The Japanese kokanee, also known as the kunimasu salmon or black kokanee, is considered a subspecies of the sockeye salmon by some and occurs naturally in Lakes Akan and Chimikeppu on Hokkaido Island. The creation of a dam caused the extermination of the fish by changing the lake pH. As a result, the kokanee was believed to have gone extinct in the 1940s. In 2011 a few fish were found in an isolated lake on Mount Fuji.