北西太平洋におけるサンマの分布と近年の資源動向

摘要

Pacific saury Cololabis saira (Brevoort) is a widely distributed pelagic species in the north Pacific. In recent years, the mid-water trawl surveys have been conducted in the western half of the north Pacific in June and July. The Pacific saury mainly distributed between 155°E and 165°W from 2003 to 2009. In 2010, the distribution shifted to the offshore waters further than 167°E. The stock sizes by trawl survey were stable from 2004 to 2008, but decreased in 2009 and 2010. The catches and abundance index about fishery increased during the 1950s, decreased late 1960s, fluctuated largely from early 1970s to mid-1980s, increased rapidly from late 1980 to mid-1990s, sharply decreased in 1998 and 1999 and increased in 2000s. Significant negative correlation between the abundance index and SOI suggested that ElNino events have impacts on the large size group saury. The decadal-scale variation pattern in Pacific saury is associated with oceanic regime shifts in the Kuroshio region. The abrupt change in the abun-dance of saury which occur in1987/88 appears to be a consequence of the oceanic regime shift in the Kuroshio region.