0:00:39 > 0:00:44The South Pacific is, on the face of it, still a healthy ocean.
0:00:47 > 0:00:50We depend on it.
0:00:50 > 0:00:52Over 60% of the world's fish catch
0:00:52 > 0:00:55comes from the Pacific.
0:00:55 > 0:00:57But like all oceans,
0:00:57 > 0:00:59it has little or no protection,
0:00:59 > 0:01:03so it may not stay healthy much longer.
0:01:06 > 0:01:10So what's being done to preserve its natural treasures?
0:01:14 > 0:01:18And what does the future hold for this fragile paradise?
0:01:38 > 0:01:43For the South Pacific, this is a critical time.
0:01:46 > 0:01:49It's changing in ways that, if left unchecked,
0:01:49 > 0:01:51could develop into a global crisis.
0:01:54 > 0:01:58Some of its residents have been through crisis before.
0:02:01 > 0:02:06Humpback whales were hunted so relentlessly during the last century
0:02:06 > 0:02:09that their numbers crashed by 90%.
0:02:16 > 0:02:19But recently, they've made a comeback,
0:02:19 > 0:02:23surging from 5,000 to 60,000 animals.
0:02:24 > 0:02:27Their blubber is no longer boiled down for oil.
0:02:30 > 0:02:35Today, these whales are greeted by boats loaded not with harpoons,
0:02:35 > 0:02:36but with tourists.
0:02:41 > 0:02:45The waters of Tonga are one of the few places in the world
0:02:45 > 0:02:49where it's legal to get in and meet the giants face to face.
0:03:11 > 0:03:15Some claim that to look into the eye of a whale
0:03:15 > 0:03:18is a life-changing experience.
0:03:44 > 0:03:48In the 1970s, a campaign to "Save the Whale"
0:03:48 > 0:03:50made the headlines around the world,
0:03:50 > 0:03:53and led to an unprecedented agreement
0:03:53 > 0:03:56to protect what remained of the world's whales.
0:03:59 > 0:04:04It proved that global pressure CAN save wildlife that's under threat.
0:04:12 > 0:04:17So what are the current threats to wildlife in the Pacific?
0:04:21 > 0:04:24It's no secret that the world is getting warmer.
0:04:27 > 0:04:31And the low-lying islands of the South Pacific are on the front line,
0:04:31 > 0:04:35as global warming causes sea levels to rise.
0:04:43 > 0:04:46On the Pacific island nation of Tuvalu,
0:04:46 > 0:04:50nowhere is higher than five metres above sea level.
0:04:58 > 0:05:02Tuvalu's nine atolls and islands are home to 12,000 people.
0:05:02 > 0:05:06Their contribution to global warming is tiny,
0:05:06 > 0:05:09but its impact on them is massive.
0:05:11 > 0:05:14Sea walls are the nation's only defence,
0:05:14 > 0:05:18but building higher walls is likely to prove futile.
0:05:18 > 0:05:20During big spring tides,
0:05:20 > 0:05:24seawater simply bubbles up through the ground.
0:05:38 > 0:05:44In 2006, the islanders experienced their highest tides ever.
0:05:46 > 0:05:50These islands could soon become uninhabitable.
0:05:50 > 0:05:54The seawater is poisoning the soil and groundwater.
0:05:58 > 0:06:02Eventually, the islands may have to be evacuated.
0:06:03 > 0:06:06This would be an unprecedented move -
0:06:06 > 0:06:09an entire nation relocated.
0:06:14 > 0:06:17So the ocean is threatening its islands,
0:06:17 > 0:06:19thanks to global warming.
0:06:21 > 0:06:26And yet, the Pacific is playing a massive part
0:06:26 > 0:06:28in slowing down climate change.
0:06:36 > 0:06:41The world's oceans have absorbed about half of all the carbon dioxide
0:06:41 > 0:06:44released so far into the atmosphere by industry,
0:06:44 > 0:06:47significantly reducing the greenhouse effect.
0:06:50 > 0:06:52But there's a catch -
0:06:52 > 0:06:56for the fish, all that extra carbon dioxide in the water
0:06:56 > 0:06:58can have some unwanted side effects.
0:07:01 > 0:07:06All life in the Pacific is dependent on the tiniest of creatures -
0:07:06 > 0:07:09the plankton that floats freely in the currents.
0:07:11 > 0:07:15One of the most plentiful is the sea butterfly,
0:07:15 > 0:07:19a tiny marine snail, which uses its enlarged foot
0:07:19 > 0:07:21to "fly" through the water.
0:07:28 > 0:07:33Sea butterflies are such important food for so many marine animals
0:07:33 > 0:07:36they have been dubbed the "potato chips of the ocean".
0:07:36 > 0:07:42But they could be under threat from all that extra carbon dioxide.
0:07:45 > 0:07:50Dissolved carbon dioxide is slowly turning the water more acidic,
0:07:50 > 0:07:54making it harder for sea butterflies to build their calcium shells.
0:07:57 > 0:08:00The loss of these swimming "potato chips"
0:08:00 > 0:08:03would have repercussions right up the food chain.
0:08:11 > 0:08:14And with a billion people around the world
0:08:14 > 0:08:16dependent on fish for their protein,
0:08:16 > 0:08:21fewer fish would clearly be bad news for people too.
0:08:23 > 0:08:25Of course, there's no need to worry
0:08:25 > 0:08:28IF the greenhouse gases are brought under control.
