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A scattering of some 700 islands in the Atlantic Ocean, the Bahamas are home to one of the largest and most diverse shark populations on the planet.....
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AnimalsTranscript
00:04Sharks. Nature's perfect solution to an underwater life.
00:10They've been swimming in the oceans for over 400 million years.
00:14And as top predators, play a vital role in keeping our seas healthy and productive.
00:23But they're coming under increasing pressure. Millions are hunted and killed every year.
00:31Never have sharks needed friends more than they do today.
00:39For three weeks, I've been in the Bahamas for Blue Planet Live.
00:46Watching, monitoring and diving with one of the richest shark populations on the planet.
00:55I want to reveal why sharks are thriving here and find out if there are lessons to be learned from
01:01these crystal clear waters that could help secure their future elsewhere around the world.
01:15A good afternoon, without approaching the least.
01:16At the time of the world, the most costly emotional experience is the SEMX Two.
01:17I can't believe in many of these crystals.
01:32SEMX Two.
01:38They can't believe in many of these crystals.
01:38They can't believe in many of them.
01:45Our blue planet is home to more than a thousand species of shark
01:50and their cousins, the rays.
01:57They come in a myriad of shapes
02:04and sizes
02:07and are found across all of our oceans
02:10from the tropics
02:13to the Arctic
02:14and into the deep abyss.
02:21There are a few places where the number and diversity of sharks
02:25is unparalleled.
02:29The Bahamas is one of them
02:31earning it the title of shark diving capital of the world.
02:40700 islands are scattered over 84,000 square miles of ocean.
02:50This location is unique, perched on the edge of deep water
02:55where the seabed plunges to a depth of 4,000 metres.
03:02The meeting of shallow water and deep, open ocean
03:06leads to a profusion of life.
03:14In winter, the resident Caribbean reef sharks
03:18and bull sharks
03:20are joined by visitors
03:23bolstering the shark and ray population
03:25to 78 species.
03:42In 2011, the Bahamas were declared a shark sanctuary,
03:47making it illegal to fish for or kill any species of shark.
03:59These protected waters offer me a unique chance
04:02to get close to these amazing top predators
04:07and to see firsthand what it takes
04:10to have a healthy, thriving population of sharks.
04:20Within seconds of coming down here,
04:23I'm greeted with one of the most dazzling displays
04:27you'll ever see underwater.
04:29Shhh.
04:43There's probably two or three different sort of shark
04:46at this location,
04:48but the dominant kind
04:49is going to be the Caribbean reef shark.
04:52Shhh.
04:53And I can already see at least 20 of them
04:55here in the water around us.
04:58Shhh.
04:59And I guess the first question that people would ask would be,
05:02Shhh.
05:03Isn't it dangerous?
05:04Isn't it risky to be surrounded by this many apex predators?
05:08Shhh.
05:09And I have to say,
05:10Shhh.
05:10I feel just as comfortable being in here
05:12surrounded by all these extraordinary animals
05:15as I would do going for a walk with a pack of poodles.
05:22These animals are so good at sensing their environment.
05:27They know what's prey in the water around them
05:30and it's not us.
05:32They may well swim in close,
05:34but at the last second they just bank away.
05:36They could not be less interested.
05:38Shhh.
05:39And the statistics about sharks prove that's true.
05:43Shhh.
05:43Around the world.
05:44Shhh.
05:45You're more likely to be killed taking a selfie
05:47than you are to be killed by a shark.
05:50Shhh.
05:52In fact, statistically speaking,
05:54the chance of being killed by a cow, a deer
05:57or even a vending machine is higher
05:59than the risk posed by one of these.
06:08Sadly, this abundance of sharks
06:10is not typical across all of our oceans.
06:14Shhh.
06:15This is not a sight that you get to see just anywhere.
06:19So, around the world, we human beings
06:21are taking at least a hundred million sharks
06:24from the world's oceans every single year.
06:29In some places, sharks have declined by over 90%.
06:34And in the time it'll take for you to watch this programme,
06:38over 11,500 will be killed.
06:43It's a number that simply cannot be sustained.
06:46If it carries on like this,
06:47then our children will not have the opportunity
06:50to dive in seas like this,
06:52surrounded by these stunning predators.
