Nature's Great Events E02 - The Great Salmon Run
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00:00The power of the sun drives the seasons, transforming our planet.
00:13Vast movements of ocean and air currents bring dramatic change throughout the year.
00:23And in a few special places, these seasonal changes create some of the greatest wildlife
00:29spectacles on Earth.
00:39Here on the western coast of North America, in the spring of each year, one of the Earth's
00:44greatest travellers comes home.
00:49Over half a billion salmon in the Pacific Ocean start on a 3,000-mile journey, returning
00:55to spawn in the rivers where they were born.
01:04Travelling deep into the continent, these fish will not only provide food for millions
01:09of animals.
01:15They will also bring life to one of the richest habitats on Earth.
01:32The coast of British Columbia and Alaska is rimmed by spectacular mountains.
01:58Although it will be months before the salmon enter the rivers below these frozen peaks,
02:04one species that has spent the winter sleeping up here is already anticipating their return.
02:15In January, snug in their dens, the females have given birth, and now the family is beginning
02:23to stir.
02:42Grizzly bears.
02:48Whether the cubs will live or die depends largely on one key event, the salmon run.
02:55For the next five months, the bears will be focused on making their appointment with the
02:59returning salmon.
03:20Surviving the first year is hard.
03:24Half of all grizzly cubs don't make it.
03:42Throughout Alaska and British Columbia, thousands of bear families are emerging from their winter
03:48sleep.
03:51There is nothing to eat up here, but the conditions were ideal for hibernation.
03:59Lots of snow in which to dig a den.
04:06To find food, mothers must lead their cubs down to the coast where the snow will already
04:12be melting.
04:19But getting down can be a challenge for small cubs.
04:49These mountains are dangerous places, but ultimately, the fate of these bear families,
04:59and indeed that of all bears around the North Pacific, depends on the salmon.
05:06Right now, those salmon are more than 2,000 miles away.
05:17After four years at sea, half a billion Pacific salmon are going home, back to fresh water,
05:24to lay their eggs in the rivers where they themselves were hatched.
05:40How the salmon manage to find their way back home across the open ocean is still largely
05:46a mystery.
05:49It has only recently been discovered that a salmon's brain contains small particles
05:54of iron that, like a compass, help it steer the magnetic lines of the earth, showing them
06:01exactly where to go.
06:23For many of these salmon, that destination is here, along the western coast of North
06:28America, in British Columbia.
06:38They're making their way back to their birthplace, in one of its many freshwater rivers and streams.
06:49Here, amongst the network of lakes and waterways, lies the largest expanse of temperate rainforest
06:55left in the world.
07:00It stretches from southern British Columbia to Alaska.
07:12It's one of the most fertile landscapes on the planet.
07:29The temperate rainforest supports even more life than its tropical counterpart.
07:40For thousands of years, salmon have returned to this country because of the abundance of
07:45one element, fresh water.
08:14This is some of the purest water in the world, thanks to these forests.
08:34Where the forests are still undisturbed, the soil, held by millions of tree roots, filters
08:40the water, keeping the rivers flowing clean and pure.
08:55In May, grizzly bears come down to the coast to find something to eat while they await
09:01the arrival of the salmon.
09:05This is where spring arrives first.
09:15The cubs, still feeding on nothing but their mother's milk, have grown considerably.
09:26But it has been six months since their mother had anything to eat.
09:41Now they need other food, and the search for it can lead them into danger.
09:51Some males will try to kill cubs.
09:57The breeding season has begun, and big males are here looking for females.
10:21But at least there's something to eat here, even if it's only grass and sedges.
10:29These greens, in fact, can keep them going for months, but they will need something more
10:34nutritious if they're to put on enough fat to enable them to survive the next winter.
10:45In some places along the coast, bears find much richer food.
10:54It's buried, but bears have an extremely acute sense of smell, and can sniff out a meal even
11:00if it's beneath the wet sand.
11:09Clams.
11:15It's not only bears that are drawn to the coast in search of food.
11:27There are more than 2,000 grey wolves in the great forest.
