The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Oncorhynchus nerka
Oncorhynchus nerka
(Sockeye Salmon)
Native Transplant

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Oncorhynchus nerka (Walbaum in Artedi, 1792)

Common name: Sockeye Salmon

Synonyms and Other Names: Kokanee salmon, when the population is landlocked

Taxonomy: available through www.itis.govITIS logo

Identification: Kokanee have a bluntly pointed, a conical head, "fang-like" teeth at the end of their jaws, and 30–40 fine rakers on their first gill arch. Males develop prominent snouts. Non-spawning kokanee are dark to greenish blue on the head and back, silver on the sides, silvery or white on the underbelly, and they exhibit no definite spotting on head, back, or tail. Spawning males develop a bright to olive green coloring on the heads with black on the snout and upper jaw, and a red coloring over their bodies and combinations of fins that vary between populations. Spawning females exhibit a less brilliant coloration than males. See also Moyle (1976a); Scott and Crossman (1973); Wydoski and Whitney (1979); Morrow (1980); Eschmeyer et al. (1983); Page and Burr (1991).

Size: 84 cm

Native Range: Arctic and Pacific drainages from Point Hope, Alaska, to Sacramento River drainage, California. Landlocked populations in Alaska, Yukon, British Columbia, Washington, and Oregon. Also in northeastern Asia (Page and Burr 1991).

Native range data for this species provided in part by NatureServe NS logo
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Oncorhynchus nerka are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AZ195819995Canyon Diablo; Havasu-Mohave Lakes; Lake Mead; Lower Colorado Region; San Francisco
AR196919691Bull Shoals Lake
CA1941201812Clear Creek-Sacramento River; East Walker; Lake Tahoe; Lower Klamath; Lower Pit; Mojave; Newport Bay; Trinity; Truckee; Upper Mokelumne; Upper Yuba; West Walker
CO1952201620Arkansas Headwaters; Big Thompson; Blue; Cache La Poudre; Colorado Headwaters; East-Taylor; North Platte Headwaters; Piedra; Rio Grande Headwaters; Roaring Fork; San Luis; South Platte; South Platte Headwaters; St. Vrain; Upper Arkansas; Upper Arkansas-Lake Meredith; Upper Dolores; Upper Gunnison; Upper North Platte; Upper San Juan
CT188019924Housatonic; New England Region; Outlet Connecticut River; Thames
ID1923201136Bear Lake; Big Lost; Big Wood; Boise-Mores; Brownlee Reservoir; C.J. Strike Reservoir; Camas; Clearwater; Coeur d'Alene Lake; Little Salmon; Little Wood; Lower Bear-Malad; Lower Clark Fork; Lower Henrys; Lower Kootenai; Lower North Fork Clearwater; Middle Bear; Middle Kootenai; North Fork Payette; Pacific Northwest Region; Pend Oreille Lake; Portneuf; Priest; Raft; Salmon Falls; South Fork Boise; South Fork Coeur d'Alene; South Fork Payette; South Fork Salmon; St. Joe; Teton; Upper Henrys; Upper Salmon; Upper Snake-Rock; Upper Spokane; Willow
ME194519734Lower Kennebec River; Maine Coastal; New England Region; St. George-Sheepscot
MA194620053Ashuelot River-Connecticut River; Housatonic; New England Region
MI196920004Lake Erie; Lake Huron; Lake Michigan; Lake Superior
MN197419741Big Fork
MO187819711Bull Shoals Lake
MT1914201227Belly; Bitterroot; Blackfoot; Cut Bank; Fisher; Flathead Lake; Fort Peck Reservoir; Judith; Lower Clark Fork; Lower Flathead; Lower Kootenai; Lower Yellowstone-Sunday; Middle Fork Flathead; Middle Kootenai; Musselshell; North Fork Flathead; Pend Oreille; St. Marys; Stillwater; Sun; Swan; Teton; Upper Milk; Upper Missouri; Upper Missouri; Upper Missouri-Dearborn; Upper Musselshell
NE195819992Lower North Platte; Salt
NV1936201910Granite Springs Valley; Havasu-Mohave Lakes; Lake Mead; Lake Tahoe; Middle Carson; Pyramid-Winnemucca Lakes; Truckee; Upper Owyhee; Walker Lake; West Walker
NM199020006Cimarron; Rio Chama; Rio Grande-Albuquerque; Upper Canadian; Upper San Juan; Upper San Juan
NY195019869Black; Hudson-Wappinger; Lake Champlain; Lake Ontario; Lower Hudson; Middle Hudson; Saranac River; Upper Hudson; Upper Susquehanna
NC199119911Upper Little Tennessee
OR197319973Little Deschutes; Pacific Northwest Region; Upper Rogue
PA192319864Lackawaxen; Lower Monongahela; Upper Susquehanna-Lackawanna; Upper Susquehanna-Tunkhannock
SD197419942Missouri Region; Rapid
TN195519552Lower Little Tennessee; Watauga, North Carolina, Tennessee
UT1922202011Bear Lake; Little Bear-Logan; Lower Weber; Price; Provo; Strawberry; Upper Colorado-Kane Springs; Upper Green-Flaming Gorge Reservoir; Upper Lake Powell; Upper San Juan; Upper Sevier
WA197919993Banks Lake; Colville; Puyallup
WI197620142Lake Michigan; Wolf
WY197020139Crow; Great Divide Closed Basin; New Fork; South Platte; Upper Green; Upper Green; Upper Green-Flaming Gorge Reservoir; Upper Green-Slate; Upper Laramie