06:57The Bahamas isn't the only place
06:59to offer protection to sharks.
07:02Today, a total of 17 sanctuaries
07:05have been created around the world,
07:07covering over 7.5 million square miles.
07:12But this still amounts to only 5% of our oceans.
07:19Sharks need more help.
07:22And if we don't give it to them,
07:24much of the life in our oceans will suffer.
07:28As apex predators,
07:30they remove any sick or injured animals,
07:33keeping fish stocks healthy.
07:36Animals below them in the food chain are kept in check.
07:40And removing sharks would unbalance whole ecosystems.
07:46Over 3 billion people depend on the ocean
07:49for their livelihoods.
07:52It's essential we protect sharks for our sake,
07:56as well as theirs.
07:58And a vital step towards this
08:00is combating the reputation of fear
08:03that many sharks still hold.
08:05the ocean.
08:17I always had a passion for the ocean.
08:21I fell in love with scuba diving.
08:24I fell in love with everything.
08:26It was a calling, I think.
08:37Christina Zanato left her homeland of Italy
08:40over 20 years ago,
08:41heading for the Bahamas.
08:46Ever since, she's become an advocate for sharks.
09:00And two decades of diving at one site
09:03off the island of Grand Bahama
09:04has convinced her that these animals
09:06are a long way from being mindless killers.
09:13Christina is known locally as the shark dancer.
09:21And this is her stage.
09:26I love that there is a busy silence.
09:37It is the most peaceful and calming moment of my day.
09:47My babies are Caribbean reef sharks.
09:54I love watching their behaviours and their interactions.
10:01They appear to me as different
10:04as any other human being that I encounter.
10:08Some of them are more dominant.
10:11Some of them are shy.
10:15And some seemingly seek out a closer encounter with Christina.
10:22The first time that shark settles in my lap,
10:28and every time she settles in my lap,
10:31and I feel her weight over my legs,
10:33that is the most amazing feeling.
10:37And there's nothing to this day that beats that.
10:45You can feel everything about the shark.
10:48You can feel that it is a living, breathing creature,
10:53that is aware of her surroundings,
10:56that is aware of what I am doing to her,
10:58that is aware of my touch.
11:01And the suit might actually have a nice feeling to their skin.
11:07These sharks are eight feet long.
11:11I can never force an animal of that size
11:13to do anything or to sit anywhere.
11:18It's their decision to come in.
11:20It's their decision to stay.
11:22It's their decision to go.
11:29There is a total disconnect from humans to sharks.
11:36We can swim in the ocean with sharks in a way
11:40that you can never walk around on the snow
11:43with a polar bear following you.
11:47We have to make that connection with the sharks.
11:51Understanding there are way, way less dangers
11:53than many creatures out there.
11:59Christina's unique relationship with sharks
12:01allows her to do something quite extraordinary.
12:13She can take out fishing hooks that are caught in their mouths.
12:25Over the years, she's removed more than 300 hooks.
12:41We must change our ways because we need to protect the oceans
12:45and we need to protect the sharks.
12:47And when you reach that message,
12:50then you have a victory.
12:57A greater understanding of these misunderstood creatures
13:00can undoubtedly help sharks.
13:07And with such a diverse and healthy population on its doorstep,
13:13the Bahamas has long been at the forefront of global shark research.
13:21The Bimini Biological Field Station, or Shark Lab,
13:25has been increasing our knowledge of sharks and rays
13:28for the last 29 years.
13:37Heading this institute is Matt Smuckle,
13:39who's had a passion for the marine world for as long as he can remember.
13:45My first memories were snorkeling in the Florida Keys.
13:48Growing up, I always had an affinity and a connection with, you know,
13:51spending pretty much every weekend and all summer in the ocean.
13:55My favorite group of animals are the sharks.
13:57That's what originally brought me to the Shark Lab.
14:00That's what makes me enjoy waking up every day and doing this job.
14:04The Bimini Shark Lab started in 1990.
14:07Right now, at the Shark Lab, we're studying everything from southern stingrays
14:11to bull sharks, tiger sharks, lemon sharks, hammerheads.
