Stock fluctuations of the Japanese common squid, Todarodes pacificus, related to recent climate changes

Abstract

In Todarodes pacificus, recruitment success is most likely dependent on the physical and biological environments of the spawning and nursery grounds. Annual catches of T. pacificus in Japanese and Korean waters have markedly increased since the late 1980s and the recent catch is equal to that of the 1960s. Here re-proposed is a possible scenario for the stock increase since the late-1980s based on GIS analysis of changes in the inferred spawning area during 1984-1999. This study suggests that winter-spawning areas in the East China Sea shrank when adult stocks decreased during a cool regime, and that fall and winter spawning areas extended and overlapped in the Sea of Japan and East China Sea when adult stocks increased during a warm regime. We conclude that stock fluctuations in T. pacificus occur with annual changes of winter-spawning areas related to climatic regime shifts.