Table last updated 6/18/2024

† Populations may not be currently present.

* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Ecology: Sockeye is an anadromous fish, beginning life in freshwater streams, swimming out to sea to feed and mature for 2 years, and then returning to the stream of its birth to spawn and die. This fish primarily eats plankton but is also known to feed on insects and bottom-dwelling organisms.

Means of Introduction: Authorized as stocking for sportfishing in most states. Stocked as forage in California (Moyle 1976b). Stocked in Arizona in 1967 (Rinne 1995). Cordone et al. (1971) gave the stocking history for Lake Tahoe.

Status: Established locally in some areas; failed in others. Failed in Tennessee. Rinne (1994) listed it as not established in Arizona. First found to be reproducing in the Great Lakes in Lake Huron in 1968 (Parsons 1973). Great Lakes introduction of kokanee in the 1960s and 70s resulted in naturally reproducing populations, but after stocking programs were discontinued, kokanee populations dwindled to the point where they currently persist only in northern Lake Huron, spawning in streams on Manitoulin island (Mills 1993). No longer present in Vermont (Hess, personal communication).

Impact of Introduction: Kokanee was introduced to compete with and reduce native Utah chub Gila atraria populations in Flaming Gorge Reservoir. However, it was found that under food-limiting conditions, the Utah chub was the superior competitor and was not affected by the kokanee (Teuscher and Luecke 1996). Seeley and McCammon (1966) gave a detailed discussion of impacts of kokanee on other species. Some of the impacts listed included: large kokanee populations can inhibit trout production because of competition for zooplankton; introductions of kokanee into small lakes can adversely affect even strongly established populations of rainbow trout; and late-run kokanee and brown trout may compete for the same spawning areas, especially in lower stream reaches. Introduced kokanee were at least partially responsible for the disappearance of three cladoceran species in Lake Tahoe (Morgan et al. 1978).

Sometimes stocked kokanee do not have an apparent negative effect. Some of the determining factors which may influence whether this species has negative impacts on a receiving ecosystem or not are waterbody size and depth, the forage base, stocking densities, other species present, and if early or late-run strains are stocked. Seeley and McCammon (1966) cautioned that kokanee's value as a forage fish may be overrated-the species may depress rather than bolster trout populations. Its presence may not enhance a fishery, especially in waters without a deep, cool, well-aerated hypolimnion. The species is not long-lived (2 years) and in many areas the fish is only accessible for fishing for short periods in the spring and fall. Therefore, the entire population may die off after only being briefly available to anglers.

