"With the help of a little modern technology..." "I've been listening to the calls... of one of the great predators of the ocean... feeding maybe two or three miles from here." "Surprising though it may seem... those are the sounds of the humpback whale." "Close to, the noise is staggering." "Hunting herring is far from easy... but the small fish have a major weakness." "They use tiny sounds to control the movements of their shoal... so their sense of hearing is acute." "And at 180 decibels, the humpback screams are completely overpowering." "This is predation on a massive scale." "Very few of the herring are lucky enough... to fall back into the sea unharmed." "That humpbacks scream as they hunt has only been discovered recently." "Indeed, research is now revealing that the whales... far from being the gentle giants of popular belief... have a very aggressive side to their characters." "South East Alaska in mid December." "Several hundred humpbacks have spent the entire summer here... cruising between the islands of the Inside Passage... feeding on the rich plankton and fish stocks." "Now the chill of approaching winter heralds a change." "Thousands of old squaw duck have migrated here from the polar north." "Compared to the arctic these conditions are comparatively mild... and the ducks will spend the winter feeding in these sheltered waterways." "But for most of the humpbacks... there is a pressing need to set off on an epic journey of their own... even though they are at no risk from the cold." "By the end of December the whales are heading south." "Blowing for breath regularly... and travelling singly or in small groups... the humpbacks keep up a steady pace of about six miles an hour." "The sound of their passage attracts a pod of pacific white-sided dolphins." "Eventually the whales must set out into the open ocean... for a voyage of three and a half thousand miles." "The islands of Hawaii in January." "The volcanic sea cliffs here are the tallest in the world... and in the vast Pacific Ocean, they provide rare protection... from the wind and swell." "So, this subtropical water is an ideal sheltered nursery... in which humpbacks can raise their young." "This was the reason for the great migration, to breed." "Hawaii is visited by about 5000 humpbacks every winter." "Several hundred of them are mothers with their calves." "The maternal bond is exceptionally close." "This fifty tonne cow and her four week old calf... will be inseparable for about ten months." "As he's still quite a weak swimmer... she gives him an energy-saving piggyback ride... and gently nudges him up to the surface to help him breathe." "But they are not alone." "Another large adult cruises in to join them." "At first, some scientists thought visitors like this were females..." ""aunts" helping out with the calves." "In fact they are males... and probably the last thing on this escort's mind... is the calf's well being." "This trio of cow, calf and male escort... is a common social group in the breeding area... but the liaison is tense because, soon after giving birth... the cow is ready to mate again." "The escort is almost certainly waiting for his chance." "But the cow has other more pressing engagements... her calf needs to suckle regularly... and nudges in under her huge four metre pectoral fins." "For now, the male seems patient enough to wait." "The lungs of baby whales are only small... so his mother has to release him regularly... from the protective clasp of her fin." "The adults can remain underwater for up to forty minutes." "For the calf it's a different story." "Every four or five minutes he has to surface all by himself... and gulp for air." "Twenty metres below, the adults wait for the calf's return to the nipple." "Schooling mackerel also head for the immense bodies... perhaps using them as a temporary shelter... in the vast expanse of the open ocean." "The small group may remain together for days at a time... gently moving about between the islands." "Idyllic as their setting may seem... it's vital that the calf develops in size and strength quickly... his survival may depend upon it." "One month has passed." "The calf is doing well... hugged protectively by his ever vigilant mother." "As before, as soon as he needs to breathe she releases him." "But trips to the surface are no longer so daunting or frequent." "The calf has grown both in size and independence." "A breathing expedition now is a perfect excuse for some fun." "The play is excellent for improving much needed stamina... but the commotion may also attract the attention of other whales... and people." "Like scientist, Jim Darling." "He's been working with humpbacks for 18 years... slowly trying to discover more about their behaviour... because if we are to conserve these great whales properly... we must know what their needs really are." "Humpbacks are world famous for the beauty of their singing... but Jim's main interest is in its social function... so he uses a hydrophone to locate and listen to