0:00:04 > 0:00:10The power of the sun drives the seasons, transforming our planet.
0:00:11 > 0:00:16Vast movements of ocean and air currents bring dramatic change
0:00:16 > 0:00:18throughout the year.
0:00:22 > 0:00:27And in a few special places, these seasonal changes create
0:00:27 > 0:00:30some of the greatest wildlife spectacles on Earth.
0:00:33 > 0:00:37The most dramatic event in the world's oceans happens
0:00:37 > 0:00:41off the eastern shores of South Africa.
0:00:45 > 0:00:49These cool waters create the perfect conditions
0:00:49 > 0:00:52for a spectacle of epic proportions.
0:00:56 > 0:01:00And everything revolves around the humble sardine.
0:01:04 > 0:01:08Each year, millions of them are swept up Africa's coast
0:01:08 > 0:01:10on a desperate winter journey.
0:01:15 > 0:01:18Following them comes what will become
0:01:18 > 0:01:21the biggest army of predators anywhere on the planet.
0:01:28 > 0:01:32The climax to this chase depends on many crucial elements
0:01:32 > 0:01:35coming together for one brief moment in time.
0:01:41 > 0:01:45This can well claim to be the greatest SHOAL on Earth.
0:02:09 > 0:02:13In the deep water off the southern tip of Africa
0:02:13 > 0:02:16lie the rich fishing grounds of the Agulhas Bank.
0:02:20 > 0:02:25It's home to billions of sardines. They live in immense shoals
0:02:25 > 0:02:28as defence against their many predators.
0:02:34 > 0:02:37Moving together as one in a shoal
0:02:37 > 0:02:42gives an individual sardine its best chance of survival.
0:02:45 > 0:02:47Sardines are so numerous,
0:02:47 > 0:02:51they're on the menu of most fish-eating predators here.
0:02:59 > 0:03:04It's summer, and the sardines are lost in the vastness of the ocean.
0:03:04 > 0:03:07The shoals are so dispersed, they're hard to find.
0:03:24 > 0:03:29Common dolphins are specialist sardine hunters.
0:03:39 > 0:03:41Dolphins aren't the only ones on their trail.
0:03:41 > 0:03:45Gannets also rely on a diet of sardines.
0:03:47 > 0:03:52The best way for THEM to find the shoals is to follow the dolphins.
0:03:59 > 0:04:02When the fish are far out to sea,
0:04:02 > 0:04:05the dolphins need great perseverance to track them down.
0:04:13 > 0:04:17The dolphins use their own form of sonar, sending out
0:04:17 > 0:04:21a stream of clicks and whistles, listening for returning echoes.
0:04:21 > 0:04:23CLICKING
0:04:25 > 0:04:27WHISTLING
0:04:35 > 0:04:38At last, they've found what they're looking for.
0:04:48 > 0:04:52Working as a team, the dolphins isolate a group of fish,
0:04:52 > 0:04:56and corral them into a tight ball close to the surface.
0:05:01 > 0:05:04The gannets can now make their move.
0:05:04 > 0:05:05LOUD CAWING
0:05:25 > 0:05:29Gannets can't dive deep, so they must rely on dolphins
0:05:29 > 0:05:32to keep the sardines near the surface.
0:05:32 > 0:05:34WHISTLING
0:05:45 > 0:05:47The feeding frenzy is short-lived.
0:05:47 > 0:05:50Most of the shoal escapes to the deep,
0:05:50 > 0:05:53and the hunters are left still hungry.
0:05:56 > 0:05:59It's December, the height of the southern summer,
0:05:59 > 0:06:01and the sardines have the advantage.
0:06:01 > 0:06:06With the shoals dispersed, life is hard for all the predators.
0:06:12 > 0:06:16But in six months' time, if conditions are right,
0:06:16 > 0:06:21the scene will be set for astonishing and sustained drama.
0:06:25 > 0:06:30For a few short weeks each winter, cold ocean currents
0:06:30 > 0:06:34can sweep great shoals of sardines up the coast.
0:06:34 > 0:06:39Trapped close to shore within this corridor of cool water,
0:06:39 > 0:06:44the fish are vulnerable and their predators will follow in droves.
0:06:45 > 0:06:49IF it happens, this will be the sardine run,
0:06:49 > 0:06:53one of nature's great events, unique to these shores of South Africa.
0:06:55 > 0:06:58But for this epic event to take place,
0:06:58 > 0:07:01many elements have to come together,
0:07:01 > 0:07:05and with our changing climate, they're less predictable every year.
0:07:07 > 0:07:12For the predators, the winter sardine run, if it happens,
0:07:12 > 0:07:16can make the difference between life and death.
