shark, thought to be a great white,
261:12 let him go in moments.
261:15 Many claimed the boy's life jacket and heroic father
261:19 saved his life.
261:21 DARYL: We hear of surfers being taken by great whites,
261:24 but we've never heard of that happening anywhere in Australia.
261:31 NARRATOR: The child was released from the hospital
261:33 after being treated for wounds on his chest,
261:35 shoulder, and head.
261:37 DARYL: Probably, everybody was a bit numb for a start because
261:41 it was just something that you just never
261:43 hear about in Australia.
261:46 TODD: I've only had around sort of one great white
261:48 touch the boat.
261:49 It's more curiosity than anything.
261:51 And it's very, very unlikely that you'll get grabbed by
261:53 a shark off a boat.
261:54 Well, I mean, it can happen but it's very unlikely.
261:58 NARRATOR: It seemed a line was crossed between shark and human.
262:01 Being on a boat didn't mean you were safe.
262:04 MIKE: The reports of that encounter in Tasmania are like
262:08 nothing I have ever heard before.
262:10 A boy was dragged out of a boat while he was fishing.
262:14 But we just don't know enough about what happened.
262:18 SARA: It's really hard to know what was going on in the
262:20 shark's head at that time.
262:22 They were fishing.
262:23 There was that stimuli.
262:24 But it's just such a weird occurrence.
262:27 It's, I've never heard of something like that happening
262:29 before with any type of shark.
262:32 NARRATOR: Encounters between sharks and boats will only increase.
262:36 Fortunately, the truth is these aren't attacks.
262:39 JEFF: Ah!
262:42 MAN: No way.
262:46 NARRATOR: Just encounters with an animal in its domain.
262:51 DUNCAN: With shark populations all over the world declining,
262:53 I feel like if, you're lucky enough to have a
262:55 shark attack your boat.
262:57 You should just lay back and enjoy the moment and
262:59 look at the animal.
263:01 SARA: You are seeing one of the most well-designed
263:04 predators on the planet doing its thing.
263:08 And if you see anything super cool, let me know.
263:12 NARRATOR: The results from the blood sample from the
263:13 lemon shark are in.
263:15 It provides a rare insight into shark and boat encounters.
263:19 MIKE: When you look at the samples and you look at what
263:21 these sharks are doing,
263:23 they're not getting a lot of food.
263:24 You know, we're not really seeing indications that it's
263:26 probably completely changing their feeding behavior.
263:29 Most likely what's going on is that these sharks are in the
263:32 area and, hey, maybe get a little bit of free food here.
263:35 Why not take a few tail beats and go over there and
263:38 check it out?
263:41 Of course, there's more work to do, but the initial
263:43 indications are certainly that this is not having a major
263:45 negative effect on the sharks.
263:47 Whoa!
263:49 It pulled it out of my hands.
263:51 Our takeaway from looking at the behavior of these sharks
263:53 and all the videos is that these sharks are not really
263:57 trying to attack boats but they're responding to stimuli
264:01 like bait and electrical charges,
264:05 and you're not gonna need a bigger boat.
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