Animals.with.Cameras.S02E01.Oceans
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AnimalsTranscript
00:00People have spent years trying to film the most intimate and dramatic moments in the
00:13lives of animals. Wouldn't it be wonderful to see the world from an animal's point of
00:19view? She's returned to the place that I can't follow her. So in this series, it's the animals
00:25that are doing the filming to reveal the secret side of their lives we've never seen before.
00:33That is lovely. Designing pioneering mini cameras for a huge range of animals. Everything
00:43is made to measure. I would never imagine you would ever see that from a bat's point
00:47of view. And we've teamed up with scientists who want to learn about the challenges animals
00:53face to help protect them in the future. She is potentially showing us parts of the ocean
01:00that no one has seen before. In this special episode, we dive into the ocean to find out
01:08what do turtles get up to at sea? Can sharks help protect coral reefs? How do gannets find
01:17their food? And how do seal pups survive after being abandoned by their mother? This
01:26is Animals with Cameras. The first adventure starts here, Cape Verde. A cluster of tropical
01:43islands off the west coast of Africa. Sal is one of the driest and most barren. Although
01:51it looks like there's not much wildlife here, every summer the sandy beaches in the south
01:56are inundated with a very special reptile, the loggerhead turtle. Loggerheads can weigh
02:07twice as much as an adult human and live for up to 50 years. They spend their lives
02:15traversing the world's oceans all on their own, travelling thousands of kilometres between
02:21feeding grounds. Because they spend so much time in the open ocean, extremely little is
02:28known about them. So what do these creatures do at sea? Hopefully our cameras will find out.
02:36Biologists Albert Taschinera and Christophe Azagir have been studying the loggerheads on
02:46Sal for the past decade. They're trying to learn more about these animals so they can better
02:53protect them. Cape Verde hosts one of the world's largest populations of nesting loggerheads. During
03:02the breeding season, up to 7,000 females return to Sal's beaches where they were born. Each can
03:10lay up to six clutches of 80 eggs. It's widely believed that during the nesting season, loggerheads
03:17will not feed for five months. But is this actually true? Do turtles feed in the surrounding
03:24ocean or not? Albert and Christophe need to use our cameras to find the answer. I've been
03:31working in Cape Verde for 10 years and for almost as long as this time we have the speculation
03:37that turtles feed locally. So why is it important to know if they're feeding? The beaches of
03:45Sal are already protected to safeguard the turtles, but the surrounding coral reefs are not.
03:52So if the turtles are feeding here, the marine ecosystem needs protecting too. If we understand
04:00what they do, we can always push for better conservation strategies. But to safeguard the
04:07waters, first they need evidence. Something that onboard many cameras should be able to help with.
04:13As night falls, the turtles begin to arrive on the beaches. It's Albert and Christophe's
04:23opportunity to survey the nesting females. Albert makes a quiet approach, so not to disturb this
04:31female. They're looking for a turtle that's big enough to carry the camera with ease.
04:44She looks big. She's around 80, 81, 80 centimetres long. That's big enough.
04:55And this is the camera she'll be wearing. There's a high-definition camera that will
05:01give us a turtle's eye view and a series of attachment points that will dissolve after
05:06a few days at sea. And all being well, that's when the camera floats up to the surface.
05:14Once the turtle has finished laying her precious eggs, Albert and Christophe
05:19work swiftly and silently to collect valuable data for their ongoing research.
05:27Then they place a temporary box around her to keep her safe.
05:36Her shell or carapace is given a clean and the camera's attached
05:40using an environmentally friendly resin.
05:45Once the camera anchors have eroded away, this too will be shed over the coming days.
05:52Just over an hour after she first heaved herself onto the beach,
05:57our turtle is reunited with the ocean. Now it's over to her to film her secret world.
06:05But only if all of this technology works.
06:08Fingers crossed we'll get our camera back in 24 hours' time.
06:21More than 80% of the ocean is unmapped and unexplored.
06:27Even the lives of the most notorious marine animals harbour secrets.
06:31You might think we know all there is to know about sharks,
06:34but as they live at sea and can swim at high speeds, they're incredibly tricky to study.
