長崎南西方大陸斜面域の底生魚類群集

概要

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In the period from May 2006 to December 2008, a series of beam trawl surveys was carried out during the daytime to obtain the quantitative and qualitative information of demersal fishes from the continental shelf margin to the upper continental slope, southwest of Nagasaki Prefecture between depths of 155m and 608m. A total of 2713 individuals of 4 subspecies and 127 species belonging to 60 families were collected from 60 hauls performed. The dominant fish species in terms of abundance were squalid sharks (Etmopterus brachyurus), congrid fishes (Acromycter nezumi, Congriscus megastomus), neoscopelid fishes (Neoscopelus macrolepidotus, Neoscopelus microchir)and macrourid fishes (Caelorinchus anatirostris, Coryphaenoides marginatus, Ventrifossa farmani). Four bathymetric faunal zones of demersal fishes collected with a beam trawl could be recognized based on both group－averaged clustering and non－metric multidimensional scaling, i.e. 1) the continental shelf margin zone (shallower than ca. 200 m), 2) the upper slope zone of the upper continental slope (ca. 300 m), 3) the middle slope zone of the upper continental slope (ca. 400 m－500 m), 4) the lower slope zone of the upper continental slope (deeper than ca. 600 m).