0:08:28 > 0:08:30Or is there?
0:08:32 > 0:08:34Although the burning of fossil fuels
0:08:34 > 0:08:37is often viewed as the biggest environmental threat,
0:08:37 > 0:08:41here in the Pacific, there are more pressing concerns.
0:08:42 > 0:08:44The fish may disappear
0:08:44 > 0:08:49long before the impact of climate change really takes hold.
0:08:55 > 0:09:00A leading group of ecologists recently predicted
0:09:00 > 0:09:04that in just 40 years, seafood will be off the menu.
0:09:07 > 0:09:11The problem has a lot to do with fishing.
0:09:23 > 0:09:29In Fiji, the villagers of Moturiki Island are fishing for dinner.
0:09:38 > 0:09:42Using a traditional fishing technique known as a fish drive,
0:09:42 > 0:09:45they work together to scare the fish off the reef
0:09:45 > 0:09:47and into an ever-smaller corral.
0:09:49 > 0:09:53Each year, in coastal waters around the Pacific's islands,
0:09:53 > 0:09:57subsistence fishermen catch around 80,000 tonnes of fish.
0:10:03 > 0:10:07In the past, there was always plenty more fish in the sea,
0:10:07 > 0:10:11but recently, catches have been declining.
0:10:12 > 0:10:14Why should this be?
0:10:14 > 0:10:17It could be that more efficient fishing gear,
0:10:17 > 0:10:22such as modern nylon nets coupled with growing island populations,
0:10:22 > 0:10:24has led to over-fishing.
0:10:27 > 0:10:30But catching too many fish
0:10:30 > 0:10:33may not be the main reason why there are now too few.
0:10:38 > 0:10:43Pacific coastal fish live and breed in the most fragile of habitats -
0:10:43 > 0:10:45coral reefs.
0:10:47 > 0:10:51But many reefs have been trampled on, smashed by boats,
0:10:51 > 0:10:54and even dynamited in the quest for fish.
0:10:54 > 0:10:58And damaged reefs support fewer fish.
0:10:58 > 0:11:02This could be why the fishermen are catching less.
0:11:05 > 0:11:09In Fiji, biologists are working with fishermen
0:11:09 > 0:11:13to bring the fish back by replanting the reefs.
0:11:13 > 0:11:16This is a coral nursery.
0:11:16 > 0:11:18But with wild corals already struggling,
0:11:18 > 0:11:21where have these coral seedlings come from?
0:11:24 > 0:11:27The coral gardeners monitor the reef,
0:11:27 > 0:11:29looking for corals that need a helping hand.
0:11:36 > 0:11:42Despite all this real estate, many corals end up clustered together.
0:11:42 > 0:11:45Crowded out, they will eventually die,
0:11:45 > 0:11:49so the gardeners uproot them, creating more space for some,
0:11:49 > 0:11:52and giving the uprooted ones a fresh start.
0:11:55 > 0:11:59Each coral head is broken down into a dozen or more fingers
0:11:59 > 0:12:03and each of these is tied onto a concrete disc.
0:12:07 > 0:12:11As every gardener knows, vigorous growth requires sunlight,
0:12:11 > 0:12:14plenty of nutrients and the right temperature.
0:12:14 > 0:12:17So the coral gardeners choose just the spot.
0:12:27 > 0:12:31Within six months, the corals are branching out.
0:13:13 > 0:13:17They're spaced out onto adjacent tables
0:13:17 > 0:13:21and, a year or two after planting, they're ready for harvesting.
0:13:27 > 0:13:30The coral heads are broken down once more.
0:13:30 > 0:13:33In the space of two years, a single finger of coral
0:13:33 > 0:13:36has multiplied into 50 or more.
0:13:40 > 0:13:43Some of these will be re-planted on fresh discs,
0:13:43 > 0:13:46while others will be returned to the reef.
0:13:49 > 0:13:52If replicated, coral gardening could help
0:13:52 > 0:13:55restore reefs throughout the Pacific.
0:13:55 > 0:13:57But its biggest success
0:13:57 > 0:14:00may be in sowing the seeds of conservation in the local fishermen.
0:14:08 > 0:14:13Within days, these cuttings will have stuck themselves to the reef,
0:14:13 > 0:14:15while reefs that were replanted a year ago
0:14:15 > 0:14:18are already starting to bloom.
0:14:19 > 0:14:22In a few more years, this area should be awash with fish.
0:14:27 > 0:14:32So there's hope for coastal fisheries on which local people depend.
0:14:32 > 0:14:36Out in the open ocean, it's another story.
0:14:36 > 0:14:38There is no protection here,
0:14:38 > 0:14:41and yet this is where most fish are now being caught.
0:14:44 > 0:14:48These may look like minnows, but they are tuna,
0:14:48 > 0:14:51each a healthy two kilos or more.
0:14:54 > 0:14:58Four different species are fished in the tropical Pacific.
0:14:58 > 0:15:00These are skipjack tuna,
0:15:00 > 0:15:03with some yellowfin tuna mixed in.
0:15:04 > 0:15:08But this boat is not setting nets.
0:15:11 > 0:15:15The ancient technique of fishing with rod and line
0:15:15 > 0:15:18is now practised on an industrial scale.
0:15:41 > 0:15:45The water jets break up the outline of the boat from below,
0:15:45 > 0:15:49and mimic the noise and commotion of baitfish when under attack.
0:15:51 > 0:15:54Meanwhile, live baitfish are strewn around the boat
0:15:54 > 0:15:56to keep the tuna interested.
