Seasonal changes of fish fauna along the Pacific coast of Aomori prefecture, Japan
1997
Kawabata, A. (Tohoku National Fisheries Research Inst., Shiogama, Miyagi (Japan))
The inshore area along the Pacific coast of Aomori prefecture is an important fishing ground for gill net, boat seine, purse seine, etc. and is an important nursery ground for many species. Seasonal changes of the near-shore fish fauna in this area water studied by monthly sampling using a small trawl (width 55m, height 3.6m, cod end 2 mm mesh) from December 1991 to December 1992. Larvae, juveniles, young or adults of 67 taxa (include 17 cold water species and 19 warm water species) in 38 families were taken during this survey. The monthly number of taxa sampled were abundant during the low water temperature period from March to May, but the monthly sum of individual numbers per an hour trawling were abundant in the comparatively high water temperature period from August to November. Monthly species composition particularly changed between May and June or August and September, and these were classified according to the similarity between them into 3 terms as from January to May, from June to August and from September to January. The general logarithms of the number of individuals of each taxa and month were regarded as a 67 x 13 data matrix available for factor analysis. The factor analysis showed that the seasonal variability of each taxa was caused by 3 principal factors. These 3 factors were interpreted as the effects of the Oyashio current, Tsugaru warm current and high water temperatures. Common taxa were classified into 4 groups according to relation between each taxa and these factors. The taxa abundant during strong influence periods of the Oyashio current (factor 1) were mostly resident species, while those abundant during high temperature periods (factor 3) were mostly migratory species
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