Oncorhynchus nerka

Basic information
Scientific name	Oncorhynchus nerka	(No picture)
Common names	Sockeye salmon, Kokanee
Higher taxon	Salmonidae, Salmoniformes, Actinopterygii
Natural range	Freshwater in California, Canada, far eastern Russia, Chishima (Kuril) Islands, to Hokkaido, Japan, and N Pacific Ocean.
Habitat	Lakes, rivers, and ocean.

Invasion information
Range in Japan	Landlocked form (kokanee): Hokkaido (Shikotsuko and Toyako Lakes), Aomori (Towadako Lake), Tochigi (Chuzenjiko Lake), Kanagawa (Ashinoko Lake), Yamanashi (Saiko and Motosuko Lakes), and Nagano (Aokiko Lake) Prefs. Anadromous form (sockeye): Hokkaido (Nishibetsu and Abira Rivers).
Origin	Within Japan. Shikotsuko Lake population was from Akanko Lake, Hokkaido. The almost other introduced populations were from Shikotsuko Lake or Etorofu Is., southern Chishima (Kuril) Islands.
Date	Introduction from Akanko Lake to Shikotsuko Lake was in 1894.
Route	Deliberate: As fishery resource
Impact	Potentially: Predation on zooplankton. Competition with native fishes. Native organism(s) affected: Native fishes and zooplankton.
Regulation in Japan	Fishing of this species is prohibited by Hokkaido local government. In other lakes, fishing is prohibited in some season.
Introduced range in other countries	New Zealand (from Canada).

Reference

Notes

Froese & Pauly (eds) (2009) FishBase (Accessed on 2010-12-14) http://www.fishbase.org/
Kawanabe et al. (eds) (2002) Freshwater Fishes of Japan, 3rd ed.. Yama-kei Publishers, Tokyo (in Jpn)
Matsuzawa & Senou (2008) Alien fishes of Japan. Bun-ichi Sogo Shuppan, Tokyo (in Jpn)
Nakabo (2011) “Kunimasu” Oncorhynchus kawamurae (Pisces: Salmoidae), 70 years after extinction in Lake Tazawa, Akita Prefecture, Japan. TAXA. 30, 31-54 (in Jpn with English abst)
etc.

In Saiko Lake of Yamanashi Pref., another introduced salmon O. kawamurae was found in 2010. Oncorhynchus kawamurae, endemic to Tazawako Lake, Akita Pref., was assumed to be extinct in 1940s, and current living population is in Saiko Lake only. This species has sometimes been regarded as a subspecies of O. nerka.