06:41So our understanding of their lives is actually quite limited.
06:45But our on-board cameras can help change that.
06:50Scientist Dr Tristan Guttridge has been studying sharks in the Bahamas for the past 15 years.
06:5615 years.
06:58Tristan has come to the island of Andros, home to one of the largest coral reefs in the world,
07:04measuring over 220 kilometres long.
07:08It's a magnet for several species of shark who rely on it for food and shelter.
07:14Reef sharks, lemon sharks and great hammerheads patrol the area.
07:21Even one of the biggest predators in the ocean, the tiger shark, lives here.
07:27Around the world, coral reefs are dying at unprecedented rates
07:32due to pollution and climate change.
07:35Tristan needs to check the health of the Andros reef
07:38to ascertain if these sharks will have a home in the future.
07:42Doing this with a team of scuba divers would be an enormous task that could damage the coral.
07:48So the best guide to this vital underwater habitat is the sharks themselves.
07:53As a human, I can only spend about an hour underwater
07:56and I'm limited to certain depths as well.
07:59But a reef shark, it can act as essentially a surveyor for many, many hours.
08:05And so we can actually look at the health of the system that it's swimming in and patrolling.
08:11Tristan wants to enlist the help of Caribbean reef sharks.
08:15They spend most of their time around the coral,
08:18making them perfect to carry the cameras.
08:22Tristan is tagging sharks as part of his ongoing research,
08:25so this is a good opportunity to add our on-board technology.
08:31He's helped by shark expert Grant Johnson.
08:34And to catch the sharks, they're using a simple float system.
08:38We can actually get to that animal really quickly,
08:40so it's a very effective way and safe way to catch sharks.
08:45It's a very safe way of fishing for these animals,
08:48because we can bring the shark to the side of the boat,
08:51work it up, measure it, place our camera tag in a short period of time.
08:56And within minutes, they're in luck.
09:00How much the float moves is an indication of how big the shark is.
09:05Look at the buoy, man. The buoy's getting pulled down.
09:08That is not small that's towing that around.
09:11That is definitely not small.
09:13I'm saying ball.
09:14I'm predicting... Look at that.
09:15I mean, if it is a ball...
09:17Look at that.
09:18Look at that.
09:21Oh, my God, dude.
09:23That is a three-metre tiger shark.
09:27OK.
09:28Tiger sharks are at the very top of the food chain.
09:31They'll even eat other sharks.
09:33But its own safety is top priority, so the team works carefully.
09:38We got her. We got her.
09:40It's incredibly rare to catch this species,
09:43and Tristan wants to make the most of it.
09:46Like reef sharks, tiger sharks use coral habitats,
09:50but they explore other environments too.
09:53So if we can attach a camera, we can analyse the wider ecosystem
09:57through the eyes of one of the world's greatest predators.
10:04Our onboard system has been designed with the anatomy of the shark in mind.
10:08It can operate down to 500 metres, film in HD,
10:13and even record depth and temperature.
10:17With everything safely attached,
10:20it's time for this incredible predator to capture its underwater world.
10:30Away she goes.
10:31Away she goes.
10:39Unbelievable.
10:40Wow.
10:42Good work.
10:42Unreal.
10:43How's your back?
10:44Totally fine. Totally fine.
10:46I was not expecting that.
10:48This is becoming very interesting indeed.
10:52Wow.
10:56Five hours later, the camera automatically comes off.
11:01But finding it in the open ocean is a tricky task,
11:04so Tristan is relying on more technology.
11:09Another 20 seconds.
11:11The camera is equipped with a satellite beacon,
11:14which Tristan can detect on this handheld device.
11:18Tristan needs to find the tag quickly
11:21before it gets swept out to rougher seas beyond the reef.
11:27Suddenly, a flash of orange stands out against the blue.
11:32How did I know Grant would spot it?
11:36Camera's still on it?
11:38Yeah.
11:40The LED's still on.
11:43Disco, disco.
11:47I'm very happy.
11:48Tag's intact.
11:50No evidence of rubbing or anything.
11:52The satellite tag worked perfectly.