0:07:16 > 0:07:22Dolphins rely on the easy hunting during the run to wean their calves.
0:07:22 > 0:07:24But the omens aren't good.
0:07:24 > 0:07:27Last year, the sardines didn't run at all.
0:07:32 > 0:07:34Gannets follow the same pattern.
0:07:34 > 0:07:38They have their chicks in summer, so they too leave the nest
0:07:38 > 0:07:40in time for the sardine run.
0:07:50 > 0:07:54This is Bird Island, just off the Eastern Cape -
0:07:54 > 0:07:57the biggest gannet colony in the world.
0:08:03 > 0:08:07No less than 100,000 breeding pairs come here every summer
0:08:07 > 0:08:09to have their young.
0:08:16 > 0:08:19These incredible numbers show the wealth of life
0:08:19 > 0:08:23the annual sardine run can support.
0:08:28 > 0:08:31They also show how many lives may be in jeopardy
0:08:31 > 0:08:34if the sardines don't run.
0:08:40 > 0:08:44Right now, the African summer is taking its toll.
0:08:44 > 0:08:48With temperatures soaring, and no cover on these exposed islands,
0:08:48 > 0:08:51the birds are in danger of overheating.
0:09:04 > 0:09:07The young are especially vulnerable.
0:09:07 > 0:09:10They have to be fed every day.
0:09:10 > 0:09:15Even with both parents taking turns, it's an exhausting task.
0:09:37 > 0:09:42In summer, the sardines are a long way out to sea.
0:09:44 > 0:09:48The birds fly hundreds of miles in search of a meal.
0:10:00 > 0:10:02Once they've sighted their target,
0:10:02 > 0:10:05they plunge from heights of 30 metres...
0:10:09 > 0:10:13..striking the water at 60mph.
0:10:24 > 0:10:29Every dive subjects them to enormous forces.
0:10:35 > 0:10:38The slightest miscalculation could be fatal.
0:10:45 > 0:10:49Gannets dive no deeper than ten metres, so once again,
0:10:49 > 0:10:53they rely on the dolphins to keep their prey near the surface.
0:10:54 > 0:10:58But with so much traffic, there's always the danger of a collision.
0:11:16 > 0:11:19This one has broken her neck.
0:11:22 > 0:11:25Her death will mean
0:11:25 > 0:11:29that back on the colony, her chick will probably starve.
0:11:32 > 0:11:36The rest make the long flight home with their catch.
0:11:38 > 0:11:41One partner stays on the island to guard their chick.
0:11:45 > 0:11:49The pair welcome each other with a ritualised greeting.
0:11:49 > 0:11:53They have a strong bond, and many couples mate for life.
0:12:15 > 0:12:19During the hours of daylight, the sardines stay deep
0:12:19 > 0:12:22in an attempt to avoid their predators.
0:12:27 > 0:12:32As the sun sets, the little fish themselves can begin to feed.
0:12:34 > 0:12:36They swim upwards
0:12:36 > 0:12:40to sieve the water for plankton, microscopic plants and animals.
0:12:54 > 0:12:59At daybreak, they sink once more into the safety of the deep.
0:13:13 > 0:13:18It's not just dolphins and gannets that rely on sardines.
0:13:23 > 0:13:27There are other, more mysterious predators.
0:13:39 > 0:13:42The Bryde's whale hardly breaks the surface to breathe,
0:13:42 > 0:13:46and never so much as shows a tail fluke.
0:13:52 > 0:13:57For a 15-metre whale, they can vanish with remarkable ease.
0:13:59 > 0:14:03We know little about these stealthy Leviathans,
0:14:03 > 0:14:05other than they are sardine hunters, too.
0:14:17 > 0:14:22Summer is a lean time for the Bryde's whale,
0:14:22 > 0:14:25as it is for all the predators.
0:14:30 > 0:14:33Sharks follow the same patterns,
0:14:33 > 0:14:36tracking the shoals offshore through the summer,
0:14:36 > 0:14:40waiting for the winter sardine run, when the hunting will be easier.
0:14:42 > 0:14:47But being cold blooded, they don't have the high energy demands
0:14:47 > 0:14:49of the whales, dolphins and gannets.
0:14:57 > 0:15:00All the predators have to endure the lean months,
0:15:00 > 0:15:03relying on the southern winter, in June,
0:15:03 > 0:15:05to bring a change in their fortunes.
0:15:08 > 0:15:15Now the changing seasons create a switch in the ocean currents.