0:16:02 > 0:16:04It may look like a lot of effort for a few fish,
0:16:04 > 0:16:11but this "pole and line" technique of fishing can be surprisingly effective.
0:16:16 > 0:16:22Fishing for export is now big business in the tropical Pacific,
0:16:22 > 0:16:25with tuna alone accounting for 30 times more fish
0:16:25 > 0:16:28than all the fish caught by subsistence fishermen.
0:16:32 > 0:16:36So is commercial fishing sustainable?
0:16:38 > 0:16:40Skipjack are the smallest,
0:16:40 > 0:16:43and by far the most abundant tuna species in the Pacific.
0:16:44 > 0:16:47They reach maturity in just a year
0:16:47 > 0:16:51and then spawn many times within a season.
0:16:51 > 0:16:54They seem to be the perfect catch,
0:16:54 > 0:16:56as their numbers just keep bouncing back.
0:17:06 > 0:17:10But not all marine life is so resilient.
0:17:10 > 0:17:12Thanks to modern fishing,
0:17:12 > 0:17:17some of the best-known animals of the Pacific are in deep trouble.
0:17:22 > 0:17:26Sharks have been top dog in the Pacific for millions of years.
0:17:28 > 0:17:30They control the numbers of other fish,
0:17:30 > 0:17:32and so play a vital role
0:17:32 > 0:17:35in keeping the underwater ecosystem healthy and diverse.
0:17:40 > 0:17:45In French Polynesia, grey reef sharks gather.
0:17:53 > 0:17:59While scalloped hammerheads patrol the Galapagos Islands,
0:17:59 > 0:18:04these are rare hot spots where sharks converge in large numbers.
0:18:04 > 0:18:06But divers claim this is just a fraction
0:18:06 > 0:18:09of the number of sharks they used to see.
0:18:15 > 0:18:17Many sharks are ocean migrants,
0:18:17 > 0:18:21travelling hundreds of miles in search of prey,
0:18:21 > 0:18:24like the oceanic whitetip.
0:18:28 > 0:18:30Amazingly, this may once have been
0:18:30 > 0:18:33the most abundant large animal on the planet.
0:18:35 > 0:18:40But it's fallen prey to fishermen's hooks and nets.
0:18:40 > 0:18:43Surveys suggest oceanic whitetips may have declined
0:18:43 > 0:18:46by a staggering 99%.
0:18:47 > 0:18:51It's like the disappearance of bison from America's great plains,
0:18:51 > 0:18:55yet it's only happened in the past 50 years,
0:18:55 > 0:18:58and almost no-one has noticed.
0:19:00 > 0:19:04Incredibly, the world's oceans may have lost more than 90%
0:19:04 > 0:19:08of their large predatory fish since industrialised fishing began.
0:19:15 > 0:19:18Tiger sharks still turn up in Hawaiian waters,
0:19:18 > 0:19:22drawn here by another great ocean wanderer.
0:19:39 > 0:19:43These black-footed albatross are certainly an endangered species,
0:19:43 > 0:19:46but not because of the sharks.
0:19:47 > 0:19:50Thousands of adult black-footed albatross
0:19:50 > 0:19:54are caught each year on fishing lines.
0:19:55 > 0:19:59In fact, 19 of the world's 22 species of albatross
0:19:59 > 0:20:02are endangered or vulnerable to extinction,
0:20:02 > 0:20:03largely thanks to fishing.
0:20:10 > 0:20:13The Antipodean, or wandering albatross
0:20:13 > 0:20:15is found in the waters around New Zealand,
0:20:15 > 0:20:19home to the most diverse sea bird community in the world.
0:20:25 > 0:20:28These are rich fishing grounds for fishermen too.
0:20:37 > 0:20:41The birds know that where there are fishermen,
0:20:41 > 0:20:43a free lunch is sure to follow.
0:20:43 > 0:20:46So how does this get them into trouble?
0:20:48 > 0:20:52With a wingspan over three metres, an albatross is built to soar
0:20:52 > 0:20:55thousands of miles across the ocean in its quest for food.
0:20:59 > 0:21:03As it might go for days with nothing,
0:21:03 > 0:21:04it can't afford to be choosy.
0:21:08 > 0:21:11Anything near the surface is snapped up.
0:21:26 > 0:21:31Unfortunately, not everything a fisherman casts overboard
0:21:31 > 0:21:32is a healthy meal.
0:21:34 > 0:21:40Far out at sea, a long-line fishing vessel is setting its line.
0:21:40 > 0:21:44It's long-line vessels in particular that have been held responsible
0:21:44 > 0:21:46for the decline of the albatross.
0:21:51 > 0:21:55The fishermen pay out a line 30 miles long
0:21:55 > 0:21:57across the surface of the ocean,
0:21:57 > 0:22:00and every few metres, they attach a secondary line
0:22:00 > 0:22:03with a hook, baited with a fish or squid.
0:22:05 > 0:22:09Every night, this vessel casts over 1,000 hooks,
0:22:09 > 0:22:12and it is just one of many long-liners plying the Pacific,
0:22:12 > 0:22:16some with lines 100 miles long.
0:22:19 > 0:22:23But this fisherman is well aware of the threat to the sea birds,
0:22:23 > 0:22:26and to prevent them from swallowing his hooks,
0:22:26 > 0:22:29he has adopted bird-friendly fishing methods.
