1990年代後半以降の我が国日本海沿岸域におけるスルメイカ漁獲量の減少について

抄録

The stock status of Japanese common squid Todarodes pacificus has been at a favorable level, but landings in coastal areas of the Sea of Japan have decreased. In the present study, this decrease was examined using monthly landing statistics from Japanese fisheries fiscal years 1994–2008. Landing statistics were examined in four regions: Northern Hokkaido, Southern Hokkaido, Northern Honshu and the Western Sea of Japan. Significant decreasing trends (p<0.01) in the monthly landings were observed during September and October in Northern Hokkaido, July and October in Southern Hokkaido, August and November in Northern Honshu, and May and November in the western Sea of Japan. No increasing trend was observed in any region. Annual rates of decreasing during August and December in Northern Honshu, and during August and September in the western Sea of Japan were approximately 15–25%. These rates correspond to approximately 95–99% over 15 years, which means the fishing grounds disappeared in these regions. Decreasing trends were observed more commonly in southern areas and during summer and autumn. These results suggest that the decreased landings during 1994–2008 might have been linked to the warming of the Tsushima Warm Current that occurred from the late 1990s.