0:00:28 > 0:00:31The first time I saw a manta it took my breath away.
0:00:33 > 0:00:38It just came out of the gloom right towards me and it was like
0:00:38 > 0:00:40the most beautiful underwater bird I'd ever seen.
0:00:43 > 0:00:45It was so majestic
0:00:45 > 0:00:51and I couldn't even focus on anything except this magnificent animal.
0:00:57 > 0:01:02This chance meeting changed the course of Andrea Marshall's life.
0:01:02 > 0:01:07Manta rays are unlike anything I've ever been in the water with.
0:01:07 > 0:01:09They're inquisitive, they will engage a diver.
0:01:09 > 0:01:12It's just an amazing experience to be with them
0:01:12 > 0:01:17because you can actually see that they want to interact with you, and they are quite curious.
0:01:18 > 0:01:20And it was a brief encounter,
0:01:20 > 0:01:24but at the same time I knew then that I would never be the same again.
0:01:26 > 0:01:31Abandoning her life in California, the young biologist moved to Africa
0:01:31 > 0:01:33for a life with manta rays.
0:01:35 > 0:01:36Her dream -
0:01:36 > 0:01:40to find out all there is to know about these mysterious creatures.
0:01:44 > 0:01:50And seven years on, her work has rocked the world of science
0:01:50 > 0:01:53with the discovery of a new species of giant manta
0:01:53 > 0:01:58and remarkable new findings about how they live their lives.
0:02:01 > 0:02:07But around the world, mantas are in trouble - their numbers crashing.
0:02:08 > 0:02:13It is terribly frightening that something as beautiful and as important as a manta ray
0:02:13 > 0:02:16could ever be brought to the brink of extinction.
0:02:17 > 0:02:21From fighting to protect these beautiful rays
0:02:21 > 0:02:26to ground-breaking revelations about their secretive lives,
0:02:26 > 0:02:32this film charts a remarkable year of Andrea's life living with mantas.
0:02:53 > 0:02:56Tofo Beach, Mozambique,
0:02:56 > 0:02:59where the Indian Ocean meets the east coast of Africa.
0:03:02 > 0:03:07And it's here, on this wild, inaccessible stretch of coast,
0:03:07 > 0:03:09that Andrea lives and works.
0:03:14 > 0:03:18Look at him! Too cool!
0:03:18 > 0:03:21We've motored about five miles down the coast
0:03:21 > 0:03:23to dive at one of the many inshore reefs off here.
0:03:23 > 0:03:30The place we're going today is called Manta Reef and it's a renowned cleaning station for manta rays.
0:03:31 > 0:03:34Every day, Andrea makes the ten-mile round trip
0:03:34 > 0:03:37to one of the many reefs that are scattered amongst these waters.
0:03:38 > 0:03:41I think we should dive the south side of the reef today.
0:03:41 > 0:03:44So about another 400 metres, and slightly to the left would be good.
0:03:44 > 0:03:48And it's amongst these newly discovered reefs that Andrea has
0:03:48 > 0:03:53found one of the largest populations of manta rays in the world.
0:04:03 > 0:04:08Do me a favour, if you see any pregnant ones down there, just keep a track of how many that you see.
0:04:08 > 0:04:10We'll be about 40 minutes, OK?
0:04:25 > 0:04:29Several major currents converge at Tofo,
0:04:29 > 0:04:32creating some of the richest waters on the African coast.
0:04:35 > 0:04:39I hadn't actually seen anything quite like the Mozambique coastline
0:04:39 > 0:04:40when I first came here.
0:04:40 > 0:04:42There was just so much life here.
0:04:42 > 0:04:45It was like the Galapagos of the Indian Ocean.
0:04:45 > 0:04:49There's so much plankton, it turns the waters cloudy
0:04:49 > 0:04:54drawing in leviathans from across the Indian Ocean to feed.
0:05:04 > 0:05:07And it's here, living amongst these reefs,
0:05:07 > 0:05:11that Andrea has discovered more than 650 manta rays.
0:05:23 > 0:05:26With a wingspan of up to seven-and-a-half metres,
0:05:26 > 0:05:29mantas are the largest of all the rays.
0:05:32 > 0:05:38Once feared as dangerous devil fish, they're in fact harmless giants,
0:05:38 > 0:05:41feeding only on the tiny plants and animals that make up the plankton.
0:05:45 > 0:05:46Yet intriguingly,
0:05:46 > 0:05:51mantas could be one of the most intelligent creatures in the ocean.
0:05:51 > 0:05:55For their size, they have the largest brain of any fish,
0:05:55 > 0:05:57and no-one knows why.
0:06:00 > 0:06:03They almost have personalities.
0:06:03 > 0:06:07Some of them are more shy, some of them are more bold.
0:06:07 > 0:06:11Some of them love bubbles on their tummies, some of them don't.
0:06:11 > 0:06:15They don't swim away from you like a normal shark or fish would.
0:06:15 > 0:06:16So they really engage you,
0:06:16 > 0:06:19and it makes working on them all the more fun.
0:06:19 > 0:06:21And that's a great feeling as a biologist
0:06:21 > 0:06:24to actually have a connection with the animal you're working with.
0:06:26 > 0:06:28Despite their size and curious nature,
0:06:28 > 0:06:31very little is known about manta rays.
0:06:36 > 0:06:41So armed with her camera, Andrea records every move they make.
0:06:42 > 0:06:46With each dive, she's discovering more and more about them.
0:06:46 > 0:06:50Building up an intimate picture of their secretive lives.
0:06:59 > 0:07:01Did you see Jo? She was one of the pregnant ones.
0:07:01 > 0:07:06That's the second year I've seen her consecutively pregnant. That's amazing.
0:07:08 > 0:07:11We saw a number of individuals, maybe about ten.
0:07:11 > 0:07:14A lot of ones that I knew, a couple of ones that I didn't know,
0:07:14 > 0:07:18a lot of ID shots, so there should be a lot of information there,
0:07:18 > 0:07:20a few pregnant ones.
0:07:20 > 0:07:24So that's a good sign. That's exactly what we want to see.
0:07:33 > 0:07:39From this straw hut, Andrea runs the Mozambican Manta Ray Project.