0:22:31 > 0:22:35It's why he sets his lines at night, when the albatross are sleeping.
0:22:36 > 0:22:38And he deploys "tori lines".
0:22:38 > 0:22:42These simple streamers are remarkably effective
0:22:42 > 0:22:45at scaring birds away from the hooks.
0:22:50 > 0:22:53He also thaws out his bait before hooking it,
0:22:53 > 0:22:55so it sinks out of sight quickly.
0:22:59 > 0:23:03His bird catch is now virtually zero.
0:23:06 > 0:23:12This leaves more hooks free for his target species - bigeye tuna.
0:23:15 > 0:23:19These are powerful fish, and can weigh well over 100 kilos.
0:23:22 > 0:23:26It may look brutal, but the most humane way to kill one quickly
0:23:26 > 0:23:28is to shoot it.
0:23:49 > 0:23:54The future of the albatross still hangs in the balance.
0:23:54 > 0:23:57The birds around New Zealand are benefiting from a law that states
0:23:57 > 0:24:02all long-line fishing vessels must use bird-friendly methods.
0:24:02 > 0:24:05But albatross are great travellers,
0:24:05 > 0:24:10so they're still at risk throughout the rest of the South Pacific.
0:24:10 > 0:24:14Only if all fishing vessels adopt the same bird-friendly techniques
0:24:14 > 0:24:16will the story of the albatross -
0:24:16 > 0:24:19like that of the whale - have a happy ending.
0:24:23 > 0:24:27Saving sharks is not so straightforward.
0:24:27 > 0:24:30They're not just caught accidentally -
0:24:30 > 0:24:32their fins are worth a fortune,
0:24:32 > 0:24:36thanks to an Oriental taste for shark-fin soup.
0:24:40 > 0:24:45Over 70 million sharks are killed every year,
0:24:45 > 0:24:48many in the South Pacific, where shark-finning is neither outlawed
0:24:48 > 0:24:50nor properly regulated.
0:24:53 > 0:24:55This is a bigeye thresher,
0:24:55 > 0:24:59a shark that's almost never been seen in the wild.
0:25:09 > 0:25:14Shark-finning is a wasteful and often cruel practice,
0:25:14 > 0:25:18and one that may ultimately disrupt the balance of life in the ocean,
0:25:18 > 0:25:21proving catastrophic for other marine life too.
0:25:25 > 0:25:28So how can sharks be saved?
0:25:35 > 0:25:40In Bega Lagoon, in Fiji, the local people are proving
0:25:40 > 0:25:43that sharks can be more valuable alive than dead.
0:25:47 > 0:25:53Tourists will pay good money for an encounter with real, live sharks.
0:25:53 > 0:25:56This is a community-owned reef
0:25:56 > 0:25:59and some of the money goes to the local villagers -
0:25:59 > 0:26:03a big incentive not to kill the main attraction.
0:26:05 > 0:26:09Fijians have long had an affinity with sharks.
0:26:09 > 0:26:11Their ancestors worshipped a shark god,
0:26:11 > 0:26:15who they believed kept them safe from harm.
0:26:15 > 0:26:18They would feed sharks, not hunt them,
0:26:18 > 0:26:21and these divers continue the tradition.
0:26:21 > 0:26:25First to the feast are tawny nurse sharks.
0:26:26 > 0:26:29But these sharks are scavengers.
0:26:31 > 0:26:35It's the big predators the tourists want to see.
0:26:42 > 0:26:45Bull sharks.
0:26:45 > 0:26:47Growing up to three-and-a-half metres long,
0:26:47 > 0:26:50these sharks are one of the ocean's top predators,
0:26:50 > 0:26:53with an aggressive reputation.
0:27:09 > 0:27:11The chief shark feeder
0:27:11 > 0:27:14is from a village where the shark god is still worshiped.
0:27:14 > 0:27:17So he has no fear.
0:27:24 > 0:27:28A bowl of shark-fin soup can sell for over 100 dollars,
0:27:28 > 0:27:32but here, each tourist pays that to see these sharks alive
0:27:32 > 0:27:36and dives take place several times each week.
0:27:40 > 0:27:42To protect the sharks,
0:27:42 > 0:27:45this reef has now been declared a marine reserve...
0:27:47 > 0:27:51..with the added bonus that other fish are protected too.
0:28:02 > 0:28:06Before the reserve was established, this reef had been fished-out.
0:28:08 > 0:28:13Even a single giant trevally of this size was a rarity.
0:28:16 > 0:28:20Today, the divers are in for a special treat.
0:28:44 > 0:28:47A five-metre tiger shark.
0:29:09 > 0:29:12The dive leaders have named her Scarface.
0:29:12 > 0:29:15She turns up once a month or so.
0:29:33 > 0:29:36She's inquisitive, but not aggressive.
0:29:46 > 0:29:48The show's over.
0:29:48 > 0:29:52The divers have had a great day, and local people benefit too.
0:29:52 > 0:29:57With so many fish, some spill over into the waters beyond the reserve,
0:29:57 > 0:29:59where fishermen now catch many more
0:29:59 > 0:30:02than they did before the reserve was set up.
0:30:05 > 0:30:08Marine reserves clearly work.
0:30:08 > 0:30:11So why aren't there more of them?
0:30:11 > 0:30:17In truth, marine protection is decades behind wildlife protection on land.
0:30:17 > 0:30:20Take the islands of New Zealand.
0:30:20 > 0:30:26Beyond the farmed landscape are wild places where nature can flourish.
