Oncorhynchus nerka

The Sockeye or Red Salmon (Oncorhynchus nerka) is native to northeastern Asia and, in North America, Arctic and Pacific drainages from Point Hope, Alaska, to the Sacramento River drainage in California. Landlocked populations are found in Alaska, Yukon Territory, British Columbia, Washington, and Oregon. This species is relatively common in the northern part of its North American range, but rarer south of the Columbia River drainage. Although it has been widely stocked, most transplant attempts have failed to establish populations. (Page and Burr 1991)

At different periods in the life cycle, Sockeye Salmon are found in the open ocean and, typically, in lakes, which they reach by migrating up coastal streams. Landlocked Sockeye Salmon are known as Kokanee. At sea, these fish are metallic blue and silver, but spawning (breeding) adults are very distinctively colored, turning bright red with a green head. Adults reach a size of around 84 cm in length. (Page and Burr 1991).

Approximately the first half of a Sockeye Salmon's four to six year lifespan is spent in freshwater, while the second half is spent foraging in estuarine and marine waters of the Pacific Ocean. Sockeye Salmon migrate upstream to breed just once, then die. For detailed information on the biology and status of this species, including conservation issues, see this resource from the NOAA Fisheries Office of Protected Resources.

Epipelagic (Ref. 58426). There are two forms, the anadromous form known as the sockeye and the landlocked form (with a much smaller maximum size) known as the kokanee (Ref. 27547). Upon emergence from gravel, fry at first tends to avoid light, hiding during the day and emerging at night (Ref. 27547). In some populations, sockeye fry go to the sea during their first summer but most spend one or two (rarely three or four) years in a lake before migrating (Ref. 30333). In a few streams of the Copper River drainage in Alaska, young sockeye stay in the stream (Ref. 27547). Once in the lake, the young spend a few weeks inshore, feeding largely on ostracods, cladocerans and insect larvae. The fish then become pelagic and move offshore, where they feed on plankton in the upper 20 m or so (Ref. 27547). Seaward migration follows with the young individuals first staying fairly close to shore, feeding mainly on zooplankton, but also on small fishes and insects (Ref. 30343, 30346). With growth, they head out to sea and fish become important in the diet (