BBC_Nature_Whale Shark
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00:00A giant roams the world's oceans.
00:28At more than 12 meters long, the whale shark is the largest fish in the sea.
00:42Yet for all its size, it remains a total mystery to science.
00:54For most of the year, they travel the oceans undetected.
01:01Then off tropical coasts and coral reefs, the whale sharks suddenly appear.
01:10Where they come from, nobody knows.
01:15But just as mysteriously as they arrive, the whale sharks soon disappear.
01:27Shark expert Dr. Mark Meakin is on a quest to find out where they go.
01:33He believes they're traveling huge distances, and could even be crossing oceans.
01:41Over the next year, Mark will attempt to track the whale shark's movements.
01:49If all goes to plan, he will unravel one of the ocean's great mysteries.
02:08Ningaloo Reef, Western Australia, where the Indian Ocean meets the harsh desert coast.
02:18Just 100 meters offshore lies one of the world's richest coral reefs, where an incredible event
02:26is about to take place.
02:34It's early April, and seven days after the full moon, a neap tide calms the great ocean swell.
02:49Underwater, the reef is stirring.
02:54Finally, the conditions are right for the coral to spawn.
03:02Over the next 24 hours, several tons of sperm and eggs will be released into the water.
03:19Overnight, the reef explodes into life.
03:29And soon, one of the most mysterious animals in the ocean appears.
03:46For a few brief months each year, hundreds of whale sharks come to cruise the Ningaloo coastline.
03:59They're the ocean's great wanderers.
04:03But outside these waters, almost nothing is known about their lives.
04:11The first time I swam with a whale shark was about 10 years ago now, out the front of Ningaloo Reef.
04:18Beautiful, calm day, jumped in the water, and out of the deep blue came this great big shape.
04:26You've got an animal that hasn't changed, basically, since the age of the dinosaurs.
04:32You're swimming with a dinosaur, and at the same time, it's just an absolutely beautiful animal.
04:41Now Mark Meakin is finding worrying evidence that whale sharks are on the decline.
04:49Over the last 10 years, the average size of sharks we've been seeing has been getting smaller.
04:55And it's alarming because it's a classic symptom of overfishing.
05:00If my kids want to swim with whale sharks, there are really two questions that we actually have to answer.
05:06The first of those is, where do they go after Ningaloo?
05:11The second one is, who are they interacting with?
05:15Those are the things we've got to find out.
05:21The next morning, Mark heads out on the first day of his tagging operation.
05:30They have just one week to deploy six satellite tags.
05:39They may be searching for the biggest fish in the ocean, but it's still a challenge to find them.
05:49Nor'west air, nor'west air, this is the Ossa Blue, do you receive, Tim?
05:53Go ahead, Ossa Blue, this is nor'west air.
05:57From the air, you can see the sharks much, much better than you can see them on the water.
06:01These things are brilliantly camouflaged, but in the air, they're silhouetted.
06:05The pilot can look down, spot the shark, and he can lead us straight to it.
06:10Now, the key thing is, the whale sharks have to show up and want to play.
06:17Yeah, Tim, we'll hang around Black Rock here, so if you get a shark, we'll have a good run to it, eh?
06:23Roger that.
06:28Stretching 260 kilometres across the west coast of Australia,
06:33Ningaloo is one of the largest fringing reef systems in the world.
06:38And at this time of year, it explodes into life.
06:45Every creature in the ocean is moving in to feed and breed,
06:49from the smallest to the largest.
06:52They've all come to exploit the reef's nutrient-rich waters.
07:05Orissa Blue, Orissa Blue, this is nor'west air, do you copy?
07:09Yeah, receiving. Tim, what have you got for us, eh?
07:12I've got a whale shark about half a mile off here, Orissa.
07:15Guys, guys, got a shark. Okay, and he's going north at about what speed, mate?
07:21The whale shark has been spotted at the surface,
07:23but it's an unpredictable animal and could disappear at any moment.
07:29How big was it, mate?
07:30It's a seven metre shark, but he's diving, so we need to get down there quick.
07:33Toe tag?