14:14But we take it from a very ecosystem-driven model,
14:19where we want to understand everything that's going on around Bimini
14:22and how that's impacting these big sharks.
14:29One of the biggest and most impressive species,
14:32and the focus for a number of Shark Lab's studies,
14:35can be found a stone's throw from the heart of a busy marina.
14:45These are bull sharks,
14:49drawn in by the scraps discarded from fishing boats.
14:55They spend much of their lives in murky estuaries,
15:00so this clear water gives me a unique opportunity to see them up close,
15:05and Matt a chance to learn more about this little-understood species of shark.
15:14I'm here on the bottom of the harbor,
15:17and as you can probably see,
15:19I'm absolutely surrounded by bull sharks.
15:28This is an opportunist that has a very wide array of different kinds of prey.
15:35So they'll feed on fish, on rays, on birds at the surface, on dolphins.
15:41They'll even bite through the shells of turtles.
15:45Now, all the sharks that I'm seeing around me at the moment are females.
15:50I haven't seen a single male.
15:53And they're quite big in the belly.
15:59Why the warm waters of the Bahamas attract these large, slightly rotund females has long been a mystery.
16:07One Matt and his team from Shark Lab are hoping to solve.
16:11But to do that, they first have to catch one.
16:16To go ahead and catch, say, a big female bull shark, what we'll do is drop a baited hook,
16:22throw it right in, and they pretty quickly will normally take the hook.
16:31All right, on, on, on.
16:33Hooking the bull shark is the easy part.
16:35As soon as they start running around with the balls and the rope, this is a bit of a dance
16:41between the person bringing it in and the shark.
16:55We have to be very careful because they are not expecting to be caught and handled by humans.
17:03In order to help, number one, for human safety, but also for shark safety, we'll put a tail rope on.
17:09That helps to secure the shark to the boat.
17:15That's fine, clean it, right in.
17:18With the shark safely harnessed and calm, the team can take measurements and assess the shark's condition.
17:27And one of the most crucial jobs is to find out her reproductive state, using a very familiar method.
17:38Ultrasound.
17:42So I think there's something right there.
17:48So you can see it moving slightly there. That looks like the pup.
17:56Over 50% of the females that we catch are actually pregnant.
18:01They have paired uterus.
18:03So we check both sides, and we're going to try to count the number of pups that we can see,
18:08the size of pups, and both sides to get a better understanding of her offspring litter.
18:14After 10 months, bull sharks give birth to up to 13 pups.
18:20These fully formed, pint-sized sharks are then left to fend for themselves.
18:29Now that we've confirmed she's pregnant, we're going to go ahead and let her go on her way.
18:33Give her a push.
18:36All right, nice job.
18:40At the end of the procedure, it's great to be able to give that shark a push.
18:44We're blessed here with beautiful, clear water, and we can always observe the shark, basically follow her to make sure
18:49that she's swimming strong and that she's doing well.
18:53And it's not just the visiting bull sharks who are carrying the next generation.
19:03Many other species found in the Bahamas are also pregnant.
19:12It's thought that the warm waters and rich feeding grounds here help raise the shark's metabolism and speed up gestation.
19:30We know a lot about sharks, but there's so much more that we still need to understand.
19:35We still don't even know some of the basic reproductive biology, some of their life history things, and these are
19:40all very important for conservation.
19:42I mean, this is what really is going to help us manage the next generation of sharks.
19:49And it's managing this next generation and the habitats that are essential to their survival that's vital to maintaining a
19:56healthy population of sharks.
20:14This tangled mass of roots is the mangroves.
20:18It's an environment that changes constantly with the tides throughout the day and provides the perfect spot for baby marine
20:27animals to hide out in.
20:30I'm joining Clemency White from Bimini Shark Lab to see how these mangroves are key to the success of sharks
20:37in the Bahamas.
20:42Whoa, look at that!
20:45Yep, they're all waiting for us.
20:47Baby sharks!
20:50That's absolutely incredible.
20:58These are lemon sharks, and they've been studied by Clemency and her fellow researchers for over 30 years.
21:06It looks like they want to be fed.
21:09Yep, we actually have a little bit of squid if you wanted to give it a go.
21:11I would genuinely love to.