11:36They leave their cubs in the tidal areas while they hunt.
11:48This wolf is the pup's eldest brother.
11:51He's babysitting while the adults are away hunting.
11:54He doesn't have any food for the cubs, so they eat whatever they can find, even chewing
11:59the barnacles off the rocks.
12:10They, like the bears, are awaiting the arrival of the salmon.
12:24The adults return and find an intruder.
12:29A hungry bear has wandered into their patch.
12:37Coastal wolves will often kill and eat small bears.
12:50But this bear is very big.
12:59Eventually, they decide that this one is just too big.
13:27By July, the bears are all getting very hungry indeed.
13:32And still the salmon are not here.
13:44And then, after two months of travelling across the open ocean, the salmon reach the coast.
13:56As they near the shore, they begin to smell fresh water.
14:03There are thousands of rivers flowing into the sea, and the salmon have to find the particular
14:13one that will lead them to their birthplace.
14:20They have a truly extraordinary sense of smell.
14:26They can distinguish a single drop from their home river amongst two million gallons of
14:32seawater.
14:38As they detect the waters of home, they converge into the narrow fjords, which act as underwater
14:44corridors.
14:48But other creatures also know these corridors.
14:56Killer whales.
14:57They eat a lot of salmon.
15:08And so do steller's sea lions.
15:26Salmon sharks are here too, specifically to feed on salmon.
15:37But there is one predator that they can never see coming.
15:45The bald-headed eagle.
16:16Once past these coastal predators, there is little to prevent them from reaching their
16:39home river.
16:40It's now late July, and the salmon are poised at the edge of their inland realm.
16:52In the estuaries of the larger rivers, all five species of Pacific salmon mingle together.
16:59Pink, chum, coho, sockeye and chinook.
17:10The drive to get into the rivers is strong.
17:14Their eggs will only survive in fresh water.
17:24In late July, however, the water level is often too low for the first salmon to enter
17:30the smaller rivers.
17:39That doesn't stop them trying.
17:45But the very water that has drawn them back home will eventually kill them.
17:54As their kidneys and other organs adjust to the sudden lack of salt water, they stop
18:00eating and even drinking.
18:04So the energy stored in their bodies is all they have to power their swim upriver and
18:09spawn.
18:12However, the salmon in the smaller streams have a more immediate problem.
18:22The low water has stopped them before their journey upstream can even begin.
18:35But their coast, every year, is swept by great storms.
18:43In the skies above the North Pacific, a huge eddy is forming.
18:50It moves towards the coast and the high coastal mountains.
19:17The clouds are driven up and over this massive barrier and they drop their load of water.
19:48The Great Forest gets up to ten feet of rainfall a year.
20:04Bears have thick coats and the heavy rain doesn't seem to bother them at all.
20:18The steep rocky mountains funnel the rainwater into the rivers and levels quickly rise.
20:36This is what the salmon have been waiting for.
20:48The first wave of travellers advance upstream.
20:58No sooner do they start than they're faced with another challenge.
21:08But six million years of evolution have prepared the salmon well.
21:18Their bodies are solid muscle and perfectly streamlined.
21:42Clearing these falls for a salmon is like a human being jumping over a four-storey building.
22:01In many of these falls, however, the salmon face more than just water.
22:09The bears know that this is where they can get the first proper meal of the season.
22:18But it's not easy.
22:23There is an art to catching a leaping salmon.
22:30And this young bear hasn't yet acquired it.
22:39This is what salmon were born to do.
22:51They're driven to get up these rivers to their spawning grounds.
22:57Their parents made it up here and nothing short of death will stop them from repeating that journey.
23:05They're trying to get to the exact stretch of gravel where they hatched.
23:14Some lucky ones may only have to go a few miles inland, but others are faced with a truly daunting journey.
23:27The farthest that salmon have been known to swim upriver is 2,000 miles.
23:35Summer rains can be short.
23:40And when they stop, the water levels in many of the rivers along the coast drop quickly.
23:48The first salmon in the rivers are once again trapped by shallow water.
