小型定置網への魚群の入網時刻

抄録

In order to identify the entrapping time of fish into the set-net, experimental operations were conducted at a small scale set-net fishing area in Tateyama Bay, Chiba prefecture. The bag net was hauled up 6 times per day at 03:00, 07:00, 11:00, 15:00, 19:00 and 23:00 hours at 4 hour intervals. A total of 60 hauls at 6 different times of day were made and the catch was recorded for each species for studying the entrapping time of fish. Total catch was increased at the twilight time and the catch patterns of the main species were classified as the diurnal, nocturnal, crepuscular and aperiodic types. For example, the diurnal type included frigate mackerel Auxis thazard, the nocturnal type bottom perch Apogon semilineatus and flying fish Prognichthys agoo, and the crepuscular type round herring Etruneus teres and jack mackerel Trachurus japonicus.