0:07:39 > 0:07:42And with the support of the Save Our Seas foundation,
0:07:42 > 0:07:45she's transforming this remote site on Tofo Beach
0:07:45 > 0:07:49into one of the leading research centres in the Indian Ocean.
0:07:51 > 0:07:54At the moment I'm actually uploading my photos from today's dive
0:07:54 > 0:07:58just to check the individuals I saw on the reef today.
0:07:58 > 0:08:04Like a fingerprint, every manta's born with a unique spot pattern on its belly.
0:08:04 > 0:08:06And it's the shape of these spots
0:08:06 > 0:08:11that gives Andrea the inspiration for naming her mantas.
0:08:11 > 0:08:12I try and see an image.
0:08:12 > 0:08:15So I basically have named all 650 mantas
0:08:15 > 0:08:17after something that pops out at me.
0:08:17 > 0:08:20So I have names ranging from cartoon characters,
0:08:20 > 0:08:22all the way to presidents.
0:08:22 > 0:08:28Andrea calls the two new arrivals Spotty and Bleeding Heart.
0:08:28 > 0:08:34And they join the likes of Homer Simpson and Dracula on her growing database.
0:08:34 > 0:08:39What's important is not the name, but the fact that when I'm on the reef I know all the different individuals
0:08:39 > 0:08:43I'm seeing, and the picture becomes so much more clear.
0:08:43 > 0:08:45It's a more intimate type of research
0:08:45 > 0:08:49and it's quite exciting because they are kind of like my little children.
0:08:50 > 0:08:54And after thousands of dives with Mozambique's mantas,
0:08:54 > 0:08:57Andrea's beginning to understand their lives.
0:08:58 > 0:09:03She's found that many of them are resident to these waters.
0:09:03 > 0:09:08But what surprised her the most was that 80% of the mantas were female.
0:09:11 > 0:09:15I really strongly believe this is one of the most important sites,
0:09:15 > 0:09:17a critical habitat for manta rays.
0:09:17 > 0:09:19They are coming here to mate,
0:09:19 > 0:09:23the females are hanging around for most of the year to give birth,
0:09:23 > 0:09:25find mates and have their pups
0:09:25 > 0:09:30which is probably why they occur in such large numbers.
0:09:37 > 0:09:44By sheer luck Andrea had not only discovered one of the largest populations of mantas in the world,
0:09:44 > 0:09:47but she'd stumbled across a manta breeding site.
0:09:49 > 0:09:52There's nowhere else like it in the world.
0:10:04 > 0:10:08But living in such a remote corner of Africa has been far from easy.
0:10:12 > 0:10:16'It was very intimidating when I first moved to Mozambique.
0:10:16 > 0:10:19'I actually didn't know anyone when I first came here.'
0:10:19 > 0:10:21I try and act tough sometimes,
0:10:21 > 0:10:24but I am a girl that came from a sheltered environment.
0:10:24 > 0:10:27I grew up in California with a lot of close friends and family
0:10:27 > 0:10:30and it was tough for the first few years.
0:10:30 > 0:10:35'But at the same time, I knew it was going to be well worth the effort that was put in.'
0:10:37 > 0:10:39I get a bit nervous driving around here,
0:10:39 > 0:10:41because people hit a lot of people on these roads.
0:10:41 > 0:10:44These roads are terrible.
0:10:45 > 0:10:47What are you doing?
0:10:47 > 0:10:49CAR HORN TOOTS
0:10:51 > 0:10:54Speaking of why it is dangerous to live in Africa!
0:11:02 > 0:11:06It's November and the manta breeding season has begun.
0:11:09 > 0:11:11It's a key time for Andrea
0:11:11 > 0:11:15and dive buddy and research partner, Simon Pierce,
0:11:15 > 0:11:18but it's going to be a dangerous launch.
0:11:20 > 0:11:25Conditions are pretty miserable today. There's huge swells.
0:11:25 > 0:11:27Short distance between the waves.
0:11:27 > 0:11:29It's not ideal at all.
0:11:29 > 0:11:31It's actually quite dangerous.
0:11:31 > 0:11:34People have flipped boats here before.
0:11:34 > 0:11:37People have lost people over the side of boats.
0:11:37 > 0:11:39But, you know, it's the only way we can get out.
0:11:49 > 0:11:54With waves of up to three metres, no coastguard,
0:11:54 > 0:11:56and the nearest doctor 30 miles away
0:11:56 > 0:11:58there's no room for error.
0:12:15 > 0:12:17You know you've got to get out.
0:12:17 > 0:12:20I mean, there's no harbours to launch from here,
0:12:20 > 0:12:23and so basically if I don't get out, I don't get to do my research.
0:12:23 > 0:12:26SHE WHOOPS
0:12:34 > 0:12:38Today Andrea is setting up a state of the art acoustic tagging study.
0:12:38 > 0:12:42It will record what her reef mantas do when she's not around.
0:12:46 > 0:12:47But to get the project started,
0:12:47 > 0:12:50she's got to be good with a spear gun.
0:12:51 > 0:12:53My shot's pretty good, you know.
0:12:53 > 0:12:55We pick a place on the manta to shoot,
0:12:55 > 0:12:58and I'm usually within a couple of inches of that shot,
0:12:58 > 0:13:02so, I think I'm all right at least on my shot. Just not on loading.
0:13:02 > 0:13:05Well, it helps that she's only about that far away!
0:13:16 > 0:13:19As they make their way down to Manta Reef,
0:13:19 > 0:13:23Andrea spots one of the ocean's rarest creatures.
0:13:32 > 0:13:35It's a small-eyed stingray.
0:13:39 > 0:13:43Tofo is the only place in the world where they've ever been seen alive.
0:13:50 > 0:13:52At more than two-and-a-half metres across,
0:13:52 > 0:13:54it's the largest of the stingrays.
0:13:59 > 0:14:01And this brief encounter
0:14:01 > 0:14:04is the first footage ever to be shown of them.
0:14:13 > 0:14:14As the ray moves off,
0:14:14 > 0:14:18Andrea and Simon set to work anchoring a special "listening post"
0:14:18 > 0:14:20to the sea bed.