21:17So, Clemency, how old are the sharks we're looking at here?
21:20So, most of these sharks are in their first few years of life.
21:22So, the majority of them will be maybe two or three years old, and some of those larger sharks you
21:26can see are maybe four or five.
21:28So, this is a refuge.
21:29This is an area that's pretty much only accessible to these guys at high tide.
21:33So, that small narrow walkway that we walked in, bigger sharks can't use that.
21:37What sort of things are they taking shelter from?
21:39The biggest predator of juvenile lemon sharks is actually lemon sharks themselves, adult lemon sharks.
21:43So, they're cannibalistic?
21:44Yes, they are cannibalistic.
21:46And also other large sharks, so maybe bull sharks, other species like that.
21:52So, this genuinely is a nursery.
21:54It's a place where the youngsters are safe from other...
21:58That went right between my legs!
22:00I should be wearing a cricket box or something.
22:04You're okay.
22:05No!
22:07Seriously, they're all just making a beeline straight between my legs!
22:12This would be a disaster if all the things I've done in my life and I was to get savaged
22:16in the ghoulies by a baby shark.
22:18Well, they must like you.
22:21That one there is a decent size.
22:23Yeah, so they'll be pretty loyal to the mangroves that they were born in until they're about 13 years old
22:27when they're sexually mature.
22:29And then they'll also come back to give birth here as adults.
22:31So, they really rely on those mangroves for their entire life cycle.
22:34What are the main threats to mangroves in the Bahamas?
22:37So, a lot of places, even in Bimini, we see the mangroves are being removed to facilitate bigger hotels and
22:43bigger resorts, and that in itself means that these pups will still be born in the same place, they'll still
22:47be used in the same areas, but they won't have that same security from the larger fish.
22:51So, you lose the mangroves and you lose the lemon sharks.
22:55Yep.
22:58It may not look like any other nursery you've seen before, but you can see how vital this environment is
23:05to these rather wonderful and surprisingly cute animals.
23:17All over the world, baby sharks and rays seek refuge in mangroves, seagrass and estuaries.
23:30Throughout their lives, sharks need a whole variety of ocean habitats.
23:37And protecting these is essential if shark numbers are to bounce back.
23:54Most sharks take many years to reach sexual maturity.
23:59female great white sharks need a whopping 33 years before they can breed.
24:07This, combined with their tendency to produce just a few offspring, means that shark populations are extremely vulnerable to overfishing.
24:35And they stand out of coronation, as they let them know if they are contingent.
24:39Right now, sharks are being killed at a staggering rate.
24:45.
24:54They're deliberately caught for food.
24:56They're deliberately caught for food.
24:56.
24:58and accidentally caught in nets or long lines set for other species.
25:09They're also harvested in their millions for their fins,
25:14to make shark fin soup,
25:17a delicacy that's seen shark fins sell for $650 a kilo.
25:28..fuelling a cruel, wasteful trade,
25:31which sees the rest of the shark being thrown back into the sea,
25:37often still alive.
25:42A third of all shark species are now threatened with extinction.
25:48And this is being driven by human activities.
26:08But all is not yet lost.
26:10There is hope.
26:12And it comes from the fact that these sharks
26:15can be worth more alive than dead.
26:33I'm heading 12 miles north of Grand Bahama,
26:37to a site of global importance.
26:50This could well be the best shark dive in the whole world.
26:55And what happens here is key to securing the future of sharks
27:00right across the world.
27:04Whoa! Great hammerhead!
27:06Amazing!
27:08Amazing!
27:09Look at that! Powering straight in!
27:13That is just extraordinary!
27:17Drawn to the warm, productive waters,
27:20this is also the best place in the world to see tiger sharks.
27:28A tiger shark is unmistakable in form.
27:32It has the dappling running down its sides,
27:36which gives it its tiger name.
27:40They'll feed on just about anything they can find in the water.
27:43And with those teeth,
27:45they can even go through the shell of a turtle.
27:50This is absolutely dazzling.
27:54I don't know which way to look.
27:56Tiger sharks, great hammerheads,
27:58lemons, bull sharks, reese sharks.
28:03It's the world's greatest safari.
28:06It just all happens underwater.