0:15:15 > 0:15:17As summer gives way to autumn,
0:15:17 > 0:15:20the southerly flowing warm current weakens
0:15:20 > 0:15:25and cold Antarctic water pushes further north, nearer to land.
0:15:26 > 0:15:30The sardines are carried along by these cool waters
0:15:30 > 0:15:33and pushed closer to shore.
0:15:36 > 0:15:39If these ocean currents continue to change,
0:15:39 > 0:15:43the sardine run should be only three months away.
0:15:48 > 0:15:52It's time for the gannet chicks to leave the safety of their colony.
0:16:03 > 0:16:06Parents stop feeding their young when they're three months old.
0:16:06 > 0:16:09This forces the chicks to take to the sea.
0:16:12 > 0:16:17The young have enough fat reserves to survive for just ten days,
0:16:17 > 0:16:19and in this brief window,
0:16:19 > 0:16:23they must learn how to fly and hunt for themselves.
0:16:26 > 0:16:30This is the most critical time in a gannet's life.
0:16:30 > 0:16:33Failure will mean starvation.
0:16:45 > 0:16:48To prepare for their maiden flight, they test their wings
0:16:48 > 0:16:51and strengthen their flying muscles.
0:17:03 > 0:17:07Eventually, hunger drives them onwards and upwards.
0:17:25 > 0:17:29Some get up and away first time.
0:17:38 > 0:17:43But many don't make it past the crashing surf.
0:18:10 > 0:18:16Some bedraggled chicks struggle back to shore,
0:18:16 > 0:18:20but for others the pounding has been too much.
0:18:48 > 0:18:52Fewer than half of all the chicks on this colony
0:18:52 > 0:18:55survive their first three months of life.
0:19:13 > 0:19:18The coast of South Africa is an unforgiving place.
0:19:23 > 0:19:26The baby dolphins are still dependent on their mothers.
0:19:26 > 0:19:31They suckle for six months before they, like the young gannets,
0:19:31 > 0:19:33have to start fishing for themselves.
0:19:40 > 0:19:44There is such an abundance of fish during the sardine run
0:19:44 > 0:19:46that even the calves can catch some,
0:19:46 > 0:19:50and so begin to learn their hunting skills.
0:19:55 > 0:20:01But the sardine run might not even happen this year.
0:20:04 > 0:20:09For now, the dolphins will have to continue to scour the vast ocean.
0:20:29 > 0:20:34Back at the coast, other youngsters are getting ready to go it alone.
0:20:43 > 0:20:49Cape fur seals are also waiting for the sardines to come close to shore.
0:20:54 > 0:20:59But seals have a broad diet, so they can make the most of
0:20:59 > 0:21:03other feeding opportunities until the sardines come within range.
0:21:07 > 0:21:13Young seals are forced from the colony by the dominant males.
0:21:24 > 0:21:27Once they're cast out, the adolescents roam the coastline
0:21:27 > 0:21:29looking for food.
0:21:45 > 0:21:49They won't turn their noses up at a plump young gannet.
0:21:58 > 0:22:00Hungry seals patrol the surf,
0:22:00 > 0:22:05ready to pick off any birds that don't get airborne straight away.
0:22:05 > 0:22:11When the wind is light, the gannet chicks are stuck on the island.
0:22:18 > 0:22:22Surely they're safe here?
0:22:22 > 0:22:26But even on land, the seal is surprisingly fast on his flippers.
0:23:28 > 0:23:32In this one season, on this one colony alone,
0:23:32 > 0:23:35seals kill up to 10,000 fledglings.
0:23:37 > 0:23:41And as ever, it all comes down to sardines,
0:23:41 > 0:23:43for the seals are only after the fish
0:23:43 > 0:23:46within the stomach of their victims.
0:23:50 > 0:23:53For the young birds who do make it past the seals,
0:23:53 > 0:23:57there are fresh challenges; learning the skills of their parents.
0:24:02 > 0:24:06First, they have to find their quarry, the sardine shoals,
0:24:06 > 0:24:11and the best way to do that is to follow the expert trackers.
0:24:22 > 0:24:28They're hungry. It's been days since their parents last fed them.
0:24:37 > 0:24:42As the search goes on, the chicks are learning the most sophisticated
0:24:42 > 0:24:46survival technique of all; how to harness the expertise
0:24:46 > 0:24:48of another species.
0:24:56 > 0:25:00After a long search, the dolphins have found a small school of fish.
0:25:04 > 0:25:06They drive the sardines
0:25:06 > 0:25:10to the surface and within range of the young gannets.
0:25:10 > 0:25:14Now, quickly, they have to learn the art of the plunge dive.
0:25:20 > 0:25:22But there's a problem.
