| Summary: | "Eastern region of Japan where the Kuroshio and Oyashio are passing through is the most important area as a nursery ground for pelagic fish larvae such as sardine and anchovy. Recruitment of sardine stock had a high level in 1980s, but remarkably decreased in 1988-91 when the Oyashio front moved to the north. Shortly after this event, this stock collapsed. However, recruitment of anchovy and saury has quite good condition at that time and these stocks have kept a high level. Main purpose of this research cruise is to clarify this recruitment process of the small pelagic fish. In order to clarify this purpose, current field structure related to biological transport, distribution and size-species composition of plankton and nutrient concentration of sea water were analyzed using ADCP, CTD/RMS, NORPAC nets, satellite imagery, drifting buoys and EPCS in detail. In addition, larvae and adults of small pelagic fish such as sardine were collected using ORI net, IKPT, mid-trawl net and gill net to survey their concentration, growth and maturity."--Pref.
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