Permalink : http://hdl.handle.net/2115/44758

KEYWORDS : west coast of Hokkaido;scallop;seedling production;ADCP;CTD;backtrack calculation

Shelf area off the west coast of Hokkaido(Ishikari bay,Rumoi shelf and Teshio shelf)is one of the major seedling productions of scallop. However,since there have been no surveys of wild scallop,natural spawning ground maintaining the seedling production has not been resolved still now. To improve our understanding of immature scallop,a large number of larvae collected in the seedling production area were numerically backtracked to take into account the advection,which was roughly inferred from the analysis for mooring current,ADCP,GEK and hydrographic data. Northward flow mainly affected by the Tsushima Warm Current and estuarine flow from Ishikari River is characterized by intense shelf-edge flow and weak flow with a large periodical variation on the shelf. The model result suggested,at least,two major spawning grounds. One is somewhere about southern area outside of the shelf(south of Syakotan peninsula),and another is the southern end of Rumoi shelf where there may be spawning from scallop of the aquaculture.