Additionally, Weeber et. al  (2010) found that in the Deschutes River Basin, Oregon, groups of spawning kokanee did not scour the stream bed deeply enough to reach bull trout (Salvelinus confluentus) eggs.  Consequently, the data on bull trout fry emergence showed that kokanee redd superimposition did not affect bull trout egg-to-fry survival rates.

Remarks: Tyus et al. (1982) mapped the distribution the kokanee in the upper Colorado basin. Oncorhynchus nerka exhibits the greatest diversity of life history traits among pacific salmon (Burgner 1991). Taylor et al. (1996) found that populations of kokanee salmon share a more recent common ancestor with sockeye that reside downstream than kokanee that reside in another drainage basin. Mass spawning events of sockeye were found to greatly increase primary production in forested stream ecosystems (Johnston et al. 2004), while smolts were found to remove up to half of the nitrogen and phosphorus their parents transported in during those spawning events (Moore et al. 2004). In the 1960s, Great Lakes exotics including sea lamprey, alewives, and smelt were abundant while lake trout, a top predator, and many planktivorous fish such as cisco and various species of chub had drastically declined.

The addition of sockeye into the Great Lakes ecosystem was intended primarily to occupy the gap left by failing planktivorous fish populations and secondarily to function as a forage fish (Collins 1978). The two common names of O. nerka, "sockeye" and "kokanee" refer to anadromous and non-anadromous forms, respectively. In many cases populations of kokanee are more closely related to populations of sockeye that spawn downstream than they are to populations of kokanee in other geographic locations (Taylor et al. 1996).

References: (click for full references)

Bradley, W.G., and J.E. Deacon. 1967. The biotic communities of southern Nevada. Nevada State Museum Anthropological Papers No. 13, Part 4. 201-273.

Brown, P.J., H. Johnson, and A.V. Zale. 2011. Effect of rainbow trout size on response to rotenone and antimycin. North American Journal of Fisheries Management 31(6):1146-1152.

Burgner, R.L. 1991. Life History of Sockeye Salmon. In: C. Groot and L. Margolis eds. Pacific Salmon Life Histories. University of British Columbia Press, Vancouver, BC. pp. 3-117.

Champion, P., J. Clayton, and D. Rowe. 2002. Lake Manager's Handbook: Alien Invaders. New Zealand Ministry for the Environment, Wellington, New Zealand.

Clearwater, S.J., C.W. Hickey, and M.L. Martin. 2008. Overview of potential piscicides and molluscicides for controlling aquatic pest species in New Zealand. Science & Technical Publishing, New Zealand Department of Conservation, Wellington, New Zealand.

Collins, J.J. 1971. Introduction of kokanee salmon (Oncorhynchus nerka) into Lake Huron. Journal Fisheries Research Board of Canada 28(12):1857-1871.

Crawford, S.S. 2001. Salmonine introductions to the Laurentian Great Lakes: an historical review and evaluation of ecological effects. Canadian Special Publication of Fisheries and Aquatic Sciences No. 132. 205 pp.

Dawson, V.K., L.L. Marking, and T.D. Bills. 1976. Removal of toxic chemicals from water with activated carbon. Transactions of the American Fisheries Society 105(1):119-123.

Finlayson, B.J., R.A. Schnick, R.L. Cailteux, L. Demong, W.D. Horton, W. McClay, and C.W. Thompson. 2002. Assessment of antimycin A use in fisheries and its potential for reregistration. Fisheries 27(6):10-18.

Gilderhus, P.A. . 1972. Exposure times necessary for antimycin and rotenone to eliminate certain freshwater fish. Journal of the Fisheries Research Board of Canada 25(2):199-202.

GLMRIS. 2012. Appendix C: Inventory of Available Controls for Aquatic Nuisance Species of Concern, Chicago Area Waterway System. U.S. Army Corps of Engineers.