23:53And worse, they're in bear country now.
23:59In early August, mother bears begin to patrol the rivers looking for fish.
24:05Like this one, they're usually skinny and starving.
24:18She and her cubs have eaten nothing but plants since they emerged from their den.
24:24They're in desperate need of a proper meal.
24:28Bears of all ages and experience come to the rivers to look for salmon.
24:38The first fish of the season, however, are hard to catch.
24:45This young bear is still learning how to do it.
24:49Step number one is spotting a salmon.
24:54A higher perspective usually helps.
25:01In these early days, fish are few and far between.
25:08And when they do appear, they're moving very fast.
25:24The salmon are also very fast.
25:44The salmon also have lots of places to hide.
25:47The rivers are only shallow in short stretches,
25:50and they can quickly shoot across them and escape into the deep pools.
26:02This mother and her cubs are going to have to wait a little longer
26:06for the conditions to change before they can get the meals they so badly need.
26:12But for the salmon, these deep-water refuges are becoming prisons.
26:25It may be weeks before it rains again, and they can move on.
26:36Their bodies are still in the water,
26:40their bodies are now beginning to change.
26:44As their sex hormones stimulate the production of eggs and sperm,
26:49their skin changes colour.
26:54Some develop a humped back and a hooked nose.
27:00All these changes use up precious energy.
27:04The longer the fish wait in these pools,
27:06the less likely they will be able to complete the journey to their spawning grounds.
27:16The mother bear and her cubs, finding little in the shallows,
27:19now try their luck in the deeper salmon-filled pools.
27:30The salmon are easy enough to see.
27:36With so many fish here, this young bear should surely be able to catch something.
27:47But finding the salmon is only part of the problem.
27:53Bears must pin a salmon to the stream bed in order to catch it.
27:57Not easy in deep water.
28:01Older bears know that it's almost impossible to get a meal this way.
28:09But while the salmon here may be relatively safe from the bears,
28:13they're not out of danger.
28:20The late summer sun is warming the water,
28:23so that levels are dropping and the amount of dissolved oxygen is decreasing.
28:31The time spent in these worsening conditions is beginning to show.
28:42The experienced bears show the youngsters what to do.
28:47Catching live salmon in these pools may be difficult,
28:50but there are dead ones for the taking if only the bears can reach them.
29:01The problem is that most bears don't like to get their ears wet.
29:20However, the old bears know a trick or two.
29:30It just needs a little fancy footwork.
30:01This year, the water levels are particularly low,
30:05and by September, the salmon are in real trouble.
30:11In the confined, oxygen-poor water,
30:14there is an increased risk of parasites and infections.
30:22In some years, these conditions can get so bad
30:25that most of the salmon die before they even reach the spawning grounds.
30:36What they need is more rain, and soon.
30:44Luckily, this year, the autumn rains arrive on time.
30:56The salmon can set off once again.
31:02However, so much rain brings different challenges.
31:08The water levels are so high,
31:11that the bears can't get their ears wet,
31:14and the salmon can't get their ears wet,
31:17and the bears can't get their ears wet.
31:21However, so much rain brings different challenges.
31:31The fish now have to battle against powerful torrents.
31:36But the salmon know how to turn this swift, turbulent water
31:40to their own advantage.
32:06Scarcely beating their tails,
32:08they manage to propel themselves forward
32:11by using the energy of the water,
32:13much as a sailboat does when tacking into the wind.
32:36But that doesn't mean there will be no further problem
32:39in reaching the spawning grounds.
33:06This is going to be the end of the road for a lot of salmon.
33:13These bears are really hungry.
33:15They haven't tasted salmon for ten months,
33:18and the big males battle for the best fishing spots.
33:28The longer the salmon take over their journey upstream,
33:32the weaker they become.
33:37And these falls present them with their biggest challenge yet.
33:42Although the falls aren't very tall,
33:45the bears hold the high ground.
33:49The salmon make short, exploratory leaps
33:52to see where the bears are.
34:03But they don't always get it right.
34:11This mother bear has been waiting months for this moment.