07:35Toe tag. Let's get it on.
07:41It's coming up in a wave now. You got it, you got it?
07:43We're all good to go. Gun loaded?
07:46Gun's loaded, safety's on.
07:48Where is it, sir? Can't see it, where is it?
07:50It's coming up in a wave.
07:51I've got it, yeah.
07:52Okay, guys, right up there, right up there. Go, go, go, Kerry, go.
08:01Keep going, keep going, you're heading straight at it.
08:20Every shark is photographed for their database.
08:23The tag is designed to drop off after a year.
08:27For the shark, it will be painless, but for Mark, it's a dangerous moment.
08:34An animal this large must be approached with extreme caution.
08:39A direct hit from its tail could cause serious injury.
08:53I'll pass you the gun there, Kerry. Careful, it's still loaded. It didn't go off.
09:03We got in the water, got up to it, got the tag on the animal, and the gun didn't go off.
09:14You know, occasionally these things happen. We're just going to have to work out what happened.
09:19What didn't go off?
09:25Beneath them, the conditions are perfect for whale sharks.
09:31As the current runs over the reef,
09:33it brings with it a cloud of minute sea life that turns the water cloudy.
09:40And soon, the ocean's filter feeders are drawn to the feast.
09:49Whale sharks are the largest of all sharks.
09:53Fully grown, they're twice the size of a great white.
09:58And with a mouth up to two meters wide, they could easily engulf a human.
10:15But these sharks are gentle giants, and unlike their fearsome relatives,
10:19they filter their food.
10:22Gulping thousands of liters of water every hour,
10:25they use their huge gills to sieve out small particles of life.
10:37OK, we've got a whale shark just off the bow.
10:40With the gun fixed, Mark is back in action.
11:10As Mark approaches, the whale shark turns its back in a defensive posture.
11:16Here, its skin grows up to 14 centimeters thick,
11:20thicker and tougher than any animal in the world.
11:40Breath-holding to 15 meters,
11:42Mark's first successful tag shows just how dangerous it can be.
11:48This animal's swimming towards you at about two knots.
11:50It's like a bus coming past,
11:52and you're trying to whack something on the side of the bus as it goes past.
11:56It's not a simple matter.
11:58The animal's big, it's got a lot of teeth,
12:00it's got a lot of teeth,
12:02it's got a lot of teeth,
12:04it's got a lot of teeth.
12:07As the afternoon progresses, more sharks are tagged,
12:11and the project gets off to a good start.
12:15Do you know what I was doing?
12:17What's coming in front of me?
12:21Let's see.
12:25OK, so here we go.
12:28What's coming in front of me?
12:30What's coming in front of me?
12:34What's coming in front of me?
12:37Do you know what I was doing today? I tagged three whale sharks today. Three! Three great
12:51big ones. It's my son, he's five years old and he's got a... well he loves whale sharks
12:59and I was hoping maybe we could get some names for some of the whale sharks we tagged today.
13:06You know, he came up with some names. Hamish and Jack, two of his school friends.
13:20As the moon rises over Ningaloo, it's time to input the day's data.
13:28Over the last ten years, the team has built up an impressive database of whale shark sightings.
13:35Each animal has a unique pattern of spots that allows Mark to identify and cross-reference
13:40every individual.
13:41OK, let's see if we've got any matches from today.
13:46The first shark to be analysed is a six-metre male he calls Hamish.
13:53The next two are smaller adolescent males named Jack and Sammy.
14:00Have they ever been seen in these waters before?
14:04The photo ID results show they're new to the database.
14:09But just like the other sharks at Ningaloo, they share one thing in common.
14:15The population here at Ningaloo, they're all young males. They're all juveniles really.
14:20Although they're quite large, five to six metres in size, they're still babies really.
14:26They haven't become mature.
14:30By the end of the week, a total of six whale sharks are tagged.
14:36Now every time Hamish and the others surface, a satellite deep in space will record their
14:41every move.
14:46But unlike a true whale, these sharks don't need to come up for air, and could spend several
14:51days deep underwater.
15:05With the tags on, Mark can now focus on another whale shark mystery.
