Discarding of the Japanese mantis shrimp Oratosquilla oratoria by small-scale trawlers in Tokyo bay [Japan].

摘要: In Tokyo Bay small-scale trawlers discard considerable percentages of their catch the Japanese mantis shrimp Oratosquilla oratoria, but no quantitative survey has so far been carried out. We aimed at making clear actual fishing mortality, performed a monthly on from April 1989 to 1990 discover seasonal changes, and estimated mortality rate after discarding through simultaneous board experiments. The results revealed that both percentage discarded individuals are highest in summer, which was considered be caused mainly by high air temperature. total, 2.4 times as large those landed were died year.