Changes in inferred spawning areas of Todarodes pacificus (Cephalopoda : Ommastrephidae) due to changing environmental conditions

Annual catches of Todarodes pacificus in Japan have gradually increased sin ce the late 1980s. Paralarval abundances have also been higher since the la te 1980s compared ro the late 1970s and mid-1980s. Here is proposed a possi ble scenario for the recent stock increase based on changing environmental conditions. Based on trends in annual variations in stock and in larval abu ndances, catches are reviewed and potential spawning areas inferred, assumi ng that egg masses and hatchlings occur over the continental shelf at tempe ratures between 15 and 23 degrees C. Changes are then inferred in the spawn ing areas during 1984-1995, based on GIS data. Since the late 1980s, the au tumn and winter spawning areas in the Tsushima Strait and near the Goto Isl ands appear to have overlapped, and winter spawning sites seem to have expa nded over the continental shelf and slope in the East China Sea. (C) 2000 I nternational Council for the Exploration of the Sea.