15:11Beyond a few brief encounters at the surface, almost nothing is known about their day-to-day
15:16lives.
15:17We're going to try and attach this camera to the sharks, but it's much more than a camera.
15:22It's a mini laboratory, it's a dive computer.
15:26This has never been done successfully before, but if we get it right, it's going to tell
15:30us about what the animals are feeding on, how they get down there, and what they're
15:35actually doing on the bottom.
15:38We can't go down there, this can, and when it pops back up to the surface, we get that
15:42information back.
15:54The camera is attached by a time-sensitive fuse, and will release at 4am tomorrow morning.
16:05Riding on top of its back, the camera will capture a shark's eye view of Mingaloo Reef.
16:13Offering for the first time, a unique window into the whale shark's world.
16:20What secrets will it uncover?
16:33The next morning, the team head out early.
16:36We've got the lat-longs of the camera, it's come off the animal, it's floating in the
16:42ocean, we've got to go and get it.
16:45The coordinates will get them close, but from here on they must rely on a VHF receiver to
16:50pick up the camera's signal.
16:54With $40,000 of equipment floating in the open ocean, there's a lot riding on its safe
16:59return.
17:00One o'clock, straight ahead.
17:01Oh yeah, there it is, there it is.
17:02Got it.
17:03Keep coming, Terry.
17:04One o'clock, Terry.
17:05About four boat legs.
17:06Yeah, they're in the same position.
17:07Okay.
17:08Four boat legs.
17:09All right.
17:10Coming down this way.
17:11Woo-hoo!
17:12Well done, Randy.
17:13Thanks.
17:14Oop, he's got it.
17:15Yep.
17:16Woo-hoo!
17:17Hey, you caught a fish.
17:34A very expensive fish, look at that.
17:37Great, fantastic, we've got it back, we've got it back.
17:44Well, hopefully it's full of data.
17:47That's the next question. Did the camera work? Did the instruments work? That's the thing.
17:51If they did, it's fantastic. It's a huge amount of data in there. Something that no one's
17:56ever managed to get from whale sharks before.
18:03While the shark cam data is being analysed, information starts to come in from the other
18:07tagged sharks.
18:11Will they finally discover where Ningaloo's whale sharks are going?
18:18In the weeks that follow, Mark tracks their progress up and down the coastline as they
18:23continue to feed on Ningaloo's rich currents.
18:32By mid-May, one of the sharks, the six-metre male called Hamish, breaks away from the group.
18:40Moving offshore, he leaves the security of the Ningaloo Marine Park, travelling 800 kilometres
18:45into the Indian Ocean.
18:51It's an exciting development. It confirms Mark's suspicions that Ningaloo's whale sharks
18:56are not only leaving Australia, but travelling huge distances.
19:08But it's here, entering the busy shipping lanes of Asia, that Hamish is most vulnerable.
19:22Every year, hundreds of whale sharks are killed by boat strikes, fishing and even pollution.
19:30It's having a devastating effect on the Ningaloo population.
19:38Ten years ago, whale sharks averaged seven metres in size. Today, the whale sharks we
19:44see out there are three to four metres in size. That's a drop of two metres. That's
19:48big. There's also been a worrying decline in abundance. Now those are classic signs
19:53of a population in trouble. It makes it all the more critical that we find out where these
19:59sharks are going to. You have to know where they're going and who you have to talk to
20:04if you're going to do anything about the problem.
20:09Protecting an animal that moves through international waters isn't easy. But thankfully, Hamish's
20:16journey doesn't end there. Whilst the other sharks stay around Ningaloo, Hamish continues
20:22west at a rate of 30 kilometres a day. But before more satellite data comes in, the shark
20:34cam starts yielding some interesting results.
20:39We put the shark cam on the sharks to really, for the first time, get a view of what the
20:44shark is actually doing down on the bottom at Ningaloo. And it's an amazing bit of footage
20:50we've recovered. On the surface we can see the shark actually gulping and feeding at
20:55things. But there are plenty of strange behaviours in here as well that I can't explain. There's
21:02some interesting behaviour where the shark is literally standing on its tail and sinking
21:05down from the surface. What it's doing then I have no idea.