28:10Here and throughout the Bahamas, sharks are drawn in with food so tourists can reliably get close to them.
28:22The feeding of sharks is a hotly debated topic.
28:27There's people who think that it's a bad idea and might potentially change the behavior of sharks.
28:34And I can totally see that.
28:36But there's no doubt that shark tourism here in the Bahamas is incredibly important.
28:44Each year, 20,000 people come to the Bahamas to dive with sharks,
28:49making it the largest shark diving industry in the world.
28:55Shark diving here in the Bahamas is worth an estimated $114 million every year to the local economy.
29:07Unquestionably, the sharks are worth more alive than they are dead.
29:13And that's hugely important for the survival of these extraordinary animals.
29:25Okay, set, set, set, set, set, set, set, set, set, set, set, set, set, set, set, set, set, set.
29:38All across the world, shark tourism is fast becoming a thriving industry.
29:43Not just for dive operators, but boat drivers, hotels, restaurants,
29:49and bringing much-needed income to shark hotspots from all over the world.
29:57I came from Philadelphia today to swim with sharks, and it is just invigorating.
30:03It's a whole other world down there.
30:10I'm from Argentina, so it was a long free, but it's amazing.
30:18It's estimated that well over half a million people come to watch sharks every year.
30:24Not only are sharks gaining more advocates, but they now hold an indisputable monetary value.
30:34And this will certainly help to secure their future.
30:44Shark conservation is something that will require human effort for many years to come.
30:49And right here in the Bahamas, there's a very special project that's training up the next generation of shark champions.
31:01Marine biologist Jillian Morris has set up Sharks for Kids.
31:10A charity to show children across the Bahamas that sharks are something to celebrate, not to fear.
31:18I really believe that the best way to change the way people see sharks is to let them get in
31:25the water.
31:30We take kids out to see sharks, and a lot of them are very afraid.
31:34They don't want to get off the boat, they don't want to step off the beach.
31:37And we get them to put a mask and a snorkel on, and we kind of ease them in.
31:42And then they're snorkeling around, and they're seeing the sharks and the rays up close,
31:46and realizing they're not trying to attack them, but they're actually really beautiful animals.
32:03It's really incredible to see students go from being terrified and not wanting to get in the water,
32:07to we're having to drag them out.
32:09We've got to go, it's time to go home.
32:11And to see that transition happen right in front of you, very quickly, is really, really powerful.
32:19The Bahamas is a shark sanctuary, which is incredible,
32:23and has set a standard around the world for shark conservation, shark diving, shark science.
32:28And so it's vital to have the locals involved at all levels, from kids to adults,
32:34to protect the future of this sanctuary and the sharks here in the Bahamas.
32:49While places like the Bahamas offer protection when the sharks are here,
32:55once beyond the invisible boundary of the sanctuary, sharks are immediately vulnerable.
33:04Knowing where they go in this vast, featureless landscape is essential if we're to offer them protection.
33:14A few miles off the coast of Andros, the endless blue is interrupted by a naval buoy.
33:30This lone beacon is a big draw for passing travellers,
33:37providing shelter for schools of fish, which attract the hunters.
33:45The top of the food chain out here are these, silky sharks.
33:52They get their name from the silky sheen of their skin.
34:01So little is known about the migrations of these open ocean drifters.
34:09When shark biologist Tristan Gutteridge heard rumours of this location,
34:15it was an opportunity for him to try and uncover these secrets,
34:19which might just help protect these threatened sharks.
34:27There's nothing that gives me more energy than being in the water with sharks.
34:37These silky sharks, they're a completely different type of animal.
34:43There's just something about them that, you know, brings them closer in and draws them into you.
34:51They have this curious, bold personality, and it is a bit intoxicating, and I love it.
34:59But this inquisitiveness is this shark's Achilles' heel.
35:05Silkies are in trouble globally.
35:08And in fact, silky sharks are the second highest caught shark species in the world.
35:15Industrial fishing often uses floating objects working just like the naval buoy
35:20to attract and aggregate fish like tuna in the open ocean.
35:27But they don't just attract tuna.
35:31Every year, hundreds of thousands of silky sharks get accidentally caught.
