Abstract
Standing crop of second-year sporophytes of the Rishiri-Konbu kelp Saccharina japonica var. ochotensis was monitored by a diving survey in the coast of Tsugaru, Rebun Island, northern Hokkaido Japan, Sea of Japan from 1983 to 2018. Relationship between published data of the coastal surface water temperature of northern Hokkaido and the standing crop was analyzed. A significant correlation of the standing crop and mean water temperature of April, May, and June of one year prior of the survey was found. There is a significant correlation between the standing crop and published data of the catch volume of S. j. var. ochotensis in Rebun Island, and also in the Soya Region of northern Hokkaido. Monthly mean water temperature of May and June has been increasing from 1983 to 2018. This suggests that lower water temperature in spring and early summer leads to higher kelp resources in next year.
https://ror.org/026j3ca82 