0:25:22 > 0:25:25The opportunistic seals have found the fish, too.
0:25:30 > 0:25:33The young gannets have a daunting choice; to risk
0:25:33 > 0:25:36diving with the enemy, or to starve.
0:25:37 > 0:25:41If they don't take their chances soon, there'll be nothing left.
0:25:54 > 0:25:58They're in luck. With sardines back on the menu,
0:25:58 > 0:25:59the seals ignore the gannets.
0:26:10 > 0:26:15As ever, the dolphins have done the hard work of rounding up the fish,
0:26:15 > 0:26:18and now a host of other predators take advantage.
0:26:20 > 0:26:25With the shoal diminishing by the second, competition is fierce.
0:26:25 > 0:26:29But there is still time for a mighty intruder.
0:26:43 > 0:26:47The Bryde's whale devours the entire ball of fish.
0:26:47 > 0:26:53Until the sardine run starts in earnest, these minor skirmishes
0:26:53 > 0:26:56are mere preludes to the main event.
0:26:56 > 0:27:00But winter is finally on the way.
0:27:00 > 0:27:03The cold current pushes further north.
0:27:03 > 0:27:07This cool water forces its way up the coast.
0:27:07 > 0:27:09If it continues to flow northwards,
0:27:09 > 0:27:13it will carry great shoals of sardines with it.
0:27:17 > 0:27:22The predators begin to gather, in anticipation of a feast.
0:27:29 > 0:27:33Sardines can't tolerate water above 20 degrees Centigrade,
0:27:33 > 0:27:37so unless the cool water penetrates further up the coast,
0:27:37 > 0:27:41the fish won't move and the annual run just won't happen.
0:27:42 > 0:27:47Perhaps climate change has made its mark here?
0:27:47 > 0:27:51The waters have stayed too warm, stalling the movement of fish.
0:27:51 > 0:27:55There hasn't been a sardine run for the past two years.
0:28:03 > 0:28:07The entire fleet is becalmed.
0:28:40 > 0:28:45A winter storm rolls in from the Antarctic, battering the Cape,
0:28:45 > 0:28:47bringing cold water.
0:28:59 > 0:29:03Driven by their hunger, gannets still try to hunt
0:29:03 > 0:29:05in these dangerous conditions.
0:29:11 > 0:29:14In fact, this wild weather is just what all
0:29:14 > 0:29:16the predators have been waiting for.
0:29:16 > 0:29:19For them, it's a perfect storm.
0:29:21 > 0:29:26It has pushed a narrow tongue of colder water up the coast.
0:29:26 > 0:29:31This chilly current carries wave after wave of sardines with it.
0:29:31 > 0:29:35Hemmed in by the land on one side and warm water on the other,
0:29:35 > 0:29:38the sardines are being drawn into a trap.
0:29:42 > 0:29:46Nature is playing a cruel trick on these unfortunate fish,
0:29:46 > 0:29:49as they'll get no benefit from their mass voyage.
0:29:51 > 0:29:54They're slaves to the cold ocean currents.
0:29:57 > 0:30:02More than 500 million fish are swimming towards disaster,
0:30:02 > 0:30:05and yet this is just a tenth of the sardine population.
0:30:05 > 0:30:08The run is on.
0:30:18 > 0:30:21Ahead, an ambush is being prepared.
0:30:25 > 0:30:27As the seas begin to calm
0:30:27 > 0:30:31the dolphins relocate the sardine shoals.
0:30:44 > 0:30:49As they track up the coast the pods unite, combining forces.
0:30:57 > 0:31:01They form super-pods of incredible numbers -
0:31:01 > 0:31:04up to 5,000 dolphins in one group.
0:31:10 > 0:31:14This is fast becoming one of the biggest groups of predators
0:31:14 > 0:31:16anywhere on the planet.
0:31:21 > 0:31:25The attackers spread out into wide hunting lines,
0:31:25 > 0:31:27stretching up to a mile across.
0:31:37 > 0:31:41Other divisions follow on - as ever, tracking the dolphins.
0:31:49 > 0:31:53Shadowing them all, the Bryde's whale.
0:32:02 > 0:32:06They're all heading in one direction, towards a place
0:32:06 > 0:32:08known as Waterfall Bluff.
0:32:15 > 0:32:20It's an arc in the coastline which interrupts the flow of currents,
0:32:20 > 0:32:22trapping the water in a swirling eddy.
0:32:24 > 0:32:27And the dolphins know that the massive shoals
0:32:27 > 0:32:30often get caught in this bottleneck.
0:32:40 > 0:32:45But these sardines have managed to avoid the trap.