singers." "Only males sing... so it's almost certainly a sexual display of some kind... and the Hawaiian singers often lie motionless... with their pectoral fins thrust down and held stiffly outwards." "All the whales sing roughly the same song... a rigidly structured pattern of themes lasting about 12 minutes... which can be repeated almost without break for hours on end." "A passing whale eventually moves in to check out the singer." "Is this a female attracted by the bull's voice... or another male assessing the strength of the competition?" "In any event the singer is disturbed and quickly moves on." "Sometimes the intruding whale will catch up with the singer... and swim with it for a few minutes." "But is this passion or war?" "Jim's task is to identify and sex the incoming whales... to try and solve the riddle." "First he takes photos of the tale flukes... and then waits to snap the dorsal fin as well... both are uniquely marked or shaped... and will identify the animal for future reference." "I think it is the one with the white tail." "But sexing a whale is another matter altogether." "The best technique is to take a skin sample." "But it's a very difficult thing to do." "Just manoeuvring a boat close to a whale without disturbing it... takes great skill." "So research assistant Karen reacts instantly to every direction." "A little more this way." "And they need to get close enough to fire a low powered dart... that collects a tiny plug of skin." "Done correctly, it causes no alarm." "The sample will be sent back to the laboratory for DNA analysis." "It will reveal the whale's sex and genetic details... and Jim's preliminary results have shown... that all the joining whales he's tested are male." "So it seems that the song could indeed be... an elaborate communication of male status." "Perhaps it's war after all." "And when it comes to competing for a mate... the bulls do more than just sing." "There are over one thousand of them around Hawaii... so the competition for females is intense." "Even cows with calves are fair game... and the females may actually encourage the bulls' attention." "For the calf this will be a testing time." "This bull, with distinctive white pectoral fins, is the escort... and he moves in quickly to claim his right." "But the cow still heads off with her calf close beside her." "And a male soon picks up the chase." "The escorted group changes course... perhaps the bull is trying to shake off the pursuers." "But following them is easy." "The escort tries a threat display by blowing jets of bubbles underwater." "Perhaps it helps establish a dominance pecking order... in the queue following the cow." "Another bull moves closer." "Blowing like a surfacing submarine, the escort moves in to intercept." "The female lifts her head clear of the water." "After swimming at ten miles an hour for some minutes... the calf is tiring and flails in distress." "The bulls are overhauling them." "As yet another male powers up from behind, the cow finally stops... slapping her flipper loudly." "With bulls circling her continuously she starts tail slashing... perhaps to fend off the less desirable mates." "And in another attempted display of dominance... the escort moves towards her with his fins held stiffly outstretched." "Undeterred, up to seven males circle the cow, totally surrounding her." "They hoot as they manoeuvre for prime position." "The competition becomes yet more intense... as one of the bulls chases the escort away." "Now the cow is an unprotected target." "During the ensuing confusion... it's possible that she will be finally mated." "Thrashing weakly, the calf by now is close to exhaustion." "So his mother glides up to reassure him... and if necessary, give physical support." "But for the moment they are ignored." "The bulls are too engrossed in a conflict... where collisions may even draw blood." "By now, the cow has probably mated successfully... so she takes the chance to slip away... and not before time, her calf desperately needs to suckle." "If these chases happen too often... it's possible that the stress and lack of feeding... could be fatal to calves." "By February, Jim's team is joined... by the renowned underwater stills photographer, Flip Nicklin." "The two have worked together, on and off, for over 18 years... and they're quickly amongst the whales." "Suddenly they notice something strange about one of them... it dives with a lopsided tail." "It's a style that's reminiscent of a whale... that was a major landmark in their research... and they last saw him 18 years ago." "They approach with a real sense of growing excitement... could it be the same whale?" "This is a unique opportunity." "Eighteen years ago, Flip and his father, Chuck... became the first people to dive down to a singing whale." "Their breakthrough was to hold their breath... instead of using scuba gear with its noisy bubbles... and the photos they took were the first proof that singers are male." "Diving this close to a singing whale is an extraordinary