Biology and fishery of Thysanoteuthis rhombus in the waters around Okinawa, southwestern Japan
Kakuma, S.; Kawasaki, K. (1998). Biology and fishery of Thysanoteuthis rhombus in the waters around Okinawa, southwestern Japan, in: Okutani, T. Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. pp. 184-189
In: Okutani, T. (1998). Contributed papers to International Symposium on Large Pelagic Squids, July 18-19, 1996, for JAMARC's 25th anniversary of its foundation. Japan Marine Fishery Resources Research Center: Tokyo. 269 pp., more
|
| Abstract |
Using research boats, test fishings in the coastal and offshore waters, at depths of 460 -5000 m, were carried out in daytime. Fishing boats were monitored to get information on the distribution and the catch per unit of effort (CPUE) through logbooks and interviewing. The mantle lengths of T.rhombus at Itoman market (southern tip of Okinawa) were measured. Gonads from the test fishing catch and commercial landings were investigated for monitoring spawning conditions. T.rhombus were caught in the areas where the ocean depth is 565- 7000 m. The fishing depth between 300 and 750 m, especialIy 450 -650 m, was considered the main distribution stratum with the highest CPUE. In the monitoring, the drop-line boat went fishing to 20 to 60 miles offshore, while long-line boats fished further 60 to 280 miles, mainly 120 to 150 miles. T.rhombus, at mantle lengths of 30 to 40 cm, recruited in the fishery in June. They attained 75 cm in March. GSI was highest in March to May (over 65 cm ML). It was considered that squids > 70 cm ML could spawn. |
|