0:32:47 > 0:32:50The first shoals have been carried well to the north
0:32:50 > 0:32:54of Waterfall Bluff, ahead of the dolphin super-pods.
0:33:02 > 0:33:06As the cool water is squeezed into an ever thinner band,
0:33:06 > 0:33:10closer to the shore, the shoals are forced up into the shallows.
0:33:21 > 0:33:26Only now do we get a real sense of the sheer volume of fish.
0:33:26 > 0:33:32This one shoal stretches along the coast for 15 miles.
0:33:38 > 0:33:42The water is 15 metres deep and packed with sardines
0:33:42 > 0:33:43from top to bottom.
0:33:46 > 0:33:52There could be more than 100 million fish in this single shoal alone.
0:33:52 > 0:33:56As long as the sardines are in such shallow water, they're beyond
0:33:56 > 0:34:00the reach of the dolphins, who won't follow for fear of stranding.
0:34:01 > 0:34:05And the gannets can't risk diving into such shallow water, either.
0:34:10 > 0:34:13But there are hunters who can follow.
0:34:13 > 0:34:16And they've arrived in their thousands.
0:34:18 > 0:34:19Sharks.
0:34:37 > 0:34:43Dusky, copper and ragged-tooth sharks encircle the sardines.
0:34:46 > 0:34:51But for the little fish, there's safety in such vast numbers.
0:34:51 > 0:34:56The sheer volume of sardines, the way they twist and turn in harmony,
0:34:56 > 0:34:58confuses the sharks.
0:35:03 > 0:35:06Without dolphins to round up the fish.
0:35:06 > 0:35:10these sharks have to find their own solution.
0:35:21 > 0:35:26They try to trap the fish against the water's surface.
0:35:30 > 0:35:34But this boiling water is mostly sardines escaping.
0:35:34 > 0:35:36Few are actually eaten.
0:35:48 > 0:35:53Tiny fish triumph over the marauding sharks.
0:36:04 > 0:36:10The sharks continue to harry the shoal, pushing it ever northwards.
0:36:20 > 0:36:24Back at Waterfall Bluff, the dolphins and gannets are waiting
0:36:24 > 0:36:29for the next pulse of sardines to come up from the south.
0:36:29 > 0:36:32If there is another shoal, this kink in the coastline
0:36:32 > 0:36:34is the perfect place to ambush them.
0:36:34 > 0:36:40But if the fish don't come, these hungry predators face a long journey
0:36:40 > 0:36:42all the way back to the Cape.
0:36:46 > 0:36:50To the north, the survivors of the shark attack
0:36:50 > 0:36:53are nearing the end of their run at the beaches around Durban.
0:36:57 > 0:37:00These seem like the lucky ones.
0:37:00 > 0:37:04On their epic journey, they've evaded an army of hunters.
0:37:06 > 0:37:11But one final, unexpected, predator lies in wait.
0:37:23 > 0:37:28Fishermen can only net the sardines once they've swum this far north,
0:37:28 > 0:37:30within easy reach of the shore.
0:37:33 > 0:37:37Last year, no sardines were seen on this coast.
0:37:37 > 0:37:39So far this winter, the fishermen have landed
0:37:39 > 0:37:44only 50 tonnes, barely a tenth of what they'd expect in a good year.
0:37:51 > 0:37:55That's how unpredictable the sardine run has become.
0:38:07 > 0:38:10After such a long and hazardous voyage,
0:38:10 > 0:38:14it's a sad end for these sardines.
0:38:23 > 0:38:28At Waterfall Bluff, the dolphins and gannets have had to bide their time.
0:38:33 > 0:38:36After missing the first shoal, these predators are relying
0:38:36 > 0:38:42on the currents to sweep another big pulse of sardines up the coast.
0:38:44 > 0:38:46Now another great shoal
0:38:46 > 0:38:50is on the way, and it's heading straight for Waterfall Bluff.
0:38:57 > 0:39:01Trapped between the shore on one side and warm water on the other,
0:39:01 > 0:39:05these fish are swimming straight towards the enemy.
0:39:17 > 0:39:20The sardines fall back on their
0:39:20 > 0:39:26instinctive defence, swarming into a huge mass that confuses a predator.
0:39:36 > 0:39:42But the dolphins have a strategy that turns this to their advantage.
0:39:45 > 0:39:49Working together, they separate off a pocket of sardines.
0:39:53 > 0:39:58In smaller numbers, the shoaling defence now works against them.
0:39:59 > 0:40:04The dolphins corral the bait ball and herd it to the surface.
0:40:17 > 0:40:20This is what the other hunters have been waiting for.