35:38I see the evidence of the pressures that these animals are under,
35:42from the hooks in the mouths and the leader wire that's coming out of it.
35:46You can see these sharks, they're in trouble.
35:49They've got a lot to deal with out in the open ocean.
35:54Tristan wants to catch a shark in order to attach a tracker,
35:58which will reveal for the first time where these curious sharks go.
36:06One method that we can use to catch silkies is that you can actually bend the top of the tail
36:12over,
36:13and it sends them into this kind of bizarre, trance-like state.
36:17And if you turn them upside down at the same time, then they're almost playing dead.
36:22They're just out.
36:24It's not fully understood why, but many shark species enter this trance-like state,
36:29called tonic immobility, when upside down,
36:32enabling the team to tether the shark next to the boat.
36:42A satellite tag is fixed to its dorsal fin.
36:46Every five minutes, this tag will record important information,
36:50including depth, light level and water temperature.
36:58After 30 days, it'll pop to the surface
37:01and start sending a stream of data to Tristan.
37:06There's nothing more exciting than in the few days
37:09when you know a tag is going to pop as to where it's going to pop.
37:13It's very important that we learn more about their migration patterns,
37:18their population structure, in order to try and put management measures in place
37:22to improve their conservation.
37:27They deserve to be on this planet, like us, and like anything.
37:32They deserve to be here, and we, as humans, should be responsible.
37:37So it is critical that we learn more about these animals,
37:41and it's critical that we protect them.
37:47Tristan's tags have shown that these sharks not only traverse oceans,
37:52but dive down to feed at depths of over 400 metres,
37:58showing that if we want to protect sharks,
38:01we need to look after every part of our oceans.
38:13Satellite tags are now being deployed on many different species of sharks,
38:17and they're revealing some incredible journeys.
38:23The greatest distance ever recorded was by a great white shark named Nicole,
38:29who swam from South Africa to Australia,
38:32and back again, a staggering 12,000 miles in just nine months.
38:48While understanding where these top predators go is important,
38:52another vital piece of this conservation puzzle is understanding why they go.
39:07Just off the coast of Bimini in the Bahamas,
39:10there's a dive site that, for a few months each year,
39:14provides a close encounter with one of our most iconic and well-known migratory sharks.
39:24This is the only place in the whole world where you can reliably see great hammerhead sharks.
39:33So we have dozens of sharks around us.
39:35Most are like this one here.
39:38It's a nurse shark.
39:41And the reason they have this name is that when they're feeding,
39:44they make a sucking noise.
39:47Kind of like a baby when it's nursing, when it's feeding.
39:52You can see that they're quite content lying on the bottom.
39:55They can pump water through their gills,
39:59and they don't have to swim constantly in order to breathe like many other sharks do.
40:06But this creature that's heading towards us now,
40:11that really is the main event.
40:13It's a great hammerhead.
40:16There are at least three of them around us right now.
40:22And while the nurse sharks are quite dopey and just hang out on the bottom,
40:28this is a far more targeted predator.
40:32There is nothing else quite like the great hammerhead shark.
40:35The shape of the head, the giant dorsal fin.
40:40It's so unusual looking.
40:43And yet, so perfectly adapted to its job.
40:48Shaking the hammerhead from side to side as it moves along the bottom.
40:52Sensing the potential moving muscles of its prey.
41:01Perhaps the most incredible thing about this is that great hammerheads are an endangered species.
41:10There are very, very few of these almighty sharks left in the whole world.
41:16And right now, I think we have seven.
41:21I don't quite know what to say. I'm completely blown away.
41:32These great hammerheads are seasonal visitors, spending the winter months here between December and April.
41:42Many return year after year.
41:49The scientists have at least 30 individuals that they know by name.
41:55And not just by name, but by personality and character and behaviour.
42:02And even in the short time since I've been here, I've been starting to get to know the individual personalities
42:09here.
42:10You might not think of a shark as having a personality, but they very much do.
42:15Some of them are quite bold and dramatic and others are real gentle giants.
42:24This almighty grey hammerhead here is called Gaia.
42:29She's a female and the largest that they see here.
42:36What an absolute beauty!
42:43I will never, ever get tired of this!
