北上期における三陸海域でのマイワシ群の回遊に果たす暖水ストリーマの役割

概要

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The authors have shown in their previous report that the fishing ground of the Japanese sardine Sardinops melanostictus during their northward migration off the Sanriku coast is formed by schools coming from offshore waters, where warm streamers (WS) possibly serve as migration routes. This report suggests that the existence of WS has a close relationship with the migration and formation of fishing grounds of the sardine. The movement of WS and fishing conditions were analyzed, using Satellite imagies, satellite-aided SST distribution charts, data on fishing grounds etc. in the period from 1987 to 1990. As a result, the following were found: (1) The formation of fishing grounds and the increase in catches are caused by the approach of WS. (2) When a minute WS branches from a WS, sardine schools move across the Oyashio cold water and transfer into the coastal water. (3) Two cases are possible in the crossing of sardine schools over the Oyashio cold water during northward migration, i.e., directly by the WS, or by WSs progressively generated on a medium scale, a small scale, and a minute scale. Thus, the WS is regarded as a “migration route” for the migration of the sardine.
公益社団法人日本水産学会の論文