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For many people, the opportunity to encounter a whale in the wild is a lifelong aspiration. The thrill of seeing these majestic marine mammals enjoying the freedom of their natural habitat often goes beyond being just a memorable event to a truly life-changing experience. One of the most interesting cetacean behaviours is unique to the Humpback Whale. While scientists and researchers already knew about the co-operative method they employ – called "bubble net feeding" – it was captured with brilliant, high definition success on the much-lauded BBC documentary series Blue Planet II, with Sir David Attenborough. Humpbacks and Bubble Net Feeding In Northern Norway, deep into the Arctic Circle, one of the planet's most spectacular feeding frenzies takes place in the icy ocean around Tromsø. The presence of an estimated one billion spawning herring attracts the Humpbacks to gather close to shore and gorge themselves on a veritable smorgasbord of fish. While Killer Whales have traditionally followed the herring to Norway for their winter feast, it's only in recent years they've been joined by Humpbacks. Due to the increased number (which also includes, more latterly, the endangered Fin Whales), the level of activity has risen to spectacular proportions, and it's an astounding sight. Co-operative Feeding What's different about the species, however, is the Humpbacks' unique co-operative method of catching fish and krill. A single whale (or sometimes several from a group) slowly circles the perimeter of the herring ball (a tightly packed school). They corral the fish in an ever-decreasing circle by creating a "net" of bubbles as they exhale through their blowholes. The mass of bubbles forces the fish upwards through the water and when they're at the surface the whales surge upwards, mouths wide open, capturing hundreds at a time and swallowing them whole. There is suggestion that within the circle it is silent, but the vocalisations as the whales communicate with each other during the round-up creates a sound of such intensity that it's impossible for the fish to pass through and escape. Why Do They Do It? The behaviour is one of the very few instances of surface feeding that Humpbacks display. Another method, known as lunge feeding, is similar but it is only undertaken on a solitary basis. There is speculation that this kind of co-operative behaviour is a method of socialisation for the whales, while others posit that environmental factors are at play. The most commonly held theory, however, is that they have developed the feeding strategy simply as a matter of survival – as it is highly efficient at feeding large numbers very quickly. What we do know is that bubble net feeding is a learned behaviour and only certain populations practice it. Encounter the Giants of the Ocean on Whale Watching Cruises Professionally-organised whale watching cruises to various oceans around the world offer the chance for nature lovers to get a genuine insight into the life of these giants of the ocean and observe first-hand some of their complex behaviours. For anyone fortunate enough to be embarking on one of the range of whale watching cruises, doing some pre-trip reading (and watching documentaries such as Blue Planet II) to learn how and why certain species live, breed and hunt will provide an excellent grounding. Author Plate Marissa Ellis-Snow is a freelance nature writer with a special interest in whale watching. As a passionate lover of marine wildlife, Marissa chooses the expert-led whale watching cruises organised by Naturetrek, which have brought her unforgettable sightings of a wide range of wildlife in some of the most spectacular regions on Earth.
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