experience... its voice is so strong... that the whole of Flip's body is physically vibrated." "He's searching for identifying marks in the whale's tail... because Frank had a big ragged tear in his left fluke... with deep lacerations from a cable entanglement." "Amazingly, after all this time..." "Flip was indeed looking at the very same tail." "It was Frank." "Unable to hold his breath any longer..." "Flip is forced to head for the surface." "Remarkable though Frank's rediscovery was... it also revealed just how little we know about these animals." "Where had he been during all this time?" "It's possible that he had visited Hawaii every year... and had simply not been seen." "But other Hawaiian humpbacks... have been spotted in breeding grounds off Japan... and islands near to Mexico's Pacific coast." "It appears that they are all part of the same population... sharing similar songs and wandering as they please." "But there are humpback song cultures in the Pacific... that Frank is unlikely ever to meet." "February, on the edge of the Antarctic ice shelf." "The northern hemisphere is still in midwinter... but down here it's high summer... and humpbacks visit annually to harvest the rich pickings." "This is an entirely different group of whales to those in Hawaii." "All too soon severe cold will drive them north... to breeding grounds of their own." "But they remain south of the equator... amongst the South Pacific islands of Fiji and Tonga." "There are only about 100 humpbacks around Tonga... because, until recently, they were hunted... and it's the first time that Flip Nicklin's father, Chuck... has visited these islands so he's far from certain of finding whales." "But after a week of waiting... he's finally spotted some activity and sets off to investigate." "He approaches as quietly as he can." "His luck holds... this is the first time he's ever seen a Tongan whale... and it's a mother and calf." "Edging closer reveals that the calf is very young... the crease on its side is from being curled up inside its mother's womb." "And remarkably it's almost pure white." "In fact, Southern whales are quite different from those of the north... and even the adults have far more white markings." "Although Chuck has been diving with whales for thirty years... swimming this close is still a huge thrill... and the cow and her calf seem totally unconcerned." "Perhaps there are so few bulls here... that there isn't as much sexual harassment as in Hawaii... so the cow is more tolerant." "But there are some males here." "The song is very different to those of the Northern Pacific... with extraordinary chirps and screams." "This singer's action is also quite different... even whilst it rolls and plays, the song keeps booming out." "It seems a much more light hearted performance... and it's easier to make an approach." "Although they can cross the tropics..." "Southern whales are governed by the seasons of the south... so they breed six months later than the Northern Pacific humpbacks... and they must also head south to feed." "This male's song will probably never be heard north of the equator... and will always sound quite different." "He is from a distinct population with its very own language." "Researching whale movements and cultures on a global scale... is incredibly difficult." "How on earth can you follow a migrant across thousands of miles?" "One man who does just that is professor Bruce Mate." "He's using hi-tech telecommunications... to track some of the Hawaiian whales on their northbound migration." "A satellite transmits positioning signals from tagged animals... revealing their precise location, day or night." "The results are already extraordinary..." "Hawaiian humpbacks don't have one single destination... they radiate out to feeding areas all over the north Pacific." "This group is nearing the coast of South East Alaska." "The rugged coastline is fringed by hundreds of mountainous islands... and the cold water that separates them... is some of the most productive in the world." "At the end of their long journey the whales seem almost exuberant." "They breach and slap their flippers repeatedly." "It's a phenomenal display it takes enormous strength... to hurl a 50 tonne body out of the water." "The strong tidal rips that run here, literally seethe with fish." "Countless millions of herring cruise near the surface... sipping individual plankton from the dense summer bloom." "But catching plankton can be a risky business." "Herring is a favourite on Alaska's coastal menu." "The shoal bunches into a protective ball." "But it's little defence against diving gillemots and auklets." "From above young herring gulls add to the feeding frenzy... and the commotion attracts a dogfish." "Before long there are extraordinary numbers of these small sharks... on the prowl for herring." "But to try and escape the shoal has dived deep." "Depth is no guarantee of safety." "A wall of bubbles rises up to the surface, expanding noisily." "The line keeps growing until it becomes a