21:14And more surprises are being revealed by the 3D dive profile.
21:20These animals are a lot like marine mammals. They go down and come back up again. Why?
21:25Well one, it's a search for food. The water's in layers. Smells travel really well through
21:30those layers. And if you're a shark, you go down, you go up, you pass through all those
21:35layers, you get a good sample of what's around to feed on. The other thing is that even though
21:40these are big animals, the water down at the bottom is colder than it is at the top. So
21:45it may well be that when a shark spends a lot of time at the bottom, it actually has
21:49to come back up to the surface to reheat. But we need a lot more footage like this to
21:54really understand the reasons behind that diving behaviour.
22:05It's two months since the tags were deployed and Hamish has travelled a thousand kilometres.
22:13Where he is heading, nobody knows. Mark has a hunch that Hamish could be following seasonal
22:20food pulses around the Indian Ocean.
22:24We know that these animals turn up at Ningaloo for these mass feeding events. There are other
22:31places around the world's oceans where this happens as well.
22:36In the Indian Ocean, they also turn up periodically to feed off Christmas Island, India, Kenya,
22:43Mozambique and the Seychelles.
22:48The real question is, are they the same animals that are actually participating in all these
22:52events? Are they travelling between them?
22:56The DNA evidence shows they are all closely related and could be part of one large interbreeding
23:01population.
23:07So could Hamish be travelling from Australia to Africa?
23:17As he continues west, now almost a thousand kilometres from Ningaloo, some disappointing
23:23news comes in.
23:26The tags are off the animals, they're floating. How they came off, I don't know. It's just
23:31one of those things. We have to expect a high failure rate for tags, so we just have to
23:37get more out there, get more on the sharks. I think it's the only way forward.
23:51Following his hunch, Mark flies 5,000 kilometres across the Indian Ocean to the tropical islands
23:57of the Seychelles for a working holiday with his family and the next leg of the study.
24:05To meet them is long-time collaborator David Roat, who runs the largest whale shark monitoring
24:10programme in the world.
24:11How are you?
24:12How are you two?
24:13So you've been getting good sharks, David?
24:14Yeah, sharks arrived about a day or two ago. We're getting reasonable numbers at the moment,
24:15about three or four each day.
24:16It's taken 18 hours to get here from Australia. And now Mark and David have just one week
24:24to find out if the whale sharks are making a similar journey.
24:34Basically the boats are going out every day, so yeah, they're ready to roll.
24:47Perched on the edge of the African continent, the granite islands of the Seychelles rise
24:52out of the Indian Ocean. It's the start of the whale shark season, and for the next
25:00three months, seasonal upwellings of nutrient-rich waters will attract whale sharks to these
25:07shores.
25:08Real time, real time. I'm gliding up up here. I've sighted a shark. It's just south.
25:16During this period, every encounter is photographed, measured and recorded.
25:29And what's so special about this research is that almost all the data is collected by
25:34tourists.
25:35Thank you for coming along, because it's only with your assistance and support that we can
25:41actually run this programme.
25:44It's all part of David Rowat's plan to make the whale sharks more valuable to the island.
25:51And by offering hundreds of tourists the chance to swim with them, it means that David can
25:55run his research on an epic scale.
26:02It's this data that could tell Mark if Ningaloo sharks are visiting the Seychelles.
26:08That long line there, it's not the same shark.
26:11Both David and I have very large photo identification libraries of whale sharks, me in Ningaloo
26:16and David in the Seychelles. And what we've been doing is using a computer programme to
26:21try and match those photographs.
26:24So we've done the fingerprint. We've got our three points in.
26:29If Hamish and the other Ningaloo sharks really are crossing the Indian Ocean, they would
26:33expect to find some matches.
26:39But with over a thousand images to compare, it will be another month before they'll know
26:43the result.
26:47In the meantime, Mark and David have more tags to deploy.
27:03And in real time, if you come right 45 degrees and 500 metres from you, 45 degrees, 500 metres.