34:17Competition is fierce for these first salmon,
34:20even between a mother and her own cubs.
34:25The first salmon are a bit nervous.
34:27Competition is fierce for these first salmon,
34:30even between a mother and her own cubs.
34:38More and more fish arrive at the foot of the falls.
34:42Eventually, they have to go for it, regardless of the danger.
35:12But numbers are on their side.
35:35But numbers are on their side.
35:37For every salmon that gets caught,
35:39hundreds make it past the bears.
36:10By early September,
36:12the salmon have almost reached their spawning grounds,
36:16that one particular patch of gravel where they hatched four years ago.
36:26The salmon have now travelled far inland
36:29and can be found from California to the Arctic Ocean,
36:33across a fifth of the entire globe.
36:39The entire continent of North America.
36:59But the journey has taken a heavy toll.
37:03For every thousand that hatched, only four managed to return.
37:10And even for those salmon that have made it back,
37:14there are still more dangers.
37:16They have finally reached the end of their road
37:19and are so tired and battered that they're easy prey.
37:23The advantage is fully to the bears now.
38:10BIRDS SQUAWK
38:35The bears are spoiled for choice.
38:40BIRDS SQUAWK
38:42In the best spawning areas,
38:44there are thousands of salmon in every mile of river.
38:51The bears here will gorge themselves for the next two months
38:55and the mothers with their cubs can now gain the weight they will need
38:59if they're to make it through the coming winter.
39:09BIRDS SQUAWK
39:14The salmon are so abundant that even the little cub is having a go.
39:29He's caught a female pink, the smallest of the salmon species.
39:35He's already learning the skills he will need to survive as an adult.
39:46But he's got a little way to go yet.
39:53Although the salmon are now at the mercy of the bears,
39:56they will not leave this place.
39:58Their nature impels them to lay their eggs where they themselves were born.
40:04BIRDS SQUAWK
40:12Even though the bears eat their fill,
40:14there are so many salmon that most will survive to spawn.
40:24The sockeye salmon's brilliant colour signals that they're ready to breed.
40:30Males battle with each other for position behind the females.
40:43The female digs out a shallow scoop as a nest.
40:48BIRDS SQUAWK
40:58The male nestles up against the female, stimulating her to release her eggs.
41:06When she's ready, she lowers herself over the nest.
41:10She begins to turn out her eggs
41:12and the male releases a cloud of sperm into the water.
41:17BIRDS SQUAWK
41:34These salmon are the lottery winners,
41:37the lucky ones that have succeeded in returning here to spawn.
41:42But there are enough of them to seed the next generation.
41:47BIRDS SQUAWK
41:53The spawning season is a time of extreme abundance,
41:57for in the course of ensuring their own survival,
42:00the salmon provide food for a horde of other creatures.
42:04BIRDS SQUAWK
42:11These bone-apart gulls are collecting one of the season's great delicacies,
42:16salmon eggs.
42:30BIRDS SQUAWK
42:38For the bears, the salmon spawning season is the pinnacle of the year.
42:47BIRDS SQUAWK
42:49But for the salmon, it's the pinnacle of their entire lives.
43:01All that have reached it will end their days
43:04in the very place where they began them.
43:17The wear and tear of their long journey is now showing.
43:27Their bodies have been deteriorating for weeks,
43:30and with this last act of reproduction, they are finally spent.
43:46BIRDS SQUAWK
43:56But even in death,
43:58the salmon continue to benefit the animals of the forest.
44:07The mother and her cubs will continue to fatten themselves on the carcasses
44:12until they're ready to head back up the mountain to den in November.
44:22Why Pacific salmon have to die after they reproduce
44:26is not clearly understood.
44:29Atlantic salmon don't.
44:31They return year after year to spawn.
44:34But the Pacific salmon's decaying bodies nourish the rivers,
44:38providing abundant food for their growing eggs.
44:43And that is what it has all been about for the salmon.
44:48All their trials and tribulations have ensured that the baby salmon,
44:52when they emerge from these beautiful orange globes,
44:56will have everything they need to begin this incredible journey all over again.