0:40:23 > 0:40:26Now the sardines are within range of the gannets.
0:40:48 > 0:40:51The bait balls form and reform,
0:40:51 > 0:40:54seldom lasting longer than a few minutes each.
0:41:18 > 0:41:23The sharks pile in, taking advantage of the dolphins' hard work.
0:41:30 > 0:41:32The predators ignore each other.
0:41:32 > 0:41:34There's only one victim here -
0:41:34 > 0:41:40the millions of tasty little fish they've been stalking for so long.
0:42:01 > 0:42:03Young gannets join the frenzy.
0:42:03 > 0:42:07In just six months, they have become superb aerial hunters.
0:42:16 > 0:42:22Time after time, the dolphins round up another shoal for destruction.
0:42:45 > 0:42:48Frantically, the little fish try to get away
0:42:48 > 0:42:50from the seething surface of the water,
0:42:50 > 0:42:54to dive beyond the range of the gannets.
0:42:57 > 0:43:01Now, something truly astonishing happens.
0:43:04 > 0:43:08Diving takes the gannets down to ten metres.
0:43:09 > 0:43:14Then the aerial squadrons become shoals of swimmers,
0:43:14 > 0:43:17as they pursue the fish down to 20 metres.
0:43:21 > 0:43:25Sardines join with their predators in a beautiful,
0:43:25 > 0:43:28yet macabre, underwater ballet.
0:43:28 > 0:43:31There's little chance of escape for these fish.
0:44:11 > 0:44:15The stage is set for the biggest predator of all.
0:44:23 > 0:44:28The Bryde's whale takes in 10,000 fish in one giant mouthful.
0:44:32 > 0:44:37But this time around, there are plenty of sardines for all.
0:44:45 > 0:44:50Each hunter amongst these millions plays its part in the drama
0:44:50 > 0:44:53and each is dependent upon the other.
0:45:06 > 0:45:09The annual spectacle of the sardine run
0:45:09 > 0:45:14is the greatest gathering of predators on the planet.
0:45:20 > 0:45:24It's surely one of nature's great events.
0:46:15 > 0:46:19Then, almost as quickly as it began,
0:46:19 > 0:46:21it's over.
0:46:23 > 0:46:26As the brief winter comes to an end,
0:46:26 > 0:46:31warm currents flowing south displace the corridor of cool water.
0:46:35 > 0:46:38Despite the massacre,
0:46:38 > 0:46:42more than half of all the sardines swept up on the great run survive.
0:46:46 > 0:46:48As the currents switch,
0:46:48 > 0:46:51the fortunate ones make good their escape.
0:46:54 > 0:46:58From here, they'll follow deep water currents,
0:46:58 > 0:47:01hitching a ride back to the cool waters of the Cape.
0:47:06 > 0:47:12The Bryde's whale melts away to resume its secretive life,
0:47:12 > 0:47:15somewhere out in the big blue.
0:47:20 > 0:47:22The dolphin super-pods break up
0:47:22 > 0:47:26and begin their long trek back to the Cape.
0:47:31 > 0:47:33Gannets too head south.
0:47:42 > 0:47:45As Waterfall Bluff falls quiet once more,
0:47:45 > 0:47:48no-one can say whether this spectacular event
0:47:48 > 0:47:52will be repeated here in years to come.
0:48:00 > 0:48:04The sardine run may be unique to the coast of South Africa,
0:48:04 > 0:48:10but it's a vivid reminder of the riches our oceans still support.
0:48:37 > 0:48:41The amazing bait balls that characterise the sardine run
0:48:41 > 0:48:43are short-lived and very hard to find.
0:48:43 > 0:48:46Filming them was to turn into a two-year mission
0:48:46 > 0:48:48for the underwater team.
0:49:00 > 0:49:02To film the feeding frenzies,
0:49:02 > 0:49:05the team would need three key elements to come together -
0:49:05 > 0:49:07a huge shoal of sardines,
0:49:07 > 0:49:09the right mix of predators,
0:49:09 > 0:49:13and water clear enough to be able to see the action.
0:49:16 > 0:49:20The most important element to start with was seeing underwater
0:49:20 > 0:49:22and at the beginning of the first season,
0:49:22 > 0:49:27it wasn't looking good for underwater cameraman Didier Noirot.
0:49:27 > 0:49:31It looks like dirty water but I'm going to check anyway to be sure.
0:49:35 > 0:49:38Didier was Jacques Cousteau's underwater cameraman
0:49:38 > 0:49:40for more than a decade.
