Kokanee salmon lake acidity. 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. The Japanese kokanee varies from its sea-going sockeye relative in a few ways. The black kokanee breeds in March at a depth of 30–40 feet, while sockeye salmon breed in the fall and have a different number of gill rakers than the kokanee. In addition, the black kokanee is much darker in color than the sockeye or any other kokanee population. The fish has been introduced to different lakes around
Sockeye salmon Resources Commission in an attempt to establish the species as a forage fish for other predator fishes in the lake. This stock has remained and become a favorite target for anglers. In Japan, a landlocked variety termed black kokanee, or ""kunimasu"" in Japanese, was deemed to be extinct after 1940, when a hydroelectric project made its native lake in northern Akita Prefecture more acidic. The species seems to have been saved by transferring eggs to Saiko Lake, 500 kilometers to the south, however. This fish has been treated as a subspecies of sockeye "Oncorhynchus nerka kawamurae", or even an independent