What is the favourite prey ? Foraging ecology of killer whales at avacha gulf, russian far east
|
| WHAT IS THE FAVOURITE PREY ? FORAGING ECOLOGY OF KILLER WHALES AT AVACHA GULF, RUSSIAN FAR EAST. Tarasyan K., Jikiya E. Russia, 119899, Moscow,Moscow State University,Biology Faculty, Department of Zoology Vertebrate, karen@ntl.ru Kamchatka killer whale population is studied since 1999 up to a present year by the scientific expedition organized by Kamchatka Institute of Ecology and Nature Management and Moscow State University. Methods of our research are traditional for investigations of cetacean: we use photo-identification technique, acoustic analyzing and land-based behavioral observations simultaneously. This report represents some aspects of foraging ecology of killer whales at Avacha Gulf, Russian Far East, based on two-year behavioral data. It is known that killer whales use different methods for different fish prey. We has distinguished two hunting methods: long diving of single killer whale, which is not coordinated with other group members, used for catching single fish, and “karusel” method, described for killer whales and other cetacean during chasing fish schools by the group of dolphins. Perquisition of local fishermen has allowed finding out the basic species of the fishes, which inhabit at Avacha Gulf. Some of these species, such as walleye pollock, greenlings, codfish or flounder, have commercial value. Behavior and position of orcas during foraging let us to predict fish species, which are hunted by observed killer whales. Varying ratio of two types of fish chasing and changing places of foraging from season to season allows to assume, that the basic food objects, attracting killer whale to Avacha Gulf, are changing from year to year, depending basically on large number and availability of separate possible prey species. |