0:14:22 > 0:14:26For the next 12 months, it will monitor the mantas'
0:14:26 > 0:14:28day-to-day movements around the reef.
0:14:32 > 0:14:37A manta Andrea's known for four years, called Tri-Star,
0:14:37 > 0:14:41is the first to get a tiny acoustic transmitter attached to her back.
0:14:46 > 0:14:49She's now emitting her very own signature tune.
0:14:49 > 0:14:52FAINT BEEPING
0:14:54 > 0:14:59Whenever Tri-Star comes within 400 metres of the listening post,
0:14:59 > 0:15:04it will detect her signal, logging her in and out of the reef.
0:15:15 > 0:15:18Got a tag on Tri-Star, which is one of my favourites...
0:15:18 > 0:15:21I've known her since 2004, so that was really exciting.
0:15:21 > 0:15:24And she was pregnant again so that was fantastic.
0:15:24 > 0:15:29I'll just go back and see what kind of data we can get from her in a few months.
0:15:29 > 0:15:35Over the coming days, five more reef mantas will be tagged.
0:15:35 > 0:15:40These acoustic tags are giving us 24-hour information, 365 days a year.
0:15:40 > 0:15:43So it's really fantastic technology.
0:15:47 > 0:15:48Back underwater,
0:15:48 > 0:15:53the mantas arrive on the reef in ever-increasing numbers.
0:15:57 > 0:16:01During November they gather here to court and mate.
0:16:03 > 0:16:06And the displays can be breathtaking.
0:16:15 > 0:16:18Before Andrea started her work in Mozambique,
0:16:18 > 0:16:21very little was known about manta breeding behaviour.
0:16:23 > 0:16:27A female manta, when she's ready, when she wants to mate,
0:16:27 > 0:16:30she will lead males on almost a chase
0:16:30 > 0:16:33and you usually get a single large female
0:16:33 > 0:16:37followed by what's called a train of many males.
0:16:39 > 0:16:43Sometimes one or two, and sometimes it's 20
0:16:43 > 0:16:47And they will chase her around the reef at high speeds and basically
0:16:47 > 0:16:51everything that she does, the males will actually do behind her.
0:16:51 > 0:16:54It's almost uncanny, so it's beautiful to see.
0:16:55 > 0:16:57If she banks, they bank,
0:16:57 > 0:17:01if she turns, they turn, if she flips, they flip.
0:17:05 > 0:17:08Mantas usually give birth to a single pup
0:17:08 > 0:17:10after a 12-month pregnancy.
0:17:16 > 0:17:18But in another manta first,
0:17:18 > 0:17:22Andrea's found it's very rare for them to pup each year.
0:17:25 > 0:17:27That's one of the very important distinctions
0:17:27 > 0:17:30that I've made here in Mozambique.
0:17:30 > 0:17:34Manta rays often have one or two years off in between pregnancies,
0:17:34 > 0:17:37and that's probably to recoup energy stores.
0:17:39 > 0:17:42So the fact that they only have one pup every two to three years
0:17:42 > 0:17:47is a very, very important in terms of conserving them because it means that they don't have the ability
0:17:47 > 0:17:50to repopulate if they're under threat,
0:17:50 > 0:17:52for instance, from fishing pressure.
0:18:05 > 0:18:08With manta rays reproducing so slowly,
0:18:08 > 0:18:10the only way for Andrea to protect them
0:18:10 > 0:18:13is to make regular visits to the fishing communities
0:18:13 > 0:18:16that line Mozambique's sparsely populated coast.
0:18:20 > 0:18:26I want to know what season the people take and kill the manta rays here, what time of year?
0:18:29 > 0:18:32He says in the summer months when the mantas are at the surface -
0:18:32 > 0:18:36that's their breeding season - they will kill a lot, so that is very disturbing
0:18:36 > 0:18:39and that's probably why they catch a lot of pregnant females.
0:18:40 > 0:18:43The fishermen here are just trying to survive.
0:18:43 > 0:18:46They don't know that these populations are fragile.
0:18:46 > 0:18:51They don't understand that by taking even what seems like a few to them,
0:18:51 > 0:18:53they can have devastating and permanent effects.
0:18:55 > 0:18:58And it's not just mantas that are being hauled in.
0:19:01 > 0:19:04Who do they sell this to?
0:19:04 > 0:19:07HE ASKS QUESTION IN LOCAL DIALECT
0:19:08 > 0:19:11We know that there are Chinese syndicates along this coastline
0:19:11 > 0:19:13that are buying shark fins for a lot of money.
0:19:13 > 0:19:16But they're very secretive about who they're selling to
0:19:16 > 0:19:20and it's no wonder, they make a very good living out of selling shark fins.
0:19:24 > 0:19:30The growing Chinese influence along this coast is a real concern.
0:19:31 > 0:19:35Mantas are highly prized in traditional Chinese medicine.
0:19:35 > 0:19:40And the financial rewards for poor fishing communities like this
0:19:40 > 0:19:42could be hard to resist.
0:19:54 > 0:19:57Throughout the world, in areas where they are fished,
0:19:57 > 0:19:59mantas are listed as vulnerable to extinction.
0:20:04 > 0:20:09The only way for Andrea to give Mozambique's mantas any long-term protection,
0:20:09 > 0:20:11is to get this remote stretch of coast
0:20:11 > 0:20:13recognised as a marine reserve.
0:20:17 > 0:20:20These waters are visited by more whale sharks
0:20:20 > 0:20:22than anywhere else in the world.
0:20:26 > 0:20:30Whales, from humpbacks to southern rights,
0:20:30 > 0:20:32are regularly seen here, too.
0:20:32 > 0:20:34WHALE SONG
0:20:44 > 0:20:47But there's a much rarer creature that comes here,
0:20:47 > 0:20:52a creature that's led to Andrea's most remarkable discovery yet...
0:20:54 > 0:20:56..giants.
0:21:03 > 0:21:06Up to two metres larger than the reef mantas,
0:21:06 > 0:21:10the giants usually stay at Tofo for just few days,
0:21:10 > 0:21:15before disappearing back into the Indian Ocean,
0:21:15 > 0:21:17rarely, if ever, to be seen again.
0:21:21 > 0:21:23Until now,
0:21:23 > 0:21:27it was thought there was just one species of manta in the ocean.