0:30:29 > 0:30:32More than a quarter of the country is set aside
0:30:32 > 0:30:35in national parks and other reserves.
0:30:42 > 0:30:47In contrast, less than 1% of the Pacific Ocean is protected.
0:30:50 > 0:30:54Instead, it is divided up into fishing zones.
0:30:56 > 0:31:02Each island nation owns the fishing rights up to 200 miles offshore.
0:31:03 > 0:31:07Beyond these territorial waters are the so-called "high seas".
0:31:08 > 0:31:10Bounded by national waters,
0:31:10 > 0:31:13the high-seas pockets of the western Pacific
0:31:13 > 0:31:16cover half a million square miles.
0:31:18 > 0:31:21The surrounding island nations would like these pockets
0:31:21 > 0:31:23to be declared marine reserves -
0:31:23 > 0:31:26safe havens where migratory fish can breed.
0:31:27 > 0:31:31The idea is being promoted by Greenpeace.
0:31:31 > 0:31:36Greenpeace made their name campaigning to save the whales.
0:31:36 > 0:31:38They're now responding to concerns
0:31:38 > 0:31:40about the future of the Pacific's fish.
0:31:42 > 0:31:45The high-seas pockets they're now patrolling
0:31:45 > 0:31:47were once a fishing free-for-all.
0:31:47 > 0:31:50Although now regulated by international treaty,
0:31:50 > 0:31:52they are rarely policed,
0:31:52 > 0:31:56so Greenpeace have assigned a monitoring role to themselves.
0:31:59 > 0:32:02This is the Esperanza -
0:32:02 > 0:32:04Greenpeace's largest vessel.
0:32:04 > 0:32:07The crew are searching for any sign of fishing activity
0:32:07 > 0:32:10but it's a huge area.
0:32:14 > 0:32:18After two weeks at sea, a blip on the radar indicates
0:32:18 > 0:32:19a fishing vessel is near.
0:32:21 > 0:32:22Greenpeace want to discover
0:32:22 > 0:32:26where the vessel is from and what it's been catching.
0:32:28 > 0:32:30They launch their inflatable boats.
0:32:31 > 0:32:35Although Greenpeace film their own activities,
0:32:35 > 0:32:40we put our cameraman on board to ensure an unbiased record of events.
0:32:48 > 0:32:53As these are international waters, any nation can fish here legally,
0:32:53 > 0:32:55and many do, including the US,
0:32:55 > 0:32:59the European Union, Japan and other East Asian countries.
0:33:04 > 0:33:08This is a large Taiwanese long-liner.
0:33:10 > 0:33:14Taiwan has a large fishing fleet, with many vessels fishing
0:33:14 > 0:33:17almost exclusively in international waters.
0:33:19 > 0:33:22The encounter turns out to be entirely amicable.
0:33:25 > 0:33:29Visitors are rare for fishermen on the high seas,
0:33:29 > 0:33:33and these men are not aware they have anything to hide.
0:33:33 > 0:33:36Greenpeace ask if they can inspect the vessel's catch
0:33:36 > 0:33:39and the fishermen oblige.
0:33:39 > 0:33:42In a freezer, there are several dozen frozen sharks
0:33:42 > 0:33:46but the valuable parts are being stored elsewhere.
0:33:46 > 0:33:48The shark fin, what do you...?
0:33:48 > 0:33:52- Do you sell them in Taiwan too? - No, no.
0:33:52 > 0:33:56In another freezer are a dozen sacks of shark fins.
0:34:00 > 0:34:02The fins from hundreds of sharks.
0:34:04 > 0:34:08By documenting these catches, Greenpeace hope to highlight
0:34:08 > 0:34:13why it's necessary to declare these high-sea pockets marine reserves,
0:34:13 > 0:34:18and to back the growing movement from Pacific Islanders for protection.
0:34:18 > 0:34:21This would help to protect all ocean life,
0:34:21 > 0:34:24especially the valuable tuna.
0:34:27 > 0:34:29Tuna are predators.
0:34:29 > 0:34:32They herd smaller fish to the surface,
0:34:32 > 0:34:35where they can be picked off one by one.
0:34:45 > 0:34:49They are high-speed fish - the cheetahs of the ocean.
0:34:51 > 0:34:57They're also the wildebeest - they herd together in their thousands
0:34:57 > 0:35:00and undertake epic migrations across the Pacific in search of their prey.
0:35:03 > 0:35:06If these animals lived on land,
0:35:06 > 0:35:10they'd be famous for providing the greatest wildlife spectacle on Earth.
0:35:12 > 0:35:18Instead, they're better known as a filling for a sandwich.
0:35:21 > 0:35:27In an ocean with no marine reserves, migratory fish have nowhere to hide.
0:35:32 > 0:35:37Up to 2 kilometres long and 200 metres deep,
0:35:37 > 0:35:41"purse seine" nets are designed to encircle schools of tuna.
0:35:56 > 0:36:00A fisherman checks his nets, breathing air pumped down a tube
0:36:00 > 0:36:02from the vessel above.
0:36:07 > 0:36:10It's not only tuna that get caught in these nets.
0:36:25 > 0:36:29A lone turtle was in the wrong place at the wrong time.
0:36:33 > 0:36:36She can only hold her breath for a few minutes
0:36:36 > 0:36:40and the path to the surface isn't clear.
0:36:46 > 0:36:48She begins to panic.