11:55Let's hope there's some magic in here.
11:57It's going to be amazing to see what's on there, dude.
11:59It just went down to the bottom of the ocean.
12:00I know, I know.
12:02Very excited.
12:03It's a brilliant success.
12:05And back on dry land, Tristan and Grant take a look at the footage.
12:13The shark is swimming much faster than they imagined,
12:16far quicker than a scuba diver.
12:19She's passing through small patches of coral and seaweed,
12:22and she's in relatively shallow water.
12:26But then she approaches an enormous drop-off.
12:31This reef wall is the edge of a deep sea basin
12:34known as the tongue of the ocean.
12:37And this tiger shark heads straight to the bottom.
12:42From the depth gauge built into our camera,
12:44we know that the shark is 160 metres deep.
12:49That's more than five times deeper
12:51than the average scuba diver is allowed to go.
12:55So this shark is potentially showing us parts of the ocean
12:58that no one has ever seen before.
13:02This footage has helped Tristan see what the shark sees.
13:06And he thinks it may have dived deep
13:08to search for the prey in the water above.
13:11As a fast-moving ambush predator,
13:13it can swim along the seabed
13:15and then launch an attack from below without being seen.
13:19The camera's in-built thermometer
13:21also shows it's five degrees colder down here
13:24than at the surface.
13:25This cold, deep water helps a shark cool off
13:28after hunting in the warm, shallow sandflats,
13:31letting it stay in peak performance mode,
13:35critical for an apex predator like this.
13:39After five hours, the tag comes off safely
13:42and floats to the surface.
13:46It's a promising start,
13:49but Tristan still needs to deploy the camera
13:51on one of the most important species in the ecosystem.
13:55Caribbean reef sharks.
13:57He hopes they'll take us close to the coral,
14:00letting us see how healthy the local reef is.
14:04So the team will try again another time.
14:13Back in the Atlantic Ocean on the island of Sal,
14:16our turtle cam has been deployed for 24 hours.
14:19Biologists Albert and Christoph need to find out
14:22if the loggerheads feed here during the nesting season.
14:28If we can film this behaviour,
14:30it will prove that this marine ecosystem
14:32is vital for the turtles and needs protecting.
14:37But first, we have to get the camera back.
14:42It has surfaced somewhere out at sea.
14:45It's a bit of a mystery.
14:47It has surfaced somewhere out at sea
14:49and its GPS has sent out a signal.
14:54But we can only get to GPS location every few hours.
14:59So it's a race to find the camera
15:00before the current carries it off course.
15:04To help us, we're also using a VHF radio antenna.
15:09But sometimes our own eyesight
15:12is better than the latest technology.
15:16Here it is!
15:19We got it!
15:27But will our footage provide the insight
15:29that Albert and Christoph have been waiting for?
15:32Will it show her feeding in local waters?
15:37Time to take a look with Albert and Christoph back at the lab.
15:44The view from the camera is crystal clear.
15:47And straight away, our turtle rewrites a common scientific theory.
15:53Female loggerheads were thought to be solitary
15:55during the nesting season.
15:59But this footage proves that they do interact with one another.
16:03Far more than was ever expected.
16:09There's not just one extra turtle here, but two.
16:17And there's another surprise discovery
16:21when this turtle encounters a sunken anchor.
16:32She is feeding during the nesting season.
16:38She's eating the seaweed attached to the anchor.
16:46Loggerhead turtles will eat a range of food,
16:49including jellyfish, sponges, seaweed and even shrimp.
16:58This is the evidence we were looking for.
17:01It proves that these turtles do feed
17:04during their five-month breeding season.
17:07So this marine ecosystem needs more protection.
17:13And that can't come soon enough.
17:15Based on what she films next.
17:19It's a discarded fishing net
17:21that's smothering a large part of the reef.
17:27The turtle is clearly trying to feed through the net.
17:31But if she accidentally swallows it,
17:33it could have a negative effect on her health.
17:39It's a stark reminder of why these waters need safeguarding.
17:46Thankfully, our turtle swims off and out into deeper water.
17:57And she feeds again, this time on a jelly-like sea squirt.