0:21:28 > 0:21:30But the more Andrea swam with them,
0:21:30 > 0:21:33the more she noticed how different they were.
0:21:36 > 0:21:39With a wingspan of up to 7.5 metres,
0:21:39 > 0:21:43they were not only much larger than the reef mantas,
0:21:43 > 0:21:46but their markings were also much more pronounced.
0:21:50 > 0:21:53All these little things started adding up.
0:21:53 > 0:21:55I just had such a hunch.
0:21:55 > 0:22:00I just knew...I just knew in my heart that there was a difference there.
0:22:01 > 0:22:02But she needed proof.
0:22:04 > 0:22:08And it came from a strange bump on the giant's tail.
0:22:13 > 0:22:17When I first saw the tail, my heart was beating so fast, I just...
0:22:17 > 0:22:19It's hard to explain.
0:22:21 > 0:22:25Mantas evolved from stingrays millions of years ago,
0:22:25 > 0:22:29and when they did, it was thought they'd lost their sting.
0:22:30 > 0:22:34But while the smaller mantas had lost theirs,
0:22:34 > 0:22:37Andrea found the giants still had the remains
0:22:37 > 0:22:39of a stinging spine in the bump on their tail.
0:22:40 > 0:22:44So to see mantas, a group of mantas that I knew was different,
0:22:44 > 0:22:47have a spine still, it was amazing to me.
0:22:47 > 0:22:51It was kind of seeing, like, the missing link in evolution.
0:22:53 > 0:22:56It was the proof Andrea had been searching for.
0:22:57 > 0:23:01And finally, she was able to announce to the world
0:23:01 > 0:23:04that she'd found a new, giant species of manta.
0:23:06 > 0:23:09For the then unknown field researcher,
0:23:09 > 0:23:11with little more than a passion for mantas,
0:23:11 > 0:23:14it was an astonishing breakthrough.
0:23:22 > 0:23:27But where the giants go after their brief visit to the Mozambique coast,
0:23:27 > 0:23:30that remains a mystery.
0:23:33 > 0:23:36I have such a hunch that they are long distance swimmers.
0:23:36 > 0:23:38I feel that they are very migratory.
0:23:38 > 0:23:43I feel that they might be actually travelling really long distances.
0:23:43 > 0:23:45If the giants ARE ocean travellers,
0:23:45 > 0:23:48they're likely to be spending much of their lives
0:23:48 > 0:23:51in the heavily fished waters of the Indian Ocean.
0:23:53 > 0:23:56With the giants potentially at great risk,
0:23:56 > 0:24:01for Andrea, the race is on to find out where they go and why.
0:24:05 > 0:24:09Following up on all sightings of giants
0:24:09 > 0:24:12Andrea's heading 3,000 miles across the Indian Ocean
0:24:12 > 0:24:14to the Maldive Islands.
0:24:16 > 0:24:18Here a manta research team
0:24:18 > 0:24:21are reporting occasional sightings of giants.
0:24:21 > 0:24:24As well as huge gatherings of reef mantas...
0:24:35 > 0:24:39With more than 1,200 coral islands scattered across 500 miles of water
0:24:39 > 0:24:42the Maldives have some of the richest reefs in the world.
0:25:05 > 0:25:09- Hi! How are you going?- Good, you? - That was absolutely spectacular.
0:25:09 > 0:25:13Guy Stevens from the Save Our Seas Maldivian Manta Ray Project
0:25:13 > 0:25:16has been studying the mantas here for four years.
0:25:16 > 0:25:19Well, I just got a call from the guys out there,
0:25:19 > 0:25:20and there's about three whale sharks
0:25:20 > 0:25:23- and 100 mantas. - Oh, excellent. That's fantastic.
0:25:23 > 0:25:26- OK? Right... - Well, let's get in the boat.
0:25:26 > 0:25:31The Baa Atoll is a circular chain of 60 tiny islands.
0:25:31 > 0:25:34A network of coral reefs snake between them,
0:25:34 > 0:25:38channelling the fast-moving currents.
0:25:38 > 0:25:39- Look, Andrea, look!- Look at them!
0:25:39 > 0:25:42- Oh, there's one, there's one! - Right here.
0:25:42 > 0:25:44Oh, wow!
0:25:44 > 0:25:47Look at him, wow, there's so many.
0:25:47 > 0:25:49Wow, there's heaps right there, right now.
0:25:49 > 0:25:54Here at Hanifaru, the currents sweep into a horseshoe-shaped lagoon,
0:25:54 > 0:25:56creating the perfect conditions
0:25:56 > 0:25:59for one of nature's most extraordinary events.
0:25:59 > 0:26:02Wow, that is a massive group.
0:26:02 > 0:26:05And you can see right down there.
0:26:05 > 0:26:12- As many as you can see up here, it'll be full way down to the bottom.- That is amazing.
0:26:12 > 0:26:14- Can we get in and start looking? - Yep. Let's go.
0:26:25 > 0:26:27Nowhere else in the world
0:26:27 > 0:26:30do mantas gather together in such huge numbers.
0:26:38 > 0:26:42Within minutes, more than 100 arrive in the lagoon.
0:27:17 > 0:27:20All are reef mantas.
0:27:23 > 0:27:26The giants are nowhere to be seen...
0:27:32 > 0:27:35'I'd never actually been in a situation like that
0:27:35 > 0:27:36'with mantas before.
0:27:38 > 0:27:40'I've never seen so many in one location.
0:27:40 > 0:27:44'I've been diving all over the world with manta rays
0:27:44 > 0:27:46'so it was actually a really extraordinary experience.
0:27:51 > 0:27:56'They were just packed one on top of another - it was madness.
0:27:56 > 0:27:59'I was just blown away, completely blown away.'
0:28:11 > 0:28:15Never filmed before, the mantas only gather on this scale
0:28:15 > 0:28:17for a few days each year.
0:28:21 > 0:28:24And it only happens during the monsoon,
0:28:24 > 0:28:26when spring tides cause strong currents
0:28:26 > 0:28:28to draw up nutrients from the depths.
0:28:33 > 0:28:37It creates the perfect conditions for a plankton explosion.