42:47Shhh!
42:49Holy moly!
42:51Ha ha ha ha ha!
42:55For five months of the year, these hammerheads are seen virtually every day.
43:01But in April, they suddenly disappear.
43:16One female was tagged here at Bimini.
43:19She then headed north to the coast of the Carolinas, before turning south again, ending up off the coast of
43:26Florida.
43:27A journey of over 3,000 miles in less than two months.
43:39But what's causing these ocean wanderers to travel so far and so fast?
43:51I'm taking to the air to find out.
44:01This is Palm Beach, Florida.
44:04It's a playground for the rich and the famous.
44:07But little do they know that just off the coast is one of the greatest gatherings of large predators on
44:13the planet.
44:22These are blacktip sharks.
44:31Massing in their thousands before migrating north to their summer feeding grounds off the coast of North Carolina.
44:40It's these sharks that attract a host of larger predatory sharks, including the Great Hammerheads, which travel from the Bahamas
44:48to feast on this bounty of food.
44:54I joined Stephen Kudura, a professor at Florida Atlantic University.
45:00Each year, he takes to the air to monitor the number of sharks.
45:07Just a slick of sharks going on all the way parallel to the coast.
45:13That is absolutely fantastic.
45:16They stand out so well against the sandy bottom, don't they?
45:20That's one of the reasons we're so successful with the aerial surveys here.
45:23We have clear water, a light sandy bottom, you're able to see everything.
45:27And they're in nice and shallow.
45:28They really make it easy for you, don't they?
45:32But all's not what it seems.
45:35Stephen's long-term study has shown that this spectacular migration is changing.
45:41And this could have serious consequences.
45:44I've been doing these aerial surveys for the last nine years.
45:48And we've seen this decline in the number of sharks over the past nine years.
45:52At the same time, we've seen an increase in the water temperature down here.
45:56They have a very narrow thermal tolerance.
45:58They like water between about 21 to 25 Celsius.
46:01And as water temperatures keep rising, we're getting fewer and fewer sharks coming this far south.
46:07Presumably, the blacktips that you've got here, there are constant interactions between them and the larger predatory sharks like the
46:13tigers, the great hammerheads, and the bulls.
46:15How is that likely to be affected?
46:17That's a really good question.
46:18If you don't have these blacktips sweeping down here in the tens of thousands every spring, there's no food for
46:25the big hammerheads.
46:25And these blacktips are not eating all the bait fish.
46:28And so we don't even know what might happen.
46:36You know, these ecosystems have remained pretty much unchanged for millennia.
46:40But they are dramatically changing in my lifetime.
46:43And where that will lead, we simply don't know.
46:53The rate at which our seas are heating up is accelerating.
46:58And the effects of this warming are now being felt in every one of our oceans.
47:17Sharks are under pressure from all sides.
47:20Fishing, their habitats changing, and now in these protected waters, their fellow sea creatures.
47:34Recently, an unwanted visitor has appeared in Caribbean waters.
47:46This is a lionfish.
47:51A predator that could eat fish populations out of existence.
47:58Threatening the future of the resident sharks.
48:07Ten years ago, I saw for myself just what devastating predators they are in their native waters off Malaysia.
48:16There's a small fish over here.
48:19The lionfish has spotted it.
48:22This could be trouble.
48:25It's moving in.
48:29Oh, unbelievable!
48:31Did you see the speed of that strike?
48:36Lionfish eat about 70 different species of fish and invertebrates.
48:44If it fits in their mouth, they'll eat it.
48:47If it fits in their mouth, they'll eat it.
48:52You did it again!
48:56This is just the most astounding display of feeding I think I've never seen!
49:09Such an elegant fish is unsurprisingly a favourite of the aquarium trade.
49:15And in the 1980s, a few unwanted pets ended up being released in the seas off Florida.
49:24With devastating results.
49:31In just over 30 years, they've spread from coastal Florida with alarming speed.
49:38They're now found as far north as New York, and south to Brazil.
49:45This is the wrong fish, in the wrong place, and at the wrong time.
49:53And it's threatening to unbalance the already fragile system upon which the sharks depend.
50:03This is a growing problem that people like marine biologist Alex Fogg are trying to find a solution to.