27:34Every year, more than 200 sharks visit these islands. But when the food runs out, almost
27:42all of them disappear.
27:47By tagging more whale sharks, Mark and David hope to find out where they're going.
27:54Could they be heading back to Australia and the rich waters of Ningaloo?
28:10After a successful start, it's time for Mark to head out for some fun with his six-year-old
28:15son Sammy.
28:16We've promised him he can go swimming with a whale shark.
28:24I think I'm more delighted than he is, actually. I mean, it's been such a fondly held dream
28:29of mine for so long that I finally did it, you know.
28:37It really was a contrast between the two of them. I mean, there's Sammy. He's just over
28:54a metre tall, and that shark is five or six times his size. And he's not afraid of it
29:01at all. He's perfectly happy to paddle along with the shark.
29:20Missing most of its dorsal fin, this shark is typical of the population in the Seychelles,
29:26where some 30 per cent carry the scars of boat strikes.
29:34It's a sobering reminder of just how vulnerable these sharks are.
29:40It was important for me to have Sammy swim with a whale shark, you know, and share the
29:45joy I get out of them with my kids. And it's important to do it now, too, because who knows,
29:53when he's my age, they may not be around.
30:02As the week progresses, the team collect data on ten more whale sharks. And as Mark's trip
30:09draws to a close, they attach a second satellite tag to a four-metre male named Joe.
30:23Soon data comes in showing him moving north along the main island.
30:29But as Mark returns home, the airwaves go silent.
30:35And as weeks turn into months, it becomes all too apparent that the satellite has lost
30:40contact with the sharks.
30:45You know, pretty disappointed that yet another tag design has failed. But look, there are
30:51some real positives that came out of the Seychelles. One of those was the photo ID
30:57study. We found no matches between the Seychelles and Ningaloo. That's really significant, because
31:03it tells us that the animals probably aren't travelling between Ningaloo and the Seychelles
31:07or vice versa. And what I think it means is that we have to look closer to home for some
31:12of the answers about where these animals are going.
31:18If Ningaloo's whale sharks aren't crossing the Indian Ocean, then where are they heading?
31:29Mark re-examines the data from Hamish, the adolescent male that lost his tag mid-ocean.
31:38Sixteen hundred kilometres from Ningaloo lies the tiny Australian outpost of Christmas
31:43Island, where there are reports of whale sharks gathering.
31:56It's a tiny little green speck out in the middle of the Indian Ocean, but to whale sharks
32:01they see it from a different perspective. It's a giant mountain arising out of the sea
32:05floor, and the whale sharks turn up there predictably every year.
32:11Arriving on the tail end of a storm, Mark has just two weeks to find some answers.
32:19But his first lead doesn't point to the ocean. Instead it takes him inland, to the lush tropical
32:25forests that cover Christmas Island.
32:30Here, beneath a pristine canopy, one of the greatest events of the natural world is underway.
32:40Crabs, crabs on the road.
33:02It's a red land crab. It's land crab breeding season and these guys are all moving down
33:08out of the forest, down to the beach. Each one of these crabs is spawning about 100,000
33:13eggs. And you've got to figure that with about 15 million females on the island, we're talking
33:18about a billion eggs being released into the ocean. Now, we don't know if the whale sharks
33:24are actually eating them or not, but you have to figure that it would make sense.
33:29The crabs only spawn on one night of the year. Is it just coincidence that the whale sharks
33:35arrive at the same time?
33:50It's now a month since they left their forest homes and their arduous migration is almost over.
33:57Now heavily laden with eggs, the females navigate the final stretch to the ocean.
34:15In a few hours time, a hundred million new lives will be launched into the water.
34:26At 4am, on the turn of a high tide, the action begins. Like their marine ancestors, the land
34:33crabs are still tied to the ocean, and their eggs can only hatch when they reach the water.
34:39They're still alive.
34:42They're still alive.
34:45They're still alive.
34:48They're still alive.
34:51They're still alive.
34:53They're still alive.
34:57Now, that, that mick is just, that is solid, crab. Look at it.
35:03There they go, they're flapping. Look at that, there's the jig as they release the eggs.
