Frederick Sound
After a sunny morning spent enjoying hikes and flight-seeing from the fishing village of Petersburg we headed north into the waters of Frederick Sound in search of humpback whales. The conditions were perfect with glassy calm water, overcast sky and air so clear we could see the patterns of snow and rock on mountainsides from eighty miles away. Sea birds focused our attention nearby and sharpened our observational skills as we cruised along as though in a wonderland within a crystal ball. Soon we were spotting blows and the dark backs of whales breaking the surface even though they were still miles away.
Just prior to dinner we had the luck to encounter three humpback whales engaged in a unique feeding behavior, one seen only here in Southeast Alaska. Whale researchers have coined several terms for this behavior in an attempt to describe it but, whether referred to as cooperative feeding, bubble-net feeding, aggregate feeding or echelon feeding, it is an amazing site to behold. Humpback whales are well designed to feed by gulping large amounts of water that contain prey items such as krill or small fish and using their baleen plates to separate water from food before swallowing. Individual whales can forage quite successfully and this is pretty much the norm over the humpback’s worldwide distribution. Here in Southeast Alaska however, certain humpback whales get together in groups of three to thirty and employ some very sophisticated techniques to concentrate schools of herring (one of their favorite foods) into a tight ball and then force them against the surface where they have no where to escape. Then the whales surface from below with their mouths wide open. Blowing bubbles to form a cylinder-like net and driving the herring into the bubble trap by vocalizing and flashing their long pectoral flippers from below are some of the techniques used to make it all work.
In the photo we see the head and open mouth of one of the three whales just seconds after the trio came bursting up from the depths. Notice the fringe of baleen plates hanging from the roof of the mouth. The tongue is not visible but it's easy to see the water spilling out of the mouth. On the left notice the grooves that line the throat allowing it to expand to gargantuan proportions. These ventral pleats, as they are called, extend almost to the whale's navel. Right now the whale's mouth and throat are filled with thousands of gallons of water and thousands of herring that have no escape. All the whale has to do now is close its mouth and expel the excess water through the baleen plates, which are bristly and act as a sieve. Then with one big swallow all the herring are down the hatch!
After the whale-feeding show, and our own bout of cooperative feeding in the dining room (Ummm! Fresh caught Dungeness crab!) we had the rare opportunity to talk with Andy Szavo and Fred Sharpe of the Alaska Whale Foundation. Fred has been documenting these "cooperative" whales of Southeast Alaska for over fifteen years and founded the Alaska Whale Foundation to support whale research and conservation. Andy is working on his advanced degree and looking into the question of why the calves of female cooperative feeders do not seem to participate in this behavior once they reach independence at one year of age. At least so far they have not been observed to. Whales are long-lived creatures however and perhaps in the years to come they will rejoin the bubble-netting, echelon-feeding, aggregating, cooperative feeding humpbacks of Southeast Alaska.
After a sunny morning spent enjoying hikes and flight-seeing from the fishing village of Petersburg we headed north into the waters of Frederick Sound in search of humpback whales. The conditions were perfect with glassy calm water, overcast sky and air so clear we could see the patterns of snow and rock on mountainsides from eighty miles away. Sea birds focused our attention nearby and sharpened our observational skills as we cruised along as though in a wonderland within a crystal ball. Soon we were spotting blows and the dark backs of whales breaking the surface even though they were still miles away.
Just prior to dinner we had the luck to encounter three humpback whales engaged in a unique feeding behavior, one seen only here in Southeast Alaska. Whale researchers have coined several terms for this behavior in an attempt to describe it but, whether referred to as cooperative feeding, bubble-net feeding, aggregate feeding or echelon feeding, it is an amazing site to behold. Humpback whales are well designed to feed by gulping large amounts of water that contain prey items such as krill or small fish and using their baleen plates to separate water from food before swallowing. Individual whales can forage quite successfully and this is pretty much the norm over the humpback’s worldwide distribution. Here in Southeast Alaska however, certain humpback whales get together in groups of three to thirty and employ some very sophisticated techniques to concentrate schools of herring (one of their favorite foods) into a tight ball and then force them against the surface where they have no where to escape. Then the whales surface from below with their mouths wide open. Blowing bubbles to form a cylinder-like net and driving the herring into the bubble trap by vocalizing and flashing their long pectoral flippers from below are some of the techniques used to make it all work.
In the photo we see the head and open mouth of one of the three whales just seconds after the trio came bursting up from the depths. Notice the fringe of baleen plates hanging from the roof of the mouth. The tongue is not visible but it's easy to see the water spilling out of the mouth. On the left notice the grooves that line the throat allowing it to expand to gargantuan proportions. These ventral pleats, as they are called, extend almost to the whale's navel. Right now the whale's mouth and throat are filled with thousands of gallons of water and thousands of herring that have no escape. All the whale has to do now is close its mouth and expel the excess water through the baleen plates, which are bristly and act as a sieve. Then with one big swallow all the herring are down the hatch!
After the whale-feeding show, and our own bout of cooperative feeding in the dining room (Ummm! Fresh caught Dungeness crab!) we had the rare opportunity to talk with Andy Szavo and Fred Sharpe of the Alaska Whale Foundation. Fred has been documenting these "cooperative" whales of Southeast Alaska for over fifteen years and founded the Alaska Whale Foundation to support whale research and conservation. Andy is working on his advanced degree and looking into the question of why the calves of female cooperative feeders do not seem to participate in this behavior once they reach independence at one year of age. At least so far they have not been observed to. Whales are long-lived creatures however and perhaps in the years to come they will rejoin the bubble-netting, echelon-feeding, aggregating, cooperative feeding humpbacks of Southeast Alaska.
