Results (
Thai) 1:
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Class 5 could be a fishing area for both autumn andwinter spawning groups. Abundance of T. pacificus isdetermined by recruitment during the autumn andwinter spawning periods (Hatanaka et al. 1985;Murata 1989). Fishing areas that developed only inautumn were identified in Classes 1, 3 and 7, beingrecorded from the central to northern areas of the Seaof Japan. In winter, fishing areas formed in moresoutherly areas, such as the southern areas of the YamatoRise and coastal areas of Hokkaido. Bearing inmind the spawning season and migration patterns ofT. pacificus during autumn and winter, it is reasonableto consider T. pacificus in these classes as mixedspawningrecruits.Fish migrations can be linked to periodic occurrencesand to events such as spawning and feedingmigrations (Laevastu & Larkins 1981). Although thecontrol of Todarodes pacificus migration is not wellunderstood, its northward migration to the northernSea of Japan and its southward autumn-winter migrationare thought to be for feeding and to search for suitablespawning grounds (Hanlon & Messenger 1996).Currents play a dominant role in determining the patternof migration (Healey 2000). There is a possibilitythat T. pacificus would have to utilize such flows tomigrate northward, in order to save energy for foragingin the northern Sea of Japan. Thus, the oceanographicfeatures of the TWC probably influence thespatial-temporal distribution of T. pacificus. Class 4,identified in May, June, and December along the
Japanese coast from the Oki Islands to northern waters
off Honshu, coincides with the evolution of warm
eddies influenced by interactions with the coastal current
along the Japanese coast (Isoda 1996). These
areas also correspond to the location of the TWC. Class
6 developed from October to December (Fig. 10) and
showed the largest distribution of all classes. However,
Class 6 corresponded to relatively deep-water areas
with depths greater than 500 m. Class 6 may be an
area through which squid merely pass on their way to
the spawning grounds in the Tsushima Strait or along
the eastern coast of Korea (which
correspond to Class 5). It
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