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