Autumn distribution of epipelagic fishes and squids in the Okhotsk sea and western north Pacific ocean off the Kuril islands and southeast Hokkaido [Russian Federation and Japan]
1998
Nagasawa, K. (National Research Inst. of Far Seas Fisheries, Shimizu, Shizuoka (Japan)) | Ueno, Y. | Sakai, J. | Mori, J.
Surface-trawl surveys were conducted in the central and southern Okhotsk Sea and in the western North Pacific Ocean off the Kuril Islands and southeast Hokkaido from late August to late November in 1996. A total of 33 fish species (one lamprey, two sharks, and 30 teleosts), 13 squid species, and some other unidentified species were collected. This paper describes and discusses the distribution patterns of abundant species. Salmonids (six species of the genus Oncorhynchus) were the most abundant (27% in number and 51% in weight of total catch), followed in number by mackerel, juvenile walleye pollock, myctophids, juvenile arabesque greenling, and Japanese anchovy. Over 98% of the salmonids collected were ocean-age 0 juveniles. Pink and chum salmon juveniles predominated. Northern smoothtongue, Japanese sardine, and various gonatid squids were also abundant. In early autumn, juvenile salmonids, juvenile arabesque greenling, and migratory warm-water species were segregated according to sea surface temperature (SST) in the Okhotsk Sea: the salmonids occurred in more northern waters than did the others. With decreasing SST during mid- and late autumn, most of the warm-water species migrated southerly to the North Pacific Ocean and juvenile arabesque greenling moved to coastal waters. Juvenile salmonids moved southward but remained in the Okhotsk Sea. Vertically migrating myctophids and bathylagids were abundant in the evening. Gonatid squids were also numerous in the evening catches. We conclude that the surface water of the Okhotsk Sea in constantly utilized by the species vertically migrating from deep waters and also provides habitats for feeding and growth to various warm-water species and juvenile arabesque greenling from summer to autumn and to juvenile salmonids from summer to autumn or winter
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