0:28:40 > 0:28:42And a feast for the mantas.
0:28:52 > 0:28:56This somersaulting, called "barrel-rolling",
0:28:56 > 0:29:00funnels the plankton into their mouths in even greater numbers.
0:29:11 > 0:29:14Then, Andrea spots some of the mantas
0:29:14 > 0:29:16skimming across the lagoon floor.
0:29:16 > 0:29:22Again, it's behaviour that's never been filmed before...
0:29:22 > 0:29:25What they're feeding on is unclear.
0:29:26 > 0:29:30It's likely the plankton, trying to escape the mantas circling above,
0:29:30 > 0:29:33have sunk down and got trapped on the sea bed.
0:29:38 > 0:29:40Intriguingly,
0:29:40 > 0:29:43the mantas have changed the position of their front fins,
0:29:43 > 0:29:45moving them away from their mouths
0:29:45 > 0:29:48to get as close to the sea bed as possible.
0:29:56 > 0:29:59I think that what all the different feeding behaviours tell you
0:29:59 > 0:30:00is that mantas are thinkers, you know!
0:30:03 > 0:30:04When the plankton's diffuse
0:30:04 > 0:30:07they'll obviously swim through the water column with the mouth open,
0:30:07 > 0:30:10but when it's concentrated they do these barrel rolls,
0:30:10 > 0:30:12and when the plankton actually settles onto the ground,
0:30:12 > 0:30:15then they change their feeding strategy entirely
0:30:15 > 0:30:17and actually feed off the ground.
0:30:31 > 0:30:33After more than an hour in the water,
0:30:33 > 0:30:37the tide starts to change, sweeping the plankton bloom away.
0:30:40 > 0:30:44As quickly as they came, the mantas start to disappear.
0:30:52 > 0:30:55Pretty good, eh?
0:30:55 > 0:30:58Oh, wow. That was sensational.
0:30:58 > 0:31:01Have a look at all those mantas.
0:31:03 > 0:31:06That had to have been the best dive I've ever done in my life,
0:31:06 > 0:31:08I really do think.
0:31:08 > 0:31:09I was dancing with them!
0:31:09 > 0:31:12It was just incredible.
0:31:19 > 0:31:22I know I didn't see any of the giants down there today.
0:31:22 > 0:31:25- Did you?- No. Not today. And that's not surprising for me.
0:31:25 > 0:31:27I expect...
0:31:27 > 0:31:29When I see one, it's like, wow.
0:31:29 > 0:31:31It's an event. It's not like a regular thing.
0:31:31 > 0:31:35- Do you ever see them in this area? - Yeah, I've seen about two here.
0:31:35 > 0:31:37And they'll be feeding with the others,
0:31:37 > 0:31:40but they won't ever interact, yeah, associate.
0:31:40 > 0:31:43So if you have a chain of mantas, you'll never get
0:31:43 > 0:31:48the larger species, the giant mantas, interacting with the others.
0:31:50 > 0:31:53As the light begins to fade,
0:31:53 > 0:31:56it's time to make the one-hour journey back to Guy's base.
0:32:00 > 0:32:04But the day's work isn't over yet.
0:32:04 > 0:32:07You can just about make out the cluster of spots there.
0:32:07 > 0:32:11You can see one, two, three, four, five, six, seven spots there.
0:32:11 > 0:32:13And then it goes off to a circle...
0:32:13 > 0:32:18Over the past three years, Guy has recorded ten giants in the Maldives.
0:32:19 > 0:32:24By comparing the spot patterns of the Maldives and Mozambique giants,
0:32:24 > 0:32:27they're hoping to find a match.
0:32:27 > 0:32:29If they find a positive ID,
0:32:29 > 0:32:32it will prove the giants are travelling large distances.
0:32:32 > 0:32:36Is there any way we can zoom in on that a little bit?
0:32:36 > 0:32:41But with all the cross-referencing done by eye, it's a slow process.
0:32:41 > 0:32:45- I can say for sure that one's not in the population.- OK.
0:32:45 > 0:32:47- On to the next one. - On to the next one.
0:32:47 > 0:32:51Wow, that's very, sort of, dramatic markings, huh?
0:32:59 > 0:33:02Dawn on day two of Andrea's trip.
0:33:02 > 0:33:05And the photo comparison work is yet to find a match.
0:33:08 > 0:33:11But with more than 70 of Andrea's giants still to look at,
0:33:11 > 0:33:13there's a lot more work to be done.
0:33:25 > 0:33:27Out at sea,
0:33:27 > 0:33:29Andrea and Guy continue their hunt for giants
0:33:29 > 0:33:31amongst the huge numbers of reef mantas
0:33:31 > 0:33:34that have gathered, once again, at the Hanifaru lagoon.
0:33:37 > 0:33:41Today, the plankton is higher up in the water column.
0:33:43 > 0:33:47And now, great trains of mantas start forming just below the waves.
0:33:57 > 0:34:01- It's amazing how they move in huge groups right at the surface.- Exactly.
0:34:01 > 0:34:04They've learnt exactly where to be at what time.
0:34:04 > 0:34:06- A little more experience.- Exactly...
0:34:06 > 0:34:09Lining up behind each other in a staggered formation,
0:34:09 > 0:34:12the trains travel up and down the lagoon
0:34:12 > 0:34:15scooping up huge quantities of food.
0:34:21 > 0:34:24This feeding strategy is a deliberate and highly effective way
0:34:24 > 0:34:26of maximising their catch.
0:34:28 > 0:34:30As the animal plankton sense
0:34:30 > 0:34:33the pressure waves from the approaching mantas,
0:34:33 > 0:34:35they try to escape.
0:34:37 > 0:34:41But the following mantas, by moving in such a precise group,
0:34:41 > 0:34:45leave the plankton with few places to go.
0:34:47 > 0:34:51Sucked into the mantas' mouths, the feast is sieved from the water
0:34:51 > 0:34:54by finger-like structures called gill rakers.
0:34:57 > 0:35:02It's thought mantas can harvest more than 17 kilos of plankton a day.
0:35:08 > 0:35:10As the mantas begin to disperse,
0:35:10 > 0:35:13the world's largest fish arrives.