complete ring." "Corralled by the vertical net of bubbles... the herring are trapped at the surface." "It's the worse place to be!" "A lone humpback lunges into the centre of his bubble net." "The whale can repeat this attack every few minutes for hours on end." "The spread of its jaws is over four metres... and pleats in the whale's throat... stretch enormously along half its body length... allowing it to engulf hundreds of gallons of water." "A single gulp can devour an entire shoal." "Rich feeding like this attracts dozens of whales... often in large groups, and little is known... about the social structure of the groups or their movements." "Bruce Mate is keen to use his satellite techniques... to discover more about whale behaviour in feeding areas." "He believes knowing where important humpback feeding areas are... and how the whales utilise them... will help us to ensure that the right protection is given... both to their environment and the whales themselves." "But first he must tag some whales." "His team uses a manoeuvrable boat for close approaches... they must be close enough to dart the whales... with a small satellite transmitter." "Barb, the skipper, has to time her runs perfectly... to get Bruce into exactly the right position at the right time." "If at the last second... the whale surfaces in slightly the wrong place, they abort the pass." "It's an enormously skilled and tense operation." "Safety off." "Let him come up again, let him come up again, if it will." "Okay, go, go, go." "Yes!" "Yes indeed!" "Alright." "After retrieving the dart's sleeve with a thin line..." "Bruce and his crew will take photos of the tagged whales for reference." "They are still far from certain that a tag will work... a satellite has to be able to pick up its signals." "Even with a satellite in the right position... the system will only operate... if a tagged whale comes to the surface to blow... and even then if the transmitter is angled incorrectly... they won't receive a signal." "To find out if everything is working Bruce needs to get to a phone." "It's kind of exciting, a week now..." "First time." "We're connected." "We've got data!" "Come and look." "Great." "Alright." "This is neat, look at this, all this stuff." "That's amazing!" "8.43..." "This is just the last..." "That's the first one we tagged..." "on the 2nd." "Right." "Are we hearing from all five whales?" "We can't tell, it's still giving us..." "It's still strolling by..." "Look at how many messages now." "Eight messages in one orbit." "Right, and it's just the start with everything going well... we're gonna have data coming in for a long time." "Their excitement is justified... data from the tagging has shown that the whale groups are flexible... the numbers and individuals change constantly." "They've even found that the animals move around... seeking out the best food hotspots." "But if the fishing is good they'll stay in one area for weeks at a time." "And dense fish stocks attract more than just whales." "Purse seine boats... use a mechanical version of the humpbacks' bubble netting technique." "Often whales and fishermen will work in the same area... sometimes even for the same catch." "But by June the fishing boats are not allowed to land herring... they're working the summer salmon run instead." "But salmon eat herring and plankton... so the whales may still find a catch alongside the boats." "Once the fishermen have located a shoal on the echo-sounder... they run the net out with a powerful launch... eventually making a complete circle and enclosing their targeted shoal." "The base of the net is closed and the fish pulled up to the boat." "By contrast, whales use the surface as the final trap for their catch." "When the whales are close by... great care is needed to ensure that one doesn't get caught up in the net." "As soon as an area is cleaned out or the prey move on... the humpbacks, like fishermen, move on as well... cruising the island channels in search of fresh herring shoals." "When a new shoal is located it may be deep or dispersed." "Scientists have known about bubble netting for years... but they've only recently discovered the whale's ultimate weapon... for destroying the fish shoals' co-ordination... and for herding the catch:" "the scream." "The results are devastating." "Surprisingly, only one or two whales in a group set the nets or scream." "So whether this is a choreographed team effort... or the stealthy poaching of an efficient bubble netter... no one is entirely sure, but the effect is still lethal." "And they'll feed like this for five or six months solidly." "This is predation on a scale matched perhaps only by man." "Witnessing this, it is impossible to live with the image of a humpback... as just a gentle giant." "Capable of great tenderness but also fierce in-fighting... they make journeys all over the oceans... but still have distinct population and language cultures." "Above all they are phenomenal hunters." "The Humpback whale truly is a giant of the oceans."