0:49:40 > 0:49:43He knows that the sardine run is very unpredictable
0:49:43 > 0:49:46and that some years it never happens at all.
0:49:49 > 0:49:51The predators were gathering,
0:49:51 > 0:49:54but the ocean currents weren't bringing any sardines.
0:49:56 > 0:50:01It wasn't a good start to the first season's filming.
0:50:03 > 0:50:05What's it like?
0:50:05 > 0:50:08No vis. No visibility.
0:50:10 > 0:50:14And the murky water held further risks.
0:50:14 > 0:50:17Poor vis, you don't see what's coming.
0:50:17 > 0:50:21So it's not that we are scared of all the sharks,
0:50:21 > 0:50:26but we notice that accidents, people get bitten always in dirty water...
0:50:26 > 0:50:28So why should we take the risk?
0:50:28 > 0:50:33We go in dirty water to make bad pictures and get bitten by sharks.
0:50:33 > 0:50:35It's not worth.
0:50:35 > 0:50:38I'd rather stay dry!
0:50:41 > 0:50:44After 20 days at sea with no sign of sardines,
0:50:44 > 0:50:48the crew kept themselves busy with some sound recording for the film.
0:50:50 > 0:50:54I didn't take my mask, you see, so I don't intend to dive.
0:50:56 > 0:50:59The team developed some ingenious techniques
0:50:59 > 0:51:03to get microphones close to the dolphins and gannets
0:51:03 > 0:51:05that were also waiting for sardines.
0:51:05 > 0:51:11So what we're doing today is trying a radio mic and a Frenchman...
0:51:11 > 0:51:13DIDIER MUTTERS OVER MICROPHONE
0:51:13 > 0:51:17The problem is... he doesn't know when to stop talking.
0:51:17 > 0:51:21It's the quietest we've had him for days but he still rabbits on.
0:51:21 > 0:51:25MUTTERING CONTINUES
0:51:25 > 0:51:28No-one was prepared for what happened next.
0:51:30 > 0:51:33The thing is, these aren't waterproof at all.
0:51:33 > 0:51:35Shark... SHARK, SHARK! QUICK, QUICK!
0:51:35 > 0:51:37- GO, GO!- QUICK! QUICK!
0:51:38 > 0:51:40ENGINE ROARS INTO LIFE
0:51:48 > 0:51:53He bit me. Big copper... is late, is murky water...
0:51:53 > 0:51:55We cannot stay there too long, you see.
0:51:59 > 0:52:03- Did he come right underneath you? - No, he bit my fins. I kick.
0:52:03 > 0:52:07- Seriously?- Yeah! I told you, there are sharks, so come and fetch me!
0:52:09 > 0:52:12The sharks were definitely about
0:52:12 > 0:52:18but the first season ended without Didier seeing any sardines.
0:52:22 > 0:52:25At the beginning of the second year the pressure was on,
0:52:25 > 0:52:27but things were looking up.
0:52:30 > 0:52:33With the help of aerial spotter, Eric Webber,
0:52:33 > 0:52:37Didier and the team could search a greater stretch of ocean.
0:52:40 > 0:52:42For the first time in three years,
0:52:42 > 0:52:46a huge slick of fish had been swept up the coast.
0:52:48 > 0:52:52The sardine run was well and truly on.
0:52:53 > 0:52:55And it was down to the eye in the sky
0:52:55 > 0:52:59to get Didier into the heart of the action.
0:52:59 > 0:53:03- RADIO:- We've got thousands of sharks approximately 200 metres off shore.
0:53:03 > 0:53:07You guys make you way there, you're mad enough to go into the water,
0:53:07 > 0:53:11I'll talk you on. It looks good - sharks and sards all over the place.
0:53:11 > 0:53:16We are in the area. Didier wants the highest concentration of sharks.
0:53:16 > 0:53:19Could you please guide us onto that area?
0:53:19 > 0:53:22Come 20 degrees left, you've got 40 metres to run,
0:53:22 > 0:53:26I'm going to put you in the front of the sards...
0:53:26 > 0:53:30Ten seconds to run, divers ready. Nine, eight,
0:53:30 > 0:53:32seven, six,
0:53:32 > 0:53:33five...
0:53:33 > 0:53:36Divers ready? Four,
0:53:36 > 0:53:38three, two...
0:53:38 > 0:53:40one, go, divers away!
0:53:46 > 0:53:49The great tide was indeed living up to its name.
0:53:51 > 0:53:54At last, Didier had some action to film.
0:53:54 > 0:53:58He had good visibility and sardines in abundance.
0:54:02 > 0:54:04But without dolphins around,
0:54:04 > 0:54:07the feeding frenzies just weren't happening.