0:35:15 > 0:35:19Growing up to 12 metres long, the whale shark,
0:35:19 > 0:35:22like the mantas, feeds mainly on plankton.
0:35:35 > 0:35:37As Andrea's week comes to an end,
0:35:37 > 0:35:41there are still no sightings of any giant mantas.
0:35:41 > 0:35:44And the photo ID work also draws a blank.
0:35:46 > 0:35:49I had an amazing week here in the Maldives.
0:35:49 > 0:35:53I'm so glad that I found the time to come out here.
0:35:53 > 0:35:57This was our first step in trying to figure out if perhaps the giants
0:35:57 > 0:36:01were making migrations from the African coastline to the Maldives.
0:36:01 > 0:36:04But we didn't get any matches.
0:36:04 > 0:36:07Andrea will need a radical new approach
0:36:07 > 0:36:10if she's ever to find out where the giant mantas are going.
0:36:22 > 0:36:24Back in Mozambique,
0:36:24 > 0:36:29Andrea has taken delivery of two state-of-the-art tracking devices.
0:36:29 > 0:36:35I took a band off the spear gun to try and limit the amount of power.
0:36:35 > 0:36:41Her plan is to attach them to two giants to see where they go.
0:36:41 > 0:36:46Out on the water Andrea begins her search,
0:36:46 > 0:36:49but it's not just the mantas she has to look out for.
0:36:49 > 0:36:52When the water gets murky and you see a manta swimming by
0:36:52 > 0:36:54and it has blood trailing out of it,
0:36:54 > 0:36:56you always look over your shoulder and you think,
0:36:56 > 0:36:59"Jeez, what just did that?" And is it, you know, after me next?
0:37:07 > 0:37:12Tiger sharks, bull sharks and great whites all stalk these reefs.
0:37:19 > 0:37:23Down at 30 metres, there's no sign of any giants.
0:37:28 > 0:37:32Only the reef mantas are around.
0:37:32 > 0:37:3775% bear the scars of horrific shark bite wounds.
0:37:54 > 0:37:59Bites like these come from sharks over four metres in length.
0:38:05 > 0:38:10Quite why they're the victims of such frequent attacks is a mystery.
0:38:12 > 0:38:14There's nowhere else in the world
0:38:14 > 0:38:16where mantas get hunted on this scale.
0:38:21 > 0:38:23But Andrea's discovered they have a special way
0:38:23 > 0:38:26of surviving such terrible injuries.
0:38:29 > 0:38:32Tofo's reefs are a hotbed of activity.
0:38:38 > 0:38:42Creatures of all shapes and sizes come to the cleaning stations
0:38:42 > 0:38:46to be picked clean of parasites and dead skin.
0:38:59 > 0:39:02Injured mantas are frequent visitors here, too...
0:39:04 > 0:39:07..queuing up for the attention of this tiny fish.
0:39:09 > 0:39:11The butterflyfish.
0:39:17 > 0:39:21Andrea has found they specialise in bite wounds.
0:39:23 > 0:39:27Madonna, a female Andrea has known for more than five years,
0:39:27 > 0:39:30has a fresh injury on her flank.
0:39:31 > 0:39:33By nibbling her wound,
0:39:33 > 0:39:38the butterflyfish removes dead tissue, preventing infection,
0:39:38 > 0:39:43making the difference between life and death for Mozambique's mantas.
0:39:48 > 0:39:52Butterflyfish aren't the only specialist cleaners here.
0:39:54 > 0:39:57Schools of sergeant major damselfish
0:39:57 > 0:40:00concentrate on the area around Madonna's mouth.
0:40:03 > 0:40:07While cleaner wrasse swim right to the back of her throat
0:40:07 > 0:40:09to pick clean her gills.
0:40:20 > 0:40:22The giant mantas, when they're around,
0:40:22 > 0:40:26are frequent visitors to these cleaning stations, too.
0:40:28 > 0:40:32But with no sign of any today, Andrea will just have to keep
0:40:32 > 0:40:35returning here until her luck changes.
0:40:41 > 0:40:44Back on land there's better news.
0:40:47 > 0:40:49The listening station she set up in November
0:40:49 > 0:40:55is starting to reveal more about the reef mantas' secretive lives.
0:40:55 > 0:40:58Already from the first manta we tagged, Tri-Star,
0:40:58 > 0:40:59we've gotten some amazing data.
0:41:01 > 0:41:05Sometimes she spends up to eight hours on the reef.
0:41:05 > 0:41:06A lot of the mantas seem to be
0:41:06 > 0:41:09spending extraordinary amounts of time on the reef, cleaning,
0:41:09 > 0:41:12and that's something you don't see other places in the world.
0:41:12 > 0:41:15Most people are reporting mantas cleaning for small periods of time,
0:41:15 > 0:41:17maybe two hours max,
0:41:17 > 0:41:21but I think the mantas here are spending more time on the cleaning stations
0:41:21 > 0:41:24because they have these massive shark bite injuries.
0:41:31 > 0:41:35The data has thrown up some further surprises.
0:41:35 > 0:41:37None of the mantas that we tagged
0:41:37 > 0:41:41are spending any time at the cleaning stations during night-time hours,
0:41:41 > 0:41:45so where they go at night, whether they go offshore, or down the coast,
0:41:45 > 0:41:46remains a complete mystery.
0:41:48 > 0:41:53Andrea suspects they're moving out into open-water to feed,
0:41:53 > 0:41:55or to avoid the sharks,
0:41:55 > 0:41:58which are at their most active as the sun goes down.
0:42:02 > 0:42:07It's her first glimpse into what Tofo's mantas are doing at night.
0:42:15 > 0:42:20Four weeks later, and Andrea is facing a new problem.
0:42:24 > 0:42:27Not only are there still no giants around,
0:42:27 > 0:42:30but now her entire reef population has disappeared as well.
0:42:39 > 0:42:43In seven years, Andrea has never seen anything like it.
0:42:44 > 0:42:46Ah. That was a pretty rough day.
0:42:46 > 0:42:47We've been going out for ages
0:42:47 > 0:42:50and we can't seem to find a single ray in the ocean.
0:42:50 > 0:42:52I'm getting thoroughly frustrated.
