A Long-Term Simulation Study on Variability of Short-Necked Clam Resources in Ise Bay in the 1990s

Abstract

To investigate major causes of the variability of the short-necked clam (Ruditapes philippinarum) resources in Ise Bay in the 1990s, we carried out a long-term numerical simulation using the 3D hydrodynamic and biogeochemical cycle model coupled with the life cycle model of the short-necked clam. The calculated results of the clam yields agreed with the observed variability; the decrease trend during 1990-1996 and the increase trend during 1997-2000. The results indicated that the clam yields mainly depended on the pelagic-larval settlement. The key factor of the pelagic-larval settlement was the change in the spawning rate depending on the sea temperature in the spring spawning seasons. The sea temperature in the spring spawning season was considered to be the major cause of the clam yield variability during 1990-2000 in Ise Bay.