0:37:09 > 0:37:14These fishermen are superstitious about turtles.
0:37:14 > 0:37:16Bringing one on board
0:37:16 > 0:37:18is bad luck.
0:37:21 > 0:37:24It's her lucky day.
0:37:26 > 0:37:29More and more fishing vessels are being drawn
0:37:29 > 0:37:33to the South Pacific each year, as this is one of the last oceans
0:37:33 > 0:37:36where healthy numbers of fish still remain.
0:37:36 > 0:37:37But for how much longer?
0:37:39 > 0:37:43Fishing is now a high-tech operation, with radar picking up
0:37:43 > 0:37:48distant flocks of birds that indicate fish feeding below.
0:37:51 > 0:37:56The net is paid out in a wide circle around the fish.
0:37:56 > 0:38:01It's a race against time, as the fish could disappear at any moment.
0:38:16 > 0:38:21As the circle closes, pellets of dye are dropped into the water.
0:38:29 > 0:38:32The dye, and the speedboats overhead,
0:38:32 > 0:38:35discourage the tuna from making a dash through the closing gap
0:38:35 > 0:38:37in the wall of net.
0:38:51 > 0:38:53As the net closes,
0:38:53 > 0:38:57a draw-cord running along the bottom of the net is pulled tight.
0:39:06 > 0:39:11The net becomes a bag, or "purse", and the fish are trapped.
0:39:25 > 0:39:30There are 150 tonnes of fish in this one haul.
0:39:30 > 0:39:35It used to take a fishing vessel one whole year to catch this many fish.
0:39:40 > 0:39:46These are mostly yellowfin tuna, plus some skipjack.
0:39:48 > 0:39:51As they're slower breeders than skipjack,
0:39:51 > 0:39:54many yellowfin are caught before they're old enough to breed.
0:39:54 > 0:39:57This makes them more vulnerable to over-fishing.
0:40:00 > 0:40:05Tuna fishing has grown into an eight-billion dollar industry.
0:40:07 > 0:40:12And over four million tonnes of tuna are caught worldwide each year,
0:40:12 > 0:40:15a four-fold increase in as many decades.
0:40:18 > 0:40:22Almost two-thirds of the catch now comes from the Pacific.
0:40:30 > 0:40:35In the Atlantic, yellowfin catches have been shrinking since 1990.
0:40:35 > 0:40:38Now a similar decline has begun in the Pacific.
0:40:49 > 0:40:52Tuna need to swim constantly
0:40:52 > 0:40:57to keep water flowing over their gills, otherwise they can't breathe.
0:41:13 > 0:41:17The fishermen want to get them out of the water as quickly as possible.
0:41:17 > 0:41:21When starved of oxygen, a build-up of lactic acid in their muscles
0:41:21 > 0:41:24causes the quality of their meat to deteriorate.
0:41:46 > 0:41:50The fish are scooped up from the water, a tonne or two at a time.
0:41:54 > 0:41:56Every last fish from this school
0:41:56 > 0:42:01of 7,000 yellowfin and skipjack tuna is plucked from the water.
0:42:10 > 0:42:13With fishing techniques now so efficient,
0:42:13 > 0:42:16and with ever more vessels plying the Pacific,
0:42:16 > 0:42:18there is real concern among biologists
0:42:18 > 0:42:22that even the resilient skipjack may begin to decline.
0:42:37 > 0:42:40This vessel is not one of the newcomers.
0:42:40 > 0:42:45It's a Papua-New-Guinea-flagged ship, fishing in their territorial waters.
0:42:48 > 0:42:50So it's subject to catch limits
0:42:50 > 0:42:53and regulations that are amongst the strictest in the Pacific,
0:42:53 > 0:42:58designed to ensure that tuna fishing remains sustainable.
0:42:58 > 0:43:00But New Guinea's fishermen are concerned
0:43:00 > 0:43:02about the increasing numbers
0:43:02 > 0:43:05of foreign vessels now fishing for Pacific tuna.
0:43:06 > 0:43:09They were the first nation to propose
0:43:09 > 0:43:12that the high-seas pockets beyond their national waters
0:43:12 > 0:43:16be declared marine reserves, as now advocated by Greenpeace.
0:43:20 > 0:43:23After our cameraman left the Esperanza,
0:43:23 > 0:43:25Greenpeace continued their journey,
0:43:25 > 0:43:28and captured these images of the world's biggest purse seiner,
0:43:28 > 0:43:33with a capacity almost four times larger than the New Guinea vessel.
0:43:33 > 0:43:38It's a Spanish ship fishing for Pacific tuna
0:43:38 > 0:43:40to stock European supermarkets.
0:43:42 > 0:43:44The presence of such large vessels,
0:43:44 > 0:43:48from countries that have already over-fished their own tuna stocks,
0:43:48 > 0:43:51has riled the operators of local fishing fleets,
0:43:51 > 0:43:55perhaps with some justification.
0:43:56 > 0:44:01Some biologists have recently warned that tuna populations in the Pacific
0:44:01 > 0:44:06will be crashing within five years unless urgent action is taken.
0:44:11 > 0:44:15Perhaps it's time to think again about the ways we fish.
0:44:26 > 0:44:30These pole and line fishermen are Solomon Islanders,
0:44:30 > 0:44:33and this fishing is a local industry.
0:44:58 > 0:45:03They target specific species, and mature individuals.
0:45:03 > 0:45:09There's almost no by-catch - no sea birds, no sharks.