50:11The reefs have changed actually quite a bit since I first started diving.
50:14I started diving about 10 years ago.
50:16And in this area in particular, lionfish weren't here yet.
50:26When we first started seeing lionfish on the reef, it was one here, one there.
50:30But now you go to a reef site and you can see upwards of 100 lionfish.
50:34I mean, they're here eating everything.
50:36It's like an all-you-can-eat buffet, if you will.
50:41They're not just voracious hunters, they're prolific breeders too.
50:46A female lionfish can lay more than 20,000 eggs every four days.
50:55They can reach densities of over 200 adults per acre of reef.
50:59And that quantity can hoover up nearly half a million fish a year.
51:08This is having a devastating effect on an already fragile ecosystem.
51:13But Alex has a plan.
51:20You can't really catch them on hook and line.
51:22There's really only one way to harvest lionfish and that's through diving and harvesting with spears.
51:32And all these fish don't go to waste.
51:38Lionfish are definitely one of the most environmentally friendly fish that you can actually eat.
51:44This is one fish that we want to eat into extinction.
51:48Hey chef, got you a bunch of fish.
51:49All right man, appreciate it. Thank you very much.
51:58Alex hopes that by making a commercial market for these lionfish, more will be caught.
52:04Allowing reefs and sharks to recover.
52:10Ten years down the road from now, lionfish are still going to be here.
52:14Are they going to be at the numbers that we have today? I'm not sure.
52:17I think that if we can just get lionfish to a point to where the ecosystem can actually deal with
52:22it,
52:22or they find their space in the ecosystem, that's our best bet.
52:28The market for lionfish and restaurants is growing.
52:32But to fully combat this invasion, things have been taken a step further.
52:45Along the coast of America, locals have created lionfish derbies.
52:52The aim, to collect and remove as many lionfish as possible.
53:06Each fish is measured and prizes are awarded for catching the most, the biggest and the smallest lionfish.
53:26Hundreds gather to share in the fries and eat the catch.
53:41These derbies serve to reduce numbers, as well as raising awareness of a fish that threatens the ocean ecosystems upon
53:50which the sharks rely.
54:07Our blue planet is defined by its oceans.
54:14And if they're to stay healthy and productive, we need a healthy population of sharks.
54:24At present, sharks are being killed faster than they can reproduce.
54:29And we're set to lose some of our most iconic species in the next 50 years.
54:41But across the globe, many people are working tirelessly to uncover the secrets of sharks in order to save them.
54:52People are seeing sharks in their true light.
54:56And starting to appreciate them for the essential role they play in our oceans.
55:05There is still much work that needs to be done.
55:10But for now, there is hope.
55:13For our oceans are packed with the ingredients for recovery.
55:22The seas are full of tiny, microscopic life, just looking for somewhere to fix and make home.
55:37This is the Sapona.
55:43It was grounded here in a hurricane many decades ago.
55:48And ever since, it's become a living reef.
55:54Absolutely bursting with life.
56:00So many fish.
56:04So beautiful.
56:11The superstructure makes a perfect habitat.
56:16Places for them to hide from predators.
56:19And it's covered with encrusting soft corals and fans.
56:29All sorts of animals take up shelter inside.
56:38Oh, stingray.
56:43It's like swimming through the rib cage.
56:48Of an almighty whale lying on the bottom.
56:52Incredible.
56:59This is the basis of the food chain upon which sharks depend.
57:14If we protect our seas and life will bounce back in our oceans.
57:19If we give it the chance.
57:27The interconnectedness of our oceans and their inhabitants is intricate and far reaching.
57:35Sharks depend on the creatures around them.
57:38As these creatures in turn depend on the sharks.
57:43They've been stalking our seas for at least 400 million years.
57:48I hope they've got a few million more left in them yet.
57:54The Bahamas are at the forefront of shark research and conservation.
58:00And lessons learnt here now need to be applied all across our blue planet.
58:10The future of sharks is in our hands.
58:15And it's for us to decide where this shark's tail goes next.
58:36And it's for us to decide where this shark's tail goes next.
58:43And we'll have that covered with a story of one of the last great adventurers.
58:47The Odyssey at 10.