IB03-3 ORAL

SPECIFIC FEATURES OF DISPOSITION OF BENTHIC ICHTHYOCENES WITHIN THE PACIFIC WATERS ALONG THE NORTHERN KURIL ISLANDS AND SOUTHEASTERN KAMCHATKA IN RELATION TO OCEANOLOGIC FACTORS

A.M. ORLOV (Russian Federal Research Institute of Fisheries & Oceanography (Vniro), Vniro, 17, V. Krasnosel'skaya, Moscow, 107140, Russia, orlov@vniro.ru)

The study of spatial structure patterns of benthic fish communities has not only scientific but also practical interest. One of the methods of such study is mapping on the basis of bottom trawl surveys that is accompanied with determination of areas with similar species composition and definition of dominating species.On the basis of data obtained from about 2,000 bottom trawl hauls conducted aboard Japanese trawlers in the Pacific waters off the northern Kurils and southeastern Kamchatka during 1993-2000 the mapping of benthic fish communities was made. The study area was divided to sections with latitudinal and longitudinal sides that were ten minutes. Within every section the average species composition, shares of all the species according to abundance, dominating species were calculated and similarity among sections was determined. This information was used for mapping of the area considered.According to dominating species 19 types of benthic ichthyocenes were distinguished. The most abundant (with frequency of occurrence over 2 %) were only 7 types of ichthyocenes with domination of darkfin sculpin Malacocottus zonurus (7.8 %), Pacific ocean perch Sebastes alutus (5.4), rock sole Lepidopsetta bilineata (33.7), snailfish Elassodiscus tremabundus (16.3), Atka mackerel Pleurogrammus monopterygius (10.8), broadbanded thornyhead Sebastolobus macrochir (2.4), and popeye grenadier Coryphaenoides cinereus (10.8), that occupied totally 87.2 % of the area studied. Very various oceanologic and ecologic conditions (bottom temperature, currents, relief, vertical zonality, distribution of forage organisms, etc.) of the Pacific waters along the northern Kurils and southeastern Kamchatka cause the extreme diversity of benthic ichthyocenes here.