45:03BIRDS SQUAWK
45:11But the legacy of the salmon extends far beyond the rivers and streams.
45:19They are at the heart of a massive network of life.
45:25There are more than 200 species in the great forest alone,
45:29plants and insects, birds and mammals that depend on the salmon.
45:40It's possible that Pacific salmon,
45:42between their time out at sea and their time inland,
45:45feed more life than any other animal species on the planet.
45:54And there is one more beneficiary of the salmon's legacy.
45:59BIRDS SQUAWK
46:05The fish are a unique link between the ocean and the forest.
46:15Born in fresh water, they live their life in the sea,
46:19and there gather nutrients with which they build their bodies.
46:30Now, scattered by feeding bears and wolves,
46:34the last bequest of these salmon is to the forest.
46:48Nitrogen, carbon and phosphorus that was gathered in the ocean
46:52is now released from their decaying bodies.
47:00Providing the nutrients that enable these trees,
47:05Sitka spruce,
47:08red cedar
47:11and western hemlock,
47:14to grow to such prodigious heights.
47:21It's now known that 80% of the nitrogen in these coastal forests
47:25where the salmon spawn comes from the sea,
47:29carried in the bodies of the returning fish.
47:37The trees may be growing hundreds of miles from the ocean,
47:41but they're still nourished by its richness.
47:48The rivers of the great forest,
47:50like the veins and arteries of an animal,
47:53carry its lifeblood, the Pacific salmon, throughout.
48:05And no animal relies on them more than the grizzly bear.
48:15Thanks in large part to the abundance of the salmon run,
48:19these cubs have survived their first and most difficult year.
48:25The bears will sleep easy each winter,
48:28as long as the Pacific salmon are able to continue their epic run.
48:34One of nature's great events.
48:50The Great Salmon Run
49:03In making The Great Salmon Run,
49:05filmmaker Geoff Turner wanted to discover
49:08exactly how grizzly bears caught salmon underwater.
49:20But his quest was to take him deeper into the world of the grizzly
49:25than he had ever imagined.
49:35The first challenge that Geoff and the team faced
49:38was to get their latest high-definition camera systems
49:42into the wilds of British Columbia.
49:44This is modern-day wildlife filmmaking.
49:46You can't go anywhere without about half a tonne of gear.
49:50It's very discreet. Animals don't notice that at all.
49:54Geoff has more than 20 years' experience of filming grizzlies
49:58and knows how to work with them in the wild better than anyone.
50:03I was just talking to Justin.
50:05He was telling me he just came back from a shoot in Indonesia.
50:10He said he had 15 porters.
50:13I think we must be doing something wrong.
50:18Geoff knows that the only way to film wild grizzlies
50:21is with a small crew and a very sensitive approach.
50:27In order to get the shots he wanted,
50:29he used a new digital camera in a specially built underwater housing
50:33that he could set up close to the fishing bears without disturbing them.
50:39Getting the camera in place can be tricky, however.
50:42Experience has taught him how to put them at their ease
50:45with just the right tone of voice.
50:47Hey, bear. How you doing, eh?
50:49I'm going to scare some fish up there for you.
50:52That's a good bear. I won't bother you. It won't be long.
51:03This one, you need six hands.
51:05The wild bears seemed intrigued by this visitor to their river.
51:09You guys are excited about this as I am.
51:12OK, and now to the left.
51:14What Geoff was hoping to capture
51:16was a shot of bears catching salmon from both above and below water.
51:22He needed to operate the camera from a distance
51:24so that the bears would be so relaxed they would continue fishing.
51:30But that meant connecting the camera to his computer
51:33using fibre-optic cable.
51:35If they come through here, you know, catching it.
51:38And all that cable in the river proved too much of a temptation
51:42for one particularly mischievous young bear,
51:45a situation that called for some firm bear talk from Geoff.
51:49Hey! Hey! Drop it! Drop it!
51:53Yeah, yeah, yeah!
52:00You guys can't bite the cable!
52:03Jeez!