0:54:07 > 0:54:12The sharks were unable to feed on the vast walls of fish
0:54:12 > 0:54:15and despite their impressive numbers,
0:54:15 > 0:54:18they were surprisingly wary of Didier.
0:54:18 > 0:54:21No. Very quiet, moving slowly.
0:54:21 > 0:54:24They are the lords of the sea, you know?
0:54:24 > 0:54:26There was no frenzy, no attack.
0:54:26 > 0:54:30I think they are getting prepared for the big action.
0:54:30 > 0:54:34Didier had yet to even see a big bait ball
0:54:34 > 0:54:39and there was only one week left for all the elements to come together.
0:54:39 > 0:54:43Clean water, lots of sardines and just the right mix of predators.
0:54:43 > 0:54:49And if there was one place to find it, it was Waterfall Bluff.
0:54:49 > 0:54:53Huge numbers of predators were starting to gather.
0:54:55 > 0:54:59This was the most action the crew had seen in two years
0:54:59 > 0:55:03and, again, it was down to Eric to put them on it.
0:55:04 > 0:55:06- RADIO:- Joker, this is Raven,
0:55:06 > 0:55:10we've got some major activity here, just off Mkambati.
0:55:10 > 0:55:13They were into the last week of filming
0:55:13 > 0:55:15and the pressure was showing.
0:55:15 > 0:55:17Yeah, this looks very, very good.
0:55:17 > 0:55:20At two o'clock, just here,
0:55:20 > 0:55:23but it's moving quite fast cos the dolphins are chasing it.
0:55:23 > 0:55:26- Slowly... RADIO:- Right 90. Go right 90 degrees.
0:55:26 > 0:55:31This is tricky, getting us onto the bait ball without breaking it up.
0:55:31 > 0:55:33INAUDIBLE DIRECTIONS ON RADIO
0:55:35 > 0:55:39Hey, hey! Ridden, over the bait ball. Just stop.
0:55:39 > 0:55:42- RADIO:- Joker, I think you've screwed that up.
0:55:42 > 0:55:47Too far. We don't get there. Move the boat, to the right!
0:55:48 > 0:55:51Below Eric...where's Eric?
0:55:51 > 0:55:54We shall go outside there.
0:55:56 > 0:55:59Now we have to go fast and to think fast!
0:55:59 > 0:56:02On the second to last day of filming,
0:56:02 > 0:56:05Didier finally got his chance.
0:56:05 > 0:56:06OK, Didier?
0:56:10 > 0:56:15Years of work had gone in to putting Didier on the front line.
0:56:15 > 0:56:17Now it was down to him.
0:56:24 > 0:56:26After 90 days of filming,
0:56:26 > 0:56:30he had less than an hour in which to fulfil his dream -
0:56:30 > 0:56:33to film a bait ball in perfect conditions.
0:56:55 > 0:56:56Didier was, at last,
0:56:56 > 0:56:59amongst the greatest gathering of predators on the planet.
0:57:05 > 0:57:09He'd managed to get closer than anyone to the feeding frenzy,
0:57:09 > 0:57:11without becoming part of it.
0:57:16 > 0:57:20Ahh! Today was the day. We just found a bait ball.
0:57:20 > 0:57:23We were looking for... months, years,
0:57:23 > 0:57:25and we finally found it.
0:57:26 > 0:57:30Only one problem - the sharks were too much aggressive!
0:57:30 > 0:57:32We were very...
0:57:32 > 0:57:34We got bumped a few times by sharks
0:57:34 > 0:57:39and that was just a bit, you know, serious.
0:57:40 > 0:57:43All that action came and that was just an amazing spectacle -
0:57:43 > 0:57:45all those birds diving together...
0:57:45 > 0:57:47Bom! Bom! Bom! Bom!
0:57:47 > 0:57:50Like real cannon explosion...
0:57:51 > 0:57:54And all those sharks under, following...
0:57:54 > 0:57:56and the dolphins, hey,
0:57:56 > 0:57:59that was just magical, magical.
0:57:59 > 0:58:00Phew!
0:58:02 > 0:58:04The feeding frenzy they filmed that day
0:58:04 > 0:58:07ended as quickly as it had begun.
0:58:07 > 0:58:09After two long years,
0:58:09 > 0:58:12Didier and the crew had managed to be
0:58:12 > 0:58:15in just the right place, at just the right time,
0:58:15 > 0:58:18for one of our ocean's greatest events.
0:58:45 > 0:58:48Subtitles by Red Bee Media Ltd
0:58:48 > 0:58:51E-mail subtitling@bbc.co.uk