18:05She appears to be grazing on various foods.
18:08And Christophe thinks that this might help top up her energy reserves
18:12after coming on land.
18:15But it's not easy for a turtle on land to lay her eggs,
18:19which is a tiring process.
18:28Dive and feed complete, she heads towards the surface for a breath.
18:34But before she gets there, she encounters another turtle.
18:38And this one is covered in barnacles and seaweed.
18:41An indication that it's very old.
18:47It looks as though our turtle is eating seaweed
18:50from the back of the older one.
18:54There's so much life not only growing on this turtle,
18:57but also following it around the sea.
19:00It's a mini swimming ecosystem.
19:04It shows that by protecting these turtles,
19:07many other species will also benefit.
19:12Seeing this socialising behaviour is incredibly rare.
19:17Without this video camera, Albert and Christophe
19:19would have never known these turtles spend so much time
19:23around one another at the surface.
19:29The Cape Verde aggregation of loggerhead turtles
19:32is thought to be the second largest in the world.
19:37So it's vitally important that they're given the protection they need.
19:41If they disappeared, the entire species would be at risk of extinction.
19:51This turtle's footage brings new insight
19:54into the loggerhead's hidden world.
19:58Revealing that they're more social than we ever imagined.
20:02And that they do feed during the nesting season.
20:05A world first for science.
20:08And it's the proof that Albert and Christophe
20:10needed to push for greater protection of these vital waters.
20:15And hopefully safeguards the future of this beautiful species
20:19on Cape Verde for many years to come.
20:32It's not only animals that live beneath the waves
20:35that have a hidden side to their lives.
20:37One particular species can take our cameras on land,
20:41in water and up in the air to solve some mysteries.
20:50Gannets.
20:53They're one of the most aerobatic seabirds in the world.
20:57Renowned for their spectacular high dives,
20:59they can drop like an arrow from over 30 metres up
21:04and strike the water at 80 kilometres per hour.
21:08These feathered torpedoes can plunge 20 metres underwater
21:12where they can pick off their meal.
21:15To protect themselves during these legendary stunts,
21:18they're equipped with extremely strong neck muscles
21:22and a spongy plate of bone at the front of their skull
21:25to cushion the impact.
21:27Gannets can fly up to 400 kilometres away from their nest,
21:31making them extremely difficult to study.
21:35As a result, there are a lot of unanswered questions
21:38about these seabirds.
21:41They're famous for their incredible hunting skills,
21:44but how do they find small shoals of fish
21:47hidden underwater in the wide open ocean?
21:51This is a show of the Gannets.
21:53In Ireland, Dr Mark Jessop is trying to unravel
21:57some of the Gannets' mysteries.
22:00He's been using GPS trackers to find out where the birds go,
22:05but he has no idea what they're doing out at sea.
22:10In 60 years, seabird populations in general,
22:13including people who have never seen a seabird before,
22:16have been reduced to a handful of seabirds.
22:19In 60 years, seabird populations in general,
22:22including puffins, have declined by 70%.
22:26But not Gannets.
22:28They are thriving.
22:31Mark wants to use our cameras to see how Gannets find their food,
22:36because he thinks that's what makes them so successful.
22:41Gannets are a really fascinating species.
22:43You know, they're one of those species
22:44that have bucked the trend of global seabird declines,
22:47and Gannets tend to be increasing in populations.
22:50So we really want to understand how and why they're doing it.
22:52One of the theories is that they're getting supplemental food
22:55from humans through fisheries discards.
22:57Ideally, I'd love to see something like fishing vessels,
23:01perhaps other animals, you know, pie in the sky.
23:04Maybe we'll see some dolphins
23:06and feeding associations with dolphins.
23:08You know, the sky's the limit here, really.
23:12If Mark can discover how Gannets find their food,
23:15he can work out how to help other seabirds that are in decline.
23:20So we need a camera that's waterproof and lightweight,
23:23yet strong enough to withstand a big impact.
23:27It's one of the hardest challenges we've ever faced.
23:31Tackling the task is tech wizard Chris Watts.