52:05Oh!
52:07Luckily, the camera was still working.
52:11But Geoff soon realised that the salmon were avoiding the shallow waters
52:15and he wasn't getting the shots he wanted.
52:19The bears were being drawn to the deep pools
52:22where the salmon were hiding out.
52:26He had to try a new approach.
52:29The water levels in the creek are low and dropping
52:32and it means that the salmon that are in the system now,
52:35they're not moving.
52:36They're just sort of staying in the deeper pools.
52:39So it means that if the fish won't come to me,
52:43I'm going to have to go to the fish.
52:47Since he didn't have a shaggy fur coat,
52:49Geoff squeezed into a dry suit to protect himself against the icy water.
52:56The camera needed to be on the bottom of the pool,
52:59some ten feet deep.
53:01But getting down there in an air-filled dry suit was no easy matter.
53:14I'm bobbing!
53:16Geoff clearly needed to put on some weight.
53:22I feel like I'm in some sort of old medieval movie or something.
53:25Yeah.
53:27Mel Brooks or something.
53:31Young Frankenstein.
53:33OK.
53:41With his improvised diving belt,
53:43he could now get down deep enough to position the camera.
53:52The bears were learning very quickly
53:54that Geoff and his crew were not a threat.
53:57They watched him curiously as he retreated to a respectful distance
54:02and controlled his camera from his laptop.
54:08What would the bears do next?
54:16He didn't have to wait long before the first bear waded into the pool.
54:21But this youngster seemed totally out of his depth.
54:25It's really funny, this little guy.
54:27He doesn't know how to get down there,
54:29so he can't quite reach the bottom.
54:32So he's just hanging and bobbing along here.
54:43Oh, he's got his paw on it!
54:46Dammit, he knocked it over.
54:50I think he used it to stand on.
54:52Kick himself off.
54:56The fish are going straight downhill.
55:00It's a really steep river.
55:03It was back into the chilly water for Geoff to realign his camera.
55:18Soon it was up and running again and getting some intimate shots.
55:23He's got a good shot of his privates there.
55:30Although the salmon were still just out of reach of this persistent young bear,
55:34the camera wasn't.
55:36Oh no, he's getting close to the camera.
55:40Be careful there.
55:41Oh, shoot.
55:45He totally knocked it over.
55:47I'm going to have to go reposition the camera.
55:49The youngster continued to cause problems.
55:52He kept on knocking over the camera.
56:01Then two bigger, more experienced bears appeared on the scene,
56:05right in front of Geoff.
56:14But the remote camera was having trouble keeping up.
56:17The remote camera was having trouble keeping up with the action.
56:25To discover exactly what was going on, Geoff needed a new perspective.
56:30These bears were so unfazed by his presence
56:33that he decided to stay in the water
56:35and hand-hold the camera on the end of a long pole.
56:47The bears were learning to trust Geoff, allowing him to get even closer.
56:56To get as intimate as this with wild grizzlies
56:59is potentially extremely dangerous
57:01and required all of Geoff's many years of experience.
57:05That was good.
57:08OK, we've got this other guy coming out too now.
57:17He's going to check it out.
57:19OK, you can have a look at it.
57:21He was now close enough to observe their technique in detail.
57:24This was something that Geoff had never seen before.
57:27By kicking the salmon into the shallows,
57:30the more experienced bears were able to grab themselves an easy meal.
57:34And by hand-holding the camera, Geoff could follow the action.
57:44OK, we're getting close here.
57:48He's coming up to you right now. Roll.
57:52To get as close as this to an adult grizzly bear is truly remarkable.
57:57Geoff makes it look easy,
57:59but it takes years of experience and understanding.
58:07OK, good show, guys. Thank you.
58:09That's it. We're done.
58:12Yeah, it's time to go. That's it.
58:15Geoff had managed to enter the bear's world,
58:19giving him the most intimate shots
58:21of grizzlies fishing underwater ever filmed.
58:24He had achieved this not just by using new technology,
58:28but through his own special understanding of these incredible animals.
59:14.