1Hokkaido Kushiro Fisheries Experimental Station, Kushiro, Hokkaido 085-0024, 2Hokkaido Abashiri Fisheries Experimental Station, Abashiri, Hokkaido 099-3119, 3Hokkaido Central Fisheries Experimental Station, Yoichi, Hokkaido 046-8555, Japan
In 1989, a dominant year class of Sakhalin surf clam Pseudocardium sachalinense occurred off Noboribetsu, Hokkaido. During the survey, the high-density main habitat of the dominant year class was distributed about 4km along the shoreline and remained unchanged. However, the depth range of the habitat had narrowed to 7-13m depth in 1994 from 3-13m depth in 1990. It was estimated that the capacity for clam biomass was limited to 15-16kg/m2 in the sea area. It was considered that shell growth and fresh yield of Sakhalin surf clam at 4 years old were restrained when the inhabiting density excuded 2-3kg/m2.