23:35He's built cutting-edge cameras for an incredible variety of animals,
23:40and he spent three months developing a bespoke Gannet camera.
23:45This is his solution.
23:48It can record in HD, film in slow motion,
23:52and it's been fitted with a wide-angle lens,
23:54so when it's mounted on the bird's tail,
23:56it will capture all of the action.
23:59And it weighs just 60 grams.
24:02That's 2% of the Gannet's body weight.
24:06Easily light enough for them to fly with,
24:08and the battery should last for almost two hours.
24:12Packing this much technology into such a small space
24:16is an incredible achievement.
24:18But can it deal with the impact of hitting the water at high speed?
24:24When Gannets strike the surface of the sea,
24:27they experience almost 9G as they decelerate,
24:31which is more than most fighter pilots can contend with.
24:35To see if our camera can withstand such high forces,
24:39Chris is going to some extreme measures to put them to the test.
24:48Today, this is the moment of truth, really.
24:50If it's not waterproof and it can't take the impact of hitting the water,
24:54then it's all for nothing.
24:55To simulate a Gannet dive,
24:58Chris is strapping the camera to an arrow,
25:01ready to be fired out to sea.
25:08A fishing reel brings it back to shore for inspection.
25:39And it survived the impact.
25:43A triumph.
25:44Even after repeated trials, the camera remains intact.
25:49Now it's time for the real thing.
25:55Five kilometres out in the Irish Sea,
25:58Mark and his team are heading to the remote Salty Islands,
26:02home to over 7,000 breeding Gannets.
26:05The on-board camera will only record for two hours,
26:09so the team needs to recruit a Gannet that's just about to go fishing.
26:13Otherwise, the camera batteries will run out before the bird even takes off.
26:20The parents work in shifts.
26:22While one guards a chick, the other goes foraging for up to four days.
26:27They then swap over, and that's the moment they've all been waiting for.
26:30Up to four days.
26:33They then swap over, and that's the moment Mark is looking for.
26:37We've just had one come in, Mark.
26:39Do you want one on the left, who's just fed the chick?
26:41So you want one on the right?
26:42Yes.
26:43OK, let's get him.
26:45Mark's research project means he has special permission to catch these adults.
26:57The chick is safe with the other parent,
27:00and when our bird is bagged, it relaxes and Mark can do a few essential health checks.
27:06That's three kilos exactly.
27:10This one is in top condition, a perfect candidate for carrying our camera.
27:17It's attached to the central tail feathers, which are strong and stable.
27:21Being this far back also helps protect the lens,
27:25so it won't get knocked as the Gannet plunges into the sea.
27:29This tape should hold the camera in place,
27:32but it's soft enough that the bird could rip it off if it's not comfortable,
27:36which means there's a very real risk these cameras won't come back at all.
27:44Have it?
27:44Yep.
27:46With everything in place, it's time for this bird to reveal its secret life at sea.
27:53It flies off nice and strong, comfortable with its new accessory.
28:00Mark and the team get to work deploying another camera.
28:04And after just 24 hours,
28:07the first member of our feathered film crew returns with our camera intact.
28:14Just truly looking forward to seeing this fantastic bird back at sea.
28:27And after just 24 hours the first member of our feathered film crew
28:32returns with our camera intact.
28:44forward to seeing what's on the camera. You have no idea. He's had a very successful foraging trip.
28:49I think he feels very heavy. Oh, you fatty! This gannet has put on 400 grams since it was caught
28:56yesterday, so Mark knows it's been fishing. We just hope that the camera was running at the
29:02right time. The bird is given a careful health check and released back into the wild.
29:15Then the team can take a look at the first batch of footage.
29:20Look at that! Oh, that's so cool. Oh, that's just beautiful.
29:27The on-board footage shows just how close to the water these birds can fly. Mark and his team think
29:34this footage could be useful to other scientists investigating the effect of wind farms on seabirds.
29:42These gannets seem to be flying well below the sweep area of a turbine,
29:46so they should be at little risk of collision.
29:48And to their delight, the team have captured some diving behaviour.
29:54Look at that! Oh, my goodness me! That is lovely. I have always wanted to see that.