0:45:21 > 0:45:25And they can be selective, flicking juvenile fish off their hooks
0:45:25 > 0:45:28so they can grow and breed.
0:45:30 > 0:45:34Because it's impossible to hook every last fish in a school,
0:45:34 > 0:45:37some are always left to fight another day.
0:45:41 > 0:45:45And since the fish don't suffer for hours in nets,
0:45:45 > 0:45:48this meat is of a high quality.
0:46:24 > 0:46:29These fishermen may not catch as many fish as a purse seiner,
0:46:29 > 0:46:33but then, that's the point.
0:46:59 > 0:47:02Whether any fishing is sustainable
0:47:02 > 0:47:06depends on how many fish are caught, how many are left to breed
0:47:06 > 0:47:10and how many other species are caught by accident.
0:47:12 > 0:47:15But these fishermen may have got it about right.
0:47:17 > 0:47:21The Marine Stewardship Council assesses the environmental impacts
0:47:21 > 0:47:24of the world's fisheries, and they believe
0:47:24 > 0:47:26that pole and line fisheries have the potential
0:47:26 > 0:47:28to be approved as officially sustainable.
0:47:31 > 0:47:34So now it's down to us, the fish-eaters.
0:47:36 > 0:47:38It may cost a few pennies more
0:47:38 > 0:47:41to buy a tin of tuna labelled "sustainably caught",
0:47:41 > 0:47:46but it could ensure future generations can also enjoy a tuna sandwich,
0:47:46 > 0:47:48tuna steak or sashimi.
0:47:52 > 0:47:55And protecting the fish will ensure a healthy ocean
0:47:55 > 0:47:58for all the marine life of the Pacific.
0:47:59 > 0:48:03It will require international commitment and co-operation,
0:48:03 > 0:48:07but the whales are a reminder that it can be done.
0:48:15 > 0:48:20For the whales, for the fish, and for ourselves,
0:48:20 > 0:48:23the way we harvest the Pacific is key
0:48:23 > 0:48:27to protecting this fragile ocean paradise.
0:48:58 > 0:49:01To film the purse seine fishing sequence,
0:49:01 > 0:49:05the South Pacific team decided they would need to put a cameraman
0:49:05 > 0:49:06inside the fishing net.
0:49:08 > 0:49:12Few divers have ever attempted this before
0:49:12 > 0:49:14and it proved to be a real challenge.
0:49:20 > 0:49:23To be in the right spot at the right time,
0:49:23 > 0:49:26the film crew have to take up residence on a purse seine vessel.
0:49:26 > 0:49:33This 60-metre Papua New Guinea vessel can hold 800 tonnes of fish.
0:49:33 > 0:49:38For the 30-strong, all-male crew this boat is home.
0:49:41 > 0:49:44They spend 330 days of the year at sea,
0:49:44 > 0:49:47and can go two years without seeing their families.
0:49:49 > 0:49:53Their lives are a never-ending quest for fish.
0:49:54 > 0:49:56They're in port for three days,
0:49:56 > 0:49:58which gives the film crew a chance
0:49:58 > 0:50:01to jump on board.
0:50:01 > 0:50:02Here we are.
0:50:09 > 0:50:10It's a vast ocean,
0:50:10 > 0:50:13and even the fishermen don't know where the fish are,
0:50:13 > 0:50:17so they set a course for the location of their last big catch.
0:50:17 > 0:50:21The film crew have arranged for a dive boat to meet them there.
0:50:21 > 0:50:24Without the support of a professional dive boat,
0:50:24 > 0:50:27it would be dangerous to get in the water and film.
0:50:28 > 0:50:32Just hours after leaving, reports come in
0:50:32 > 0:50:33of big tuna catches up north,
0:50:33 > 0:50:36and the captain sets a new course.
0:50:36 > 0:50:40This is not good news for the team.
0:50:41 > 0:50:44Our dive boat is based out of here...
0:50:44 > 0:50:47and we're gonna be up here.
0:50:47 > 0:50:50For the dive boat, that would be about 45 hours.
0:50:50 > 0:50:54This new location is well out of range of the dive boat.
0:50:54 > 0:50:58With the success of the shoot hinging on the diving,
0:50:58 > 0:51:00this is a worrying turn of events.
0:51:00 > 0:51:03The fishing boat motors on all night, taking the team
0:51:03 > 0:51:06further and further from their planned rendezvous.
0:51:09 > 0:51:12Our position now is three degrees...
0:51:12 > 0:51:16Eventually, the crew make contact with a passing fishing boat,
0:51:16 > 0:51:20and it's heading back in the direction of their dive boat.
0:51:20 > 0:51:21There is another boat out here,
0:51:21 > 0:51:25which is going on a much better course, so we're gonna transfer.
0:51:28 > 0:51:32It's a lucky escape for the team.
0:51:32 > 0:51:35The new vessel spends all day and all night
0:51:35 > 0:51:38motoring towards the new fishing grounds.
0:51:38 > 0:51:428.28 in the morning, and we've already discovered fish.
0:51:42 > 0:51:44Right out there, about 150 metres,
0:51:44 > 0:51:47the sea is frothing and boiling
0:51:47 > 0:51:49and that's obviously where the tuna are,
0:51:49 > 0:51:53so the ship is doing a circle round it and that's where they'll set the nets.
0:51:53 > 0:51:55It's all on, it's all on.
0:52:00 > 0:52:03Although it's a relief to begin filming,
0:52:03 > 0:52:05the real challenge is still to come.
