Characteristics of catch and stock in walleye pollock, Theragra chalcogramma, off Iwate prefecture [Japan], Pacific coast of nothern Honshu, during April-June 2004
2005
Goto, T.(Iwate-ken. Fisheries Technology Center, Kamaishi (Japan))
A large number of walleye pollock, Theragra chalcogramma, were caught unusually by bottom trawl fisheries from off Iwate Prefecture during April-June 2004. Catch by bottom trawl fisheries and the frequency distribution of size were estimated on the basis of the landing data at all fish markets of Iwate Prefecture and the body length frequency at Miyako Fish Market, and the stock size was estimated from the bottom trawl survey by R/V Iwate-maru. Age composition, GSI and stomach contents were estimated on the basis of the samples landed at Miyako Fish Market and collected by the bottom trawl survey. Catch by bottom trawl fisheries from April to June amounted to 12,173 tons including 95 % of 4 years old fish. From the bottom trawl survey, the stock size in May was estimated as 56 million individuals and 16,267 tons in which an age class of 4 years bld was dominated. The dominant age class born in 2000 was suggested as a stock migrated temporarily from the spawning area off Funka Bay Hokkaido, because of the southern extension of the Coastal Oyashio to off Iwate Prefecture in April 2004.
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