30:06Yeah, the trip was worth it for that one alone. The footage also provides evidence
30:11that these birds are either right or left-handed. Each gannet always dives in the same direction.
30:18This one always dives to the left. Having a dominant hand, or in this case a wing,
30:25can improve efficiency in complex tasks, which could be important during the gannet's high-speed dives.
30:34It's a brilliant start, but because action happens so fast,
30:38it's hard to see how the gannets are finding their food.
30:41So the team sets out to get more on-board footage,
30:45but this time the cameras are set to record in slow motion.
30:48So this time, we should see precisely how they're finding the fish.
30:57In total, seven gannets take our cameras out to sea and return them safely back to the colony.
31:04And after carefully analysing the footage, Mark can see exactly how the gannets are finding their food.
31:14In this sequence, it's possible to see common dolphins at the surface of the water.
31:21They're likely to be feeding on fish, and this gannet is clearly trying to do the same thing.
31:28Underwater, the camera's in-built microphone has even recorded their calls.
31:38Mark believes the birds are using the dolphins to help find their food.
31:44And he's following the gannet to see how it's doing.
31:49Mark believes the birds are using the dolphins to help find their food.
31:56And he's found evidence that they're following other marine animals too.
32:02By going through the footage frame by frame, we can see two whales, or at least two whale blows.
32:10And this gannet immediately turns towards them, and within 16 seconds, it's diving, searching for more fish.
32:19It indicates that gannets are using other animals to get a visual clue.
32:25If whales and dolphins are in the area, then there's a good chance there's food there.
32:31Seeing these behaviours would never be possible without these on-board cameras.
32:37The footage shows that gannets are using other species to effectively find small patches of food in a large open habitat.
32:46And this has big implications for how we conserve them.
32:50In order to preserve gannets, it's important to preserve all of the animals they rely on to find food.
32:58Which means protecting whale and dolphin populations, because all of these species are interconnected.
33:04Therefore, it's critical to take an ecosystems approach to conservation.
33:11In general, seabird populations are declining, partly because of a drop in fish stocks.
33:17But gannets don't seem to be affected, and our footage shows why.
33:23In the distance, it's possible to make out a fishing vessel on the horizon, and this gannet flies straight towards it.
33:31And lots of others have had this same idea.
33:36There's over 100 here, and they're diving in to catch discarded fish.
33:42It indicates that gannets may have learnt to follow fishing vessels to find food.
33:48Importantly, there are very few other seabird species capitalising on this free meal.
33:54It's almost exclusively gannets here, and they can be quite aggressive.
34:01It seems they're out-competing other birds for this fish.
34:05By exploiting fishing vessels, they get access to a steady supply of food, even when their prey is in decline.
34:15The onboard cameras have been a success.
34:19They've shown us how these birds use other animals, and even fishermen, to find their next meal.
34:31Back in the Bahamas, shark scientist Dr Tristan Guttridge is trying to deploy our cameras on some Caribbean reef sharks.
34:41They can swim further and faster than any diver, so they can show us how healthy this ecosystem is.
34:51They're one of the most abundant shark species in the Bahamas, and also one of the most important,
34:57both ecologically for their role in the coral reef system, and also economically,
35:03as a huge number of people come from all over the world to dive with reef sharks.
35:09And it doesn't take long to find one.
35:13Oh boy. Perfect size once again.
35:18Every shark that Tristan catches is measured and tagged as part of his long-term study
35:23to understand the abundance and distribution of sharks in the area.
35:27And 189. Nice big male reef shark.
35:32Right, let's put the tag on.
35:35This is basically a microchip tag that has a unique number, and you put it in the muscle next to the dorsal fin.
35:44And the idea is it's literally the size of a grain of rice, and it would be what you would put in your dog.
35:51And every time you pass a reader over it, it activates and tells you that number.
35:55So we're able to actually ID this animal, hopefully for the rest of its life.
36:00We try and be as gentle as we can. We're also trying to do this as quickly as possible,
36:04so that we can get that shark off and swimming.
36:07The microchip provides important basic information,
36:10while the camera gives us a shark's eye view of their world.