0:52:05 > 0:52:08They need to get inside the net,
0:52:08 > 0:52:12and right now, that's not a very inviting prospect.
0:52:13 > 0:52:18But first, they need their dive boat to find them in this vast expanse.
0:52:18 > 0:52:23I can see our dive boat on the horizon. She's a little spec in the distance.
0:52:25 > 0:52:28Here we go again, ship transfer.
0:52:28 > 0:52:31There you go, that's our new home.
0:52:32 > 0:52:33See you tomorrow.
0:52:38 > 0:52:42At five in the morning, the fishermen are already setting the nets.
0:52:42 > 0:52:46It's time to take the plunge.
0:52:46 > 0:52:49It may seem a little strange
0:52:49 > 0:52:51why we're putting fishing net on our scuba gear,
0:52:51 > 0:52:56but it has a very useful purpose. These jagged edges of the gear
0:52:56 > 0:52:59are completely covered with this fishing net
0:52:59 > 0:53:02to prevent us from getting snagged and caught like fish.
0:53:02 > 0:53:07I don't normally wear a knife this big, but in this kind of situation,
0:53:07 > 0:53:12with all the nets around and the possibility of entanglement,
0:53:12 > 0:53:13it's a really good idea.
0:53:13 > 0:53:18This is a shark shield, and with a tuna-fishing boat,
0:53:18 > 0:53:21thousands of bloody tuna in the water,
0:53:21 > 0:53:24and a sea full of sharks, it could come in very handy.
0:53:24 > 0:53:27They enter the net.
0:53:32 > 0:53:36Despite having done all they can to prepare,
0:53:36 > 0:53:39this is a jump into the unknown.
0:53:42 > 0:53:45The scale of the net is breathtaking.
0:53:49 > 0:53:53They're relieved to find that there are no sharks this time.
0:53:53 > 0:53:56But there are also no fish.
0:54:00 > 0:54:02Frustratingly, days pass
0:54:02 > 0:54:04and the fishermen fail to find any more fish.
0:54:04 > 0:54:06We're going down to the wire here.
0:54:06 > 0:54:10We've got two days left and we still haven't seen any fish,
0:54:10 > 0:54:13so getting a little nervous.
0:54:13 > 0:54:19Yeah, it'd be tragic to be out here and not have the opportunity to film this.
0:54:20 > 0:54:23Eventually, they locate a school.
0:54:23 > 0:54:27So the question is, are there any fish in that net?
0:54:27 > 0:54:32This is the team's last chance to get the sequence.
0:54:41 > 0:54:45To their great relief, all their effort has finally paid off.
0:54:54 > 0:54:59They share the net with 150 tonnes of tuna -
0:54:59 > 0:55:02one of the biggest catches of the year.
0:55:04 > 0:55:07It's an intense experience.
0:55:10 > 0:55:13Once again, there are no sharks.
0:55:14 > 0:55:19But as the net tightens, the space inside gets ever smaller.
0:55:23 > 0:55:25The fish begin to panic.
0:55:32 > 0:55:34Eventually, the crew have to bail out.
0:55:38 > 0:55:41They continue to film from outside the net.
0:55:52 > 0:55:55The filming has been a success,
0:55:55 > 0:55:59but seeing death on this scale has quite an impact on the team.
0:56:10 > 0:56:12Speechless, really.
0:56:12 > 0:56:15It was...unbelievable
0:56:22 > 0:56:26Really. It's hard to find words to describe that.
0:56:30 > 0:56:35At first you got in, it was just empty, there's just that serene silence, that...
0:56:35 > 0:56:41Turn around, and all of a sudden, this whole space is filled with fish,
0:56:41 > 0:56:45just frenetic, fast-moving fish just going crazy.
0:56:45 > 0:56:48From then on in, it was just absolutely intense.
0:56:48 > 0:56:50You don't know which is up or down or side.
0:56:50 > 0:56:52Your whole frame of reference goes off.
0:56:52 > 0:56:56And finally, the net was the one static point, wasn't it?
0:56:56 > 0:56:58At the start of the dive, you feel like the net
0:56:58 > 0:57:01is something to keep away from, but by the end of the dive
0:57:01 > 0:57:04the net is the only thing you can use as a frame of reference
0:57:04 > 0:57:08and everything else is just moving, and it's very disorientating.
0:57:10 > 0:57:12And there were other surprises.
0:57:14 > 0:57:18The slick of blood that comes from this is just, like, pouring out of the net
0:57:18 > 0:57:22in this massive slick, and you would have thought in this ocean
0:57:22 > 0:57:25it would have attracted hundreds of sharks,
0:57:25 > 0:57:27but I didn't see a single one, not one shark.
0:57:28 > 0:57:33It's a worrying sign that all is not well in the South Pacific.
0:57:33 > 0:57:36So what of the fish?
0:57:36 > 0:57:41What we saw today was a highly-unique experience
0:57:41 > 0:57:46and I think it does make you wonder what our impact on the oceans are
0:57:46 > 0:57:48when you see it first-hand like that.
0:57:50 > 0:57:52The team were lucky.
0:57:52 > 0:57:57With so many vessels now fishing throughout the Pacific,
0:57:57 > 0:58:01it may not be possible to film scenes like these for very much longer.
0:58:25 > 0:58:27Subtitles by Red Bee Media Ltd
0:58:27 > 0:58:29E-mail subtitling@bbc.co.uk