Stock Assessment by Larval Surveys of the Winter Population of Todarodes pacificus Steenstrup (Cephalopoda: Ommastrephidae), with a Review of Early Works
2013; Taylor & Francis; Linguagem: Inglês
ISSN
2334-1734
AutoresTakashi Okutani, Taisuke Watanabe,
Tópico(s)Neuroendocrine regulation and behavior
ResumoAbstractThis is a study of larval abundance and distributional pattern of the winter population of the Japanese common squid, Todarodes pacificus Steenstrup, based on plankton net collections made by the R/V Soyo-Maru during January to March (1959–1976) in the seas extending from the south of Kyushu to the Pacific coast of central and eastern Honshu. The larval abundance index (LI) was compared with CPUE (catch per boat day), an index of recruitment of adult stock size.The main spawning ground of this population is located to the southwest of Kyushu. The larvae (rhynchoteuthion) grow while they are advected by the Kuroshio Current to the northeast. Hence early larvae are more abundant in the west, while advanced larvae are more abundant in the east. Mortality seems to be highest for stages up to several millimeters DML than for later stages.The stock size of the Pacific winter population has fluctuated greatly. It declined since the peak 1960 year class to very low levels. The decrease of the stock size t...
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