36:15The camera mount has soft pads on the inside of the clamp, which gently hold it in place.
36:22OK, are we ready? Hang on.
36:25Yeah.
36:45Over the next few days, Tristan and Grant managed to deploy four more shark cameras
36:50along different sections of the reef, to help get a good overview of the area.
36:56Perfect.
36:58Right, I think we're ready to release.
37:01Wow.
37:03Mature, about 1.7 metres long.
37:07Hopefully it will share some secrets with us about the health of this system.
37:12It swam off great. We didn't have it alongside the boat very long.
37:15I'm really excited. Awesome. Well done, everyone.
37:19Each camera will record vital information about the health of this ecosystem,
37:24so it's critical Tristan and the team find them again.
37:30They listen out for the satellite signals.
37:33There it is!
37:34And hone in on the cameras.
37:36Ha-ha!
37:38Yes!
37:39They're good at this.
37:42They're like half twelve, one o'clock.
37:45Yes!
37:47Fantastic.
37:51In total, the sharks have captured almost 25 hours of on-board footage,
37:56giving us a much more detailed look at their world than any diver could achieve.
38:03This is pretty cool.
38:05Look at that, look at that. Oh, big barracuda.
38:09I love being able to see what they're seeing.
38:15But what the sharks have filmed is worrying.
38:19There's a layer of algae covering much of the reef.
38:26Too much algae can reduce the oxygen levels and block the sunlight,
38:32which then has a negative effect on everything in the food chain,
38:36from wrasse to reef sharks.
38:41Local fishermen could be putting a lot of pressure on the reef fish
38:45that would normally eat the algae and help maintain the health of the system.
38:51But it's not just overfishing.
38:54Pollution and climate change could also be to blame and contribute to this thick algae.
39:00These are global issues and will only get better
39:03if we continue to reduce our impact on the natural world.
39:07The cameras have provided a great insight into the health
39:10of some of the most remote corners of this reef.
39:14But they've also revealed some surprising shark behaviour.
39:20They're swimming far closer to the reef than anyone expected.
39:24They can weave through the intricate coral tunnels and archways.
39:29Tristan and Grant believe this could be a strategy
39:32that the shark is using to help hunt for food.
39:36By staying close to the reef structure, it may be able to ambush a fish
39:41before it has a chance to escape into one of the many hiding places.
39:50Reef sharks can sniff out prey or use special electroreceptors
39:55to detect the heartbeat of their next meal.
39:58But it's hard to catch a fish before it escapes into the reef.
40:02So by weaving through the coral, there's a chance this shark
40:05can sneak up on its next victim.
40:08It might also keep them hidden from bigger predators like tiger sharks
40:12who, as we know, patrol this area.
40:16Seeing this behaviour is something that only our cameras could reveal.
40:20As soon as a diver enters the water, the sharks behave differently
40:24and there's no way a human could keep up with them
40:26through these tight coral corridors.
40:29Whoa.
40:31Ah, that's when the tag came off.
40:36No matter how much scuba diving you do,
40:38you're never going to be able to spend that much time with a shark.
40:41Exactly. And that's the big difference.
40:43That's the thing that these tags do for us,
40:45is we get five hours of uninterrupted footage
40:48of where these animals are going and how they're using their habitats.
40:52The cameras have been a success,
40:55showing us that these sharks can hunt among the coral
40:58in ways Tristan had never seen before.
41:01And the footage proves that this reef needs further protection
41:05from the global impact of mankind if it's to remain a shark mecca.
41:13Our oceans support some truly gigantic animals
41:17and our next mission is on the coast of California,
41:21in Anunuevo State Park,
41:23where giants come ashore to breed.
41:28These are northern elephant seals.
41:32The bulls can reach four metres long and weigh over two and a half tonnes.
41:38They battle to become beach master.
41:45Despite their blubbery appearance,
41:48these animals are extreme athletes.
41:52They swim 9,000 kilometres a year
41:55and can dive one and a half kilometres deep,
41:58drop their heart rate to just three beats per minute
42:01and can hold their breath for two hours.
