Atsushi Yamasaki, Shigeru Ohki and Eiji Tanaka

　

Nippon Suisan Gakkaishi, 67(2) : 244-251 (2001)
　

In order to estimate the mortality coefficients of adult female snow crab　Chionoecetes opilio　in the waters off Kyoto Prefecture, tagged ones were released in fishing ground in the closed season in 1990 (group I), 1995 (group II), 1996 (group III) and 1997 (group IV)．Further, in the water of 270 m depth inside the preserved area (13.7 km２), tagged females were released in 1995 (group V)．Using maximum likelihood approach with the recoveries every 1-fishing year term after release in the each group, total mortality coefficients (Zi ) for groups I and II〜IV were estimated to be 1.699 and 0.975〜1.181 year−１, respectively．On the other hand, Zi for the group V was estimated to be 0.561 year−１．The difference of Zi is discussed． Recent decrease in amount of discard by Danish seine fishery was considered to cause it because a part of the fishing ground where the fishery exploited the crab as bycatch had been seasonally closed．