The Hokkaido fishery is formed by the convergence of the Japanese Warm Current (called the "Kuroshio" in Japan) and the Chishima Cold Current (called the "Kichijo" in Japan).

Seas rich in marine fisheries are often where warm and cold currents meet. Two different temperature currents meet, the temperature of the sea water is very different, will inevitably cause the surface of the sea water and deep sea water continuous vertical movement, so that the seabed nutrients come up to nourish the plankton, and thus attract a large number of fish to swim. Several large fishing grounds in the world have such natural conditions.