35:10As the eggs hit the water, they hatch immediately to these tiny little crab larvae,
35:14they'll swim around for about 27 days out in the water and then come back in a stage called
35:19in a stage called a megalopi that looks just like a baby juvenile crab climb up the cliffs and
35:25Head back into the forest
35:27Look at the water. It's it's brown with eggs. You've got a figure that
35:32This is a great reason for the whale sharks to come to Christmas Island
35:40No one has ever witnessed sharks feeding on red crab larvae, it's just a theory, but if Mark can prove it it will be a first
35:49But
35:55The next day gets off to a slow start
36:00We're very keen to get out and see if we can find some whale sharks
36:04One problem is though that our plane our aerial support is out there on a supply ship the weather's been so bad
36:11They've been unable to bring the boat in against the warfare so without that plane
36:15It means we're just gonna have to get out there and maybe do an exploratory dive and just see what we can see
36:24With no indication of when the boat might come in
36:27Mark's best chance of finding a whale shark is to start surveying the island's 80 kilometers of coastline
36:45Surrounded by a narrow ledge of tropical reef the seabed quickly drops away to the abyssal depths of the Java Trench
36:55Four kilometers below the surface it's one of the deepest points in the Indian Ocean
37:02And it's along these walls that the whale sharks are reported to cruise
37:06As you went over the edge of the drop-off you leaned forward and it was like you were flying a plane into the depths
37:18An absolutely fantastic feeling
37:23It truly is the edge of the unknown
37:25You're on the edge of the unknown
37:28You're on the edge of the unknown
37:30You're on the edge of the unknown
37:33It truly is the edge of the unknown
37:36You feel like you're you're clinging to the last vestiges of of the land
37:41And somewhere out there are these giant creatures cruising up and down
37:49But until they can get up in the air the sharks remain as elusive as ever
38:03Then on the fifth day the container ship finally comes in
38:08And with just one week to go mark's study can at last take off
38:17The team's first task is to locate the whale sharks and establish where they're congregating
38:23What a great morning for flying. Yeah, it's awesome, isn't it? Beautiful. You get a great view from up here, don't you?
38:30Yeah
38:32It's the first time a whale shark survey has ever been conducted on christmas island mark has no idea what he's going to find
38:41That was that's deep that's deep. Let's just swing around i'm pretty yeah, that's a shark. Okay. Look at that. That's a big tadpole
38:48Check out that look at that. They look just like big tadpoles. I mean a great big fat head
38:54And the skinny tail at the top at the back. It's funny, isn't it? Oh, we lost him
38:58as planned
39:04Well, we saw two whale sharks they're both on the north coast
39:08What it means for the population we're not really sure
39:10We need to do a few more flights and spend a little bit more time out there
39:13But to find out if there are more of them, maybe it's the same two whale sharks out there every day. Who knows?
39:19It's fewer sharks than they were expecting but it's enough to get started
39:24Mark has just six days left to find out if hamish and the other whale sharks from ningaloo are visiting christmas island
39:34And to do this they plan to find photograph and tag as many of them as possible
39:41The spotter plane is now finding many more sharks
39:46It's right here
39:53But frustratingly as soon as they get close the animals are diving
40:04And as the days go by the difficulties of studying such an elusive fish are all too evident
40:12That's getting ridiculous don't you think
40:15Sorry
40:19Same old story i'm afraid get on the shark
40:22Boat up close to it just off the bow within distance to swim to it
40:27the thing dived straight away, but
40:29I didn't see see
40:31On the surface where I jumped in
40:33The water's gone with one day left. It looks like they'll go home empty-handed
40:40I'm over it makes it hard to tag them though when you can't see i'm over it
40:44I'm over it
40:46Bye mark
40:50Ten o'clock
40:56Then on the very last day just hours before their flight a final opportunity presents itself
41:14Here we're going
41:19It's a friendly shark good god, I didn't know they existed
41:23So
41:42Christmas island was nothing if not dramatic
41:47We spent two weeks there fruitlessly searching for whale sharks and
41:51In the final day we finally got some
41:56In fact we got a lot we got the seven tags out
42:03It was absolutely fantastic end to the trip
42:10And
42:11Remarkably, we even got a whale shark that managed to do a poo for us
42:16It's such a rare event i've only ever seen it twice with the hundreds of whale sharks i've swum with
42:23And it's so significant because the dna in that sample is worth gold
42:32And here it is whale shark poo
42:37Tip it out and there it is
42:40that
42:40Little reddy brown soupy mixture there if we can extract the dna out of this
42:46It's going to tell us something about why the whale sharks are coming to christmas island
42:55And when the result comes in it proves mark's theory the sample is packed with red crab dna
43:02So
43:04The results of the poo analysis are pretty exciting
43:08They tell us that the migration of these sharks from ningaloo to the north is not some random thing
43:13These sharks are actually directing their movements. They're going to christmas island for a reason
43:19There's a whole pile of food up there and these sharks are feeding on it
43:23So the next question is where do they go after christmas island? Do they come back to ningaloo or do they go somewhere else?
