Intermediate culture of asari clam Ruditapes philippinarum in Usu Bay, Hokkaido

Intermediate culture of artificial seeds of asari clam, Ruditapes philippinarum, was conducted in bags formed of raschel net with gravel mixed with fragmented scallop shells or pelletized oyster shells as a substrate in the fishing ground of the asari clam in Usu Bay, the east coast of Funka Bay, Hokkaido (Japan). Small (mean shell length, 1.11 mm) and large seeds (10 to 20 mm) were cultured in the bags placed on the sea bottom for 10 months from June 2, 2014. The growth rates of the artificial spats were comparable to those of natural clams in Hakodate Bay. The grain size of the sediments of Usu Bay was considered to be too fine for the Asari clam culture. However, use of the intermediate culture system tested in this study may help improve Asari clam production in Usu Bay.