0:42:52 > 0:42:58The conditions are fine, It's just, I don't know where the mantas went, so I'm pretty frustrated.
0:43:02 > 0:43:06It's hard, you know, when the animal you study doesn't show up
0:43:06 > 0:43:09for such a long period of time, you start to worry.
0:43:09 > 0:43:12And I've heard of other researchers in the world
0:43:12 > 0:43:14that have lost their manta populations
0:43:14 > 0:43:16and then that's it, they have to pack up and move somewhere else,
0:43:16 > 0:43:18so it does make you worry,
0:43:18 > 0:43:20but we have such a stable population here,
0:43:20 > 0:43:23I'm just hoping that that's not the case.
0:43:24 > 0:43:28Andrea has good reason to be concerned.
0:43:34 > 0:43:38Worldwide, entire manta populations are being wiped out.
0:43:41 > 0:43:46I think the first time I saw a dead manta, it was actually in Mozambique
0:43:46 > 0:43:49and fishermen pulled it up, it was actually an individual that I knew.
0:43:49 > 0:43:52And, I couldn't control myself.
0:43:52 > 0:43:55I was crying. It was really hard for me.
0:43:55 > 0:43:58Worst affected are mantas in South-East Asia...
0:44:01 > 0:44:03..their body parts used in Chinese medicine
0:44:03 > 0:44:06to treat illnesses from diabetes to the common cold.
0:44:10 > 0:44:15And increasingly there are reports of foreign fishing boats
0:44:15 > 0:44:18working Mozambique's 1,600-mile coastline.
0:44:26 > 0:44:28Four weeks later
0:44:28 > 0:44:30and still no mantas.
0:44:34 > 0:44:38An aerial survey is Andrea's last hope of finding them,
0:44:38 > 0:44:43or at least to uncover the reason for their disappearance.
0:44:43 > 0:44:46In the past, the mantas have vanished,
0:44:46 > 0:44:50but only for short periods when plankton levels have dropped.
0:44:51 > 0:44:55We've also had instances where a predator will come through the area,
0:44:55 > 0:44:57a great white shark or a pod of orcas,
0:44:57 > 0:45:00and everything will leave - whale sharks, manta rays,
0:45:00 > 0:45:03and sometimes they'll leave the area for up to three weeks.
0:45:03 > 0:45:04But even from the air,
0:45:04 > 0:45:08Andrea can see nothing to explain their baffling disappearance.
0:45:12 > 0:45:15So far we've seen turtles, humpback whales
0:45:15 > 0:45:17but none of the manta rays.
0:45:17 > 0:45:22They seem to have disappeared completely from about a 60km area.
0:45:25 > 0:45:30With her entire population of over 650 mantas missing...
0:45:30 > 0:45:32it's now a real crisis.
0:45:44 > 0:45:48'The thing that really gets to me is just the waiting.
0:45:49 > 0:45:51'I go out to sea, I check,
0:45:51 > 0:45:55'I am in contact with dive centres up and down the coastline.
0:45:55 > 0:45:59'I'm doing everything in my power to find my population.
0:45:59 > 0:46:02'I just don't know where else to look at this stage.'
0:46:09 > 0:46:14Two weeks later, and a full eight weeks since she last laid eyes on a manta,
0:46:14 > 0:46:17Andrea's luck looks like it's finally changing.
0:46:18 > 0:46:21I just got a call from one of the dive operators
0:46:21 > 0:46:23and there's mantas on the reef.
0:46:23 > 0:46:28I'm not sure which ones, but they could be giants so I've prepped the boats and we're ready to go out now.
0:46:34 > 0:46:36If there ARE giants around,
0:46:36 > 0:46:40it will finally be Andrea's chance to attach a tag.
0:46:51 > 0:46:55But in the gloomy depths, mantas are nowhere to be seen.
0:47:15 > 0:47:20Then, Andrea spots an unmistakable outline.
0:47:21 > 0:47:24With its distinct markings,
0:47:24 > 0:47:28the first manta to return to Tofo's reefs is a giant.
0:47:36 > 0:47:39Far more wary of humans than their smaller reef cousins,
0:47:39 > 0:47:43getting close to a giant is not going to be easy.
0:48:24 > 0:48:26Something has gone wrong.
0:48:30 > 0:48:32The tag has failed to attach.
0:48:50 > 0:48:51Not good.
0:48:56 > 0:48:58We're going to have that not happen again.
0:49:01 > 0:49:04There haven't been mantas for weeks, finally we have a great opportunity.
0:49:04 > 0:49:07They're back. There are individuals on the reef that are cooperative.
0:49:07 > 0:49:11- And now, it's just so disappointing. - Really disappointing.
0:49:11 > 0:49:14We're going to have to go back to the drawing board tonight,
0:49:14 > 0:49:18to figure out how to get this to work tomorrow, before these giants leave.
0:49:22 > 0:49:25Andrea decides she can't risk waiting until tomorrow.
0:49:25 > 0:49:29Right, copy that. We'll be swapping Richie over to this boat...
0:49:29 > 0:49:31If her giants leave the reef tonight,
0:49:31 > 0:49:34the chances are she won't see any more for weeks.
0:49:36 > 0:49:39With her project already months behind schedule,
0:49:39 > 0:49:40it's a delay she can't afford.
0:49:47 > 0:49:51Two hours later they've done all they can
0:49:51 > 0:49:54and the improvised tags are ready to go.
0:49:55 > 0:49:59Seems like it should be fine. But nothing's ever fine in science.
0:50:01 > 0:50:04But we'll try this one now.
0:50:17 > 0:50:2230 metres down, the giant is still circling the reef.
0:50:48 > 0:50:51It worked beautifully, I think.
0:50:51 > 0:50:52It went in perfect.
0:50:52 > 0:50:55I didn't see it again, but the tag looked so good when it moved off.
0:50:55 > 0:50:58I think it's in there for good.
0:50:58 > 0:51:02I hope it's on its way to, like, Bangladesh or something, far away.
0:51:03 > 0:51:07Oh, it went in and I was going to cry I was so happy.
0:51:07 > 0:51:09What a relief!
0:51:12 > 0:51:15It makes it all worth it, you know?