43:32So
43:37In the weeks that follow all seven sharks remain around the island
43:42But after a month only one tag is still transmitting
43:48It's attached to a five meter male named finn and to mark's delight he's now on the move
43:54So
44:01First he travels north before heading southeast on a direct course back to australia
44:10It's an exciting development with ningaloo's coral spawn imminent could finn be returning on an annual migration
44:18But
44:23Then to everyone's surprise he changes direction
44:27In two months, he travels 2 000 kilometers before disappearing off the radar
44:37It looks like there's a problem with finn's tag
44:42But two weeks later he reappears in the bandar sea
44:48The dive data reveals he traveled 800 kilometers rarely coming close to the surface
44:56Mark wonders whether he was feeding on an unknown food source deep underwater
45:01Or perhaps he was avoiding the strong surface currents that run between these islands
45:07Then finn turns around and heads back to west timor
45:10To find out more
45:16It's here four months and 4 000 kilometers later that the tag finally falls off
45:28Washed up on a beach
45:30And it was found by a guy searching for turtle eggs
45:34The tag was still transmitting so I could actually see the guy and I could see his house where he was storing it
45:39Got one of our phd students to go and recover the tag, which he did
45:45And here it is
45:46and
45:47When we got the tag back, we I think we got some
45:50Pretty interesting clues as to why it came off in the first place
45:54see this
45:55Shark bite marks and it's been a pretty big shark too judging by the the distance between those scrape marks
46:03I think a couple of hundred kilos of
46:05Bitey shark hanging off the end of this has been the reason that the tag came off the whale shark
46:11And it could be the reason behind many of the tags failing
46:21As finn's journey ends mark is left to draw his conclusions from the remarkable data he's provided
46:27But 12 months and 20 satellite tags later is mark any closer to unraveling the mystery
46:33Of where ningaloo's whale sharks are going
46:41What I thought we'd see at the start of this study is we'd tag sharks in ningaloo
46:45And we'd see at least some of them go across the indian ocean as far as the seychelles
46:49And that's certainly what the genetic data was suggesting
46:52And that's certainly what the genetic data was suggesting
46:56But that's not what happened
46:58Moreover when we looked at the photo identification data
47:02There were no matches between sharks at ningaloo or sharks in the seychelles hundreds of sharks thousands of photos
47:09Not one shark in common. So I think this is basically wrong
47:13I suspect what's actually going on is the sharks that are over here
47:17And this side of the indian ocean stay within the same area and that's certainly what we saw
47:22For the sharks we tagged at christmas island. What does that mean for the sharks at ningaloo?
47:27Well, I actually think it's good news
47:29Look if the sharks are really truly moving all this way over to africa
47:34Conservation of them is is a much more complex question, but if they're actually just staying over here
47:39We only have to deal with our nearest neighbors
47:44Since this study mark has started an ecotourism project in western timor
47:50And now the prospects for ningaloo's giant fish look a little brighter
48:00But whilst the whale sharks have given up some of their secrets
48:04There are still many more questions to be answered before their future can be truly secured
48:19You