Fishery biology of Loligo edulis in Moroiso Bay,Kanagawa Prefecture, Japan

摘要

The swordtip squid, Loligo edulis Hoyle, 1885 was collected from set-net fishery in Moroiso Bay, Miura Peninsular, Kanagawa Prefecture, Japan, during April 2002 and September 2003. A total of 2,127 individuals (1,146 males and 981 females) from the mantle length between 33 and 213 mm were examined. The maturation, reproductive cycles and spawning period were determined for both sexes. Age and growth were analyzed from statolith increments and hatching date was estimated by the back calculation. Statoliths of 350 males (35-187 mm mantle length) and 232 females (39-213 mm mantle length) were examined.The estimated age ranged from 79 to 298 days for male and 83 to 277 days for female. The hatching dates were estimated to be from May 2002 to April 2003. The spawning season occurred throughout the year and the main spawning period took place between June and August. Exponential growth model was used to describe the relationship of mantle length and the estimated age of hatching month group.