0:51:16 > 0:51:19So, first satellite-tagged manta in Africa.
0:51:19 > 0:51:22Got to give it a pretty special name now.
0:51:22 > 0:51:24- Simon.- No, not Simon.
0:51:28 > 0:51:32Two days later, Andrea tags her second giant.
0:51:35 > 0:51:40Both mantas are new to her database, and she names them Cook and Magellan
0:51:40 > 0:51:43after the famous oceanic explorers.
0:51:48 > 0:51:53The sat-tag will record the mantas' every move for the next 60 days.
0:51:54 > 0:51:57Then, if all goes to plan it will release and transmit
0:51:57 > 0:52:01the giants' secrets to a satellite deep in space...
0:52:09 > 0:52:13For now, all Andrea can do is wait.
0:52:21 > 0:52:25Meanwhile, reports come in of an alarming trend
0:52:25 > 0:52:26that could be a real threat
0:52:26 > 0:52:30to both the giants and Tofo's reef mantas.
0:52:32 > 0:52:35If you just go in to Google and type in "manta products"
0:52:35 > 0:52:38you come up with several sites that are selling fins,
0:52:38 > 0:52:42the gill rakers, skin... It's really alarming.
0:52:42 > 0:52:46What's so shocking is that with the click of a button
0:52:46 > 0:52:49I can actually add manta ray products to my purchase bin.
0:52:49 > 0:52:51I mean, it's that easy.
0:52:51 > 0:52:54These products are coming from India, they're coming from South-East Asia.
0:52:54 > 0:52:58But it's that quick. You can access them that quick online.
0:52:58 > 0:53:02The global online trade is a serious development.
0:53:04 > 0:53:07Andrea's seen for herself the devastation it can bring.
0:53:10 > 0:53:13I was just so sad that these animals were dead.
0:53:13 > 0:53:19I was angry that this is still allowed to happen in the world today,
0:53:19 > 0:53:22I'm angry that mantas aren't protected anywhere,
0:53:22 > 0:53:26and I'm frustrated in the fact that science is often a very slow road.
0:53:28 > 0:53:31So, yeah, I do get very emotional.
0:53:31 > 0:53:32I won't lie.
0:53:37 > 0:53:41Protecting her mantas and finding out where the giants are going
0:53:41 > 0:53:43couldn't be more critical.
0:53:50 > 0:53:52It's June and the satellite data
0:53:52 > 0:53:55that could be the key to the giants' survival
0:53:55 > 0:53:56is finally in.
0:53:58 > 0:54:02Cook's tag released early, after just 22 days.
0:54:04 > 0:54:07But the data it reveals is fascinating.
0:54:10 > 0:54:15It was always thought that mantas spent most of their time in shallow waters.
0:54:15 > 0:54:18But Cook behaved very differently,
0:54:18 > 0:54:24staying down between 50 and 150 metres for half of her journey.
0:54:24 > 0:54:27Why remains a mystery.
0:54:31 > 0:54:35Magellan's tag stayed on for the full 60 days.
0:54:35 > 0:54:38She made an incredible journey.
0:54:40 > 0:54:45Leaving Mozambique, she entered South African waters
0:54:45 > 0:54:49where 90 miles off Durban, the tag released.
0:54:51 > 0:54:55The last data shows Magellan heading into the cold waters
0:54:55 > 0:54:58of the southern Indian Ocean.
0:54:58 > 0:55:01It's a journey of over 700 miles...
0:55:01 > 0:55:04and the first evidence that Andrea's giants are,
0:55:04 > 0:55:08as she suspected, ocean wanderers.
0:55:11 > 0:55:15Where Magellan was heading will never be known.
0:55:15 > 0:55:19But the significance of the journey is enormous.
0:55:19 > 0:55:21It means protecting giants like Magellan
0:55:21 > 0:55:24will need international cooperation.
0:55:33 > 0:55:35As Andrea's year draws to a close,
0:55:35 > 0:55:39there's a breakthrough for Tofu's reef mantas, too.
0:55:39 > 0:55:42The latest listening station results are in.
0:55:42 > 0:55:47For the first time, Andrea now has tantalising clues
0:55:47 > 0:55:50about where her reef mantas give birth.
0:55:51 > 0:55:54Tri-Star was pregnant when tagged.
0:55:54 > 0:55:57And then, just as she was about to pup,
0:55:57 > 0:55:59she disappeared from the reef.
0:56:01 > 0:56:05What's really interesting about Tri-Star is that she only left
0:56:05 > 0:56:11the inshore area for about two weeks, so she probably didn't go very far.
0:56:11 > 0:56:13All of this data basically suggests to me
0:56:13 > 0:56:16that they are giving birth in the vicinity,
0:56:16 > 0:56:18just probably somewhere else,
0:56:18 > 0:56:23offshore, maybe in a bay or mangrove, but definitely within the vicinity.
0:56:29 > 0:56:30It's the first evidence
0:56:30 > 0:56:34that there may be a manta pupping ground close by,
0:56:34 > 0:56:38perhaps even in this estuary just 15 miles from Andrea's base.
0:56:41 > 0:56:44There are no other known pupping grounds in the world.
0:56:49 > 0:56:51With each new discovery,
0:56:51 > 0:56:55this remarkable stretch of coast becomes ever more precious.
0:57:00 > 0:57:03Andrea is now in talks with the Mozambique government
0:57:03 > 0:57:05to set up a marine reserve at Tofo.
0:57:09 > 0:57:12But the future for her newly-discovered giants
0:57:12 > 0:57:13is far more uncertain.
0:57:16 > 0:57:17It is terribly frightening
0:57:17 > 0:57:20that something as beautiful and important as a manta ray
0:57:20 > 0:57:24could ever be brought to the brink of extinction.
0:57:25 > 0:57:30To have found a new species in this modern day is remarkable.
0:57:33 > 0:57:39To lose them to unregulated fishing and to Chinese medicines
0:57:39 > 0:57:40would be a tragedy.
0:57:45 > 0:57:50I'm not quite sure what the future holds for them.
0:57:50 > 0:57:53I believe that they need to be protected,
0:57:53 > 0:57:55and certainly off the African coastline,
0:57:55 > 0:57:58I will not leave until I see that they are.