Abstract
Commercial individuals of Corbicula japonica were mainly collected in downstream areas of the Ibi/Nagara Estuary and in upstream areas of the Kiso Estuary. Abundance of these commercial individuals increased from spring to early summer and then decreased from autumn to winter for both estuaries. Based on cohort analysis using shell length data, annual catch yields of the clam were sustained by new recruits every year: increase of the abundance of commercial individuals by new recruits from spring to early summer, and then decrease of the abundance due to the decline of new recruits by fishing mortality from autumn to winter.
