The authors started field observation mainly around the Musashi Bank in 2009, in connection with a planning of fishing ground development in the exclusive economic zone around Hokkaido. It considered the migration pathway of the larva of alaska pollack that was the target of the resource conservation. Bloom and snowmelt flood occurred in the juvenile stage, the primary production increased at each event, and the diet environment on the pathway was improved. Temporary lack of the nutrient salt on the surface was canceled by the vertical circulation at nighttime, the primary production rate was calculated about 1278 (mg-C/m2/day) in March. It decreased markedly under the assumption of the stratification in summer. It was suggested that bloom and snowmelt flood in this area are suitable for its life history strategy.