Hocutt, C.H., R.E. Jenkins, and J.R. Stauffer, Jr. 1986. Zoogeography of the Fishes of the Central Appalachians and Central Atlantic Coastal Plain. In C.H. Hocutt and E.O. Wiley, eds. The Zoogeography of North American Freshwater Fishes. pp. 161-212.

Holton, G.D. 1990. A Field Guide to Montana Fishes. Montana Department of Fish, Wildlife and Parks. Helena, MT. 104 pp.

Insider Viewpoint. 2001. Fishing Records – Nevada. Insider Viewpoint Magazine. 3 pp.

Johnston, N.T., E.A. MacIsaac, P.J. Tschaplinski, and K.J. Hall. 2004. Effects of the abundance of spawning sockeye salmon (Oncorhynchus nerka) on nutrients and algal biomass in forested  streams. Canadian Journal of Fisheries and Aquatic Sciences 61:384-403.

Kocik, J.F., and M.L. Jones. 1999. Pacific salmonines in the Great Lakes basin. In Taylor, W.W. and C.P. Ferreri, (Eds.). Great Lakes Fisheries Policy and Management: A Binational Perspective. Michigan State University Press, East Lansing, MI, pp. 455-488.

Lintermans, M. and T. Raadik. 2003. Local eradication of trout from streams using rotenone: the Australian experience. Pages 95-111 in Managing invasive freshwater fish in New Zealand: Proceedings of a workshop hosted by the Department of Conservation, Hamilton, New Zealand.

Miller, R.R., and C.H. Lowe. 1967. Part 2. Fishes of Arizona, p 133-151, In: C.H. Lowe, ed. The Vertebrates of Arizona. University of Arizona Press, Tucson, AZ.

Mills, E.L., J.H. Leach, J.T. Carlton, and C.L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. Journal of Great Lakes Research 19:1-54.

Moore, J.W., and D.E. Schindler. 2004. Nutrient export from freshwater ecosystems by anadromous sockeye salmon (Oncorhynchus nerka). Canadian Journal of Fisheries and Aquatic Sciences 61:1582-1589.

Morgan, M.D., S.T. Threlkeld, and C.R.Goldman. 1978. Impact of the introduction of kokanee (Oncorhynchus nerka) and opossum shrimp (Mysis relicta) on a subalpine lake. Journal Fisheries Research Board of Canada 35:1572-1579.

National Park Service. 2011. Natural Resource Fact Sheet--Exotic Fish Management. National Park Service.

Seeley, C.M. and G.W. McCammon. 1966. Kokanee. In: A. Calhoun, ed., Inland Fisheries Management. California Department of Fish and Game. pp. 274-294.

State of Oregon. 2000. Warm Water Game Fish Records. 7 pp.

Taylor, E.B., C.J. Foote, and C.C. Wood. 1996. Molecular evidence for parallel life-history evolution within a Pacific salmon (sockeye salmon and kokanee, Oncorhynchus nerka). Evolution 50:401-416.

Teuscher, D., and C. Luecke. 1996. Competition between kokanees and Utah chub in Flaming Gorge Reservoir, Utah-Wyoming. Transactions American Fisheries Society 125(4):505-511.

Tilmant, J.T. 1999. Management of nonindigenous aquatic fish in the U.S. National Park System. National Park Service. 50 pp.

Weeber, M.A., G.R. Giannico, and S.E. Jacobs. 2010. Effects of redd superimposition by introduced kokanee on the spawning success of native bull trout. North American Journal of Fisheries Management 30:47-54.

FishBase Summary

Author: Fuller, P., G. Jacobs, J. Larson, T.H. Makled, and A. Fusaro

Revision Date: 12/20/2019

Peer Review Date: 7/8/2014

Citation Information:
Fuller, P., G. Jacobs, J. Larson, T.H. Makled, and A. Fusaro, 2024, Oncorhynchus nerka (Walbaum in Artedi, 1792): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=915, Revision Date: 12/20/2019, Peer Review Date: 7/8/2014, Access Date: 6/18/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


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Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/18/2024].

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