42:08Every winter, this area becomes a huge creche,
42:12filled with over 2,000 females,
42:15each giving birth to a single precious pup.
42:20But after just four weeks,
42:23the mums head out to sea and abandon their young forever.
42:30Scientists Roxanne Beltran and Patrick Robinson
42:34know a huge amount about the lives of the adults
42:37but very little is understood about the pups
42:40and they want to find out more.
42:42The mums actually leave before the pups ever go into the water.
42:46So these juveniles, when they become independent from their mums,
42:50are trying to figure out how to be seals.
42:53They live off their fat reserves from their mother's milk
42:56for the next two months before they head out to sea and fend for themselves.
43:02During this time, they train for adult life,
43:05much of which is done underwater,
43:07where they can swim faster and further than we can,
43:10making it hard to study them.
43:15With any luck, our onboard cameras will show what these pups are doing
43:19to prepare themselves for adult life.
43:25Roxanne and Patrick find four young seals to carry the cameras.
43:30Although the pups are only a few weeks old, they're already enormous.
43:35They put on 90 kilos in their first month.
43:38Fuelled by milk which is 55% fat.
43:42That's more than double cream.
43:46After a few health checks, our specially designed onboard cameras
43:50are attached with a temporary non-toxic glue.
43:57During the procedure, Roxanne and Patrick monitor the pups' heart rate
44:01and respiratory rate to ensure it stays safe and healthy.
44:09The cameras will record for 16 hours and have been designed
44:12to withstand the crushing pressure of deep water.
44:19Once they've returned safely,
44:21Roxanne and Patrick are able to analyse the footage.
44:25Oh, wow.
44:28What is she doing?
44:32They are more graceful than I thought, based on how they are on land.
44:37Swimming with the seals gives Roxanne and Patrick an entirely new perspective.
44:42And the footage provides a real revelation about how social the pups are.
44:49When adults go out to sea, they don't interact with one another at all.
44:53They're completely solitary.
44:55So it's surprising to see these pups being so interactive with each other.
45:01Roxanne thinks that the young seals might be socialising like this
45:05to help their development.
45:07With no parental guidance, they may be learning from each other instead.
45:14In all of the footage, the pups only ever swim in shallow water.
45:19Roxanne and Patrick think that's because they're too fat to dive deep.
45:24Despite being so heavy, all of their blubber makes them really buoyant.
45:30They need all of their fat reserves to survive a long period without food,
45:35while they learn how to catch their own meal.
45:38But at the same time, it makes swimming and hunting difficult.
45:42So it seems to be a trade-off.
45:45Swimming around these shallows, the pups seem to investigate anything they come across.
45:51Even bits of rubbish.
45:53Is that a plastic bag?
45:56It's unlikely to mistake this plastic bag for food,
45:59but they have been known to get tangled up in waste,
46:02and this playfulness could explain how that happens.
46:08The cameras also reveal that these mischievous pups often chase the local fish.
46:13They're not catching them, but it's all good practice.
46:18And it's not just the fish they're toying with.
46:21Surprisingly, they spend a lot of time playing with seaweed.
46:26What is she doing?
46:28Did she grab it?
46:29Yeah.
46:31She's dragging it around.
46:34What?
46:36Playful practice is important in the development of many young animals.
46:41For these seals, it may help build those important diving skills,
46:45which later they'll rely on.
46:52After their in-water training, it looks like they come out for a rest on the beach.
46:57But the scientists have a very different theory.
47:00It's hard to see to the untrained eye, but the seals seem to be holding their breath.
47:07Just like an athlete would train for a marathon by doing further and further runs,
47:12these seals are holding their breath for longer and longer,
47:16developing their physiology so one day they'll be able to hold their breath for long enough to catch a meal.
47:26This seal holds its breath for almost 12 minutes,
47:30so it's got some practice to do before it can manage two hours like the adults.
47:36By filming themselves, these pups have shown us how they prepare for life at sea.
47:43After being left alone without a mother, they seem to train together,
47:48trying to hunt, exploring the environment and practising to hold their breath.
47:53Key skills that will make them elite ocean divers.
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