東京湾におけるトリガイの漁獲量変動と個体群構造 Catch Yield Fluctuation and Population Structure of Fulvia mutica(Reeve)in Tokyo Bay
The present work was carried out on the catch yield fluctuation and population structure of the cockle <i>fulvia mutica</i> in Tokyo Bay. The fishing season of the cockle is from Apri1 to early August. Most of the catches are recorded in May and June. The CPUE is high in the beginning of the fishing season and shows a sharp decrease throughout the fishing season. It seems that the CPUE is a good index of the population size of <i>Fulvia mutica</i>.<br>The catches are divided into six market size categories after landing. The two smallest market size categories account for most of the catches, and their percentages in the catch increase during the fishing season. However, shell lengths of the six market size categories are between about 43 to 70mm, and the difference in categories does not mean that in year class. More than 50 to 70 percent of the total catches are from 50 to 60mm in shell length, which corresponds to just one year in age. It is considered that the population of the cockle is dominated by one year class. Simplicity of age compositions in the population was supposed to be one of the important factors causing the drastic fluctuation in the catches in Tokyo Bay.
日本水産学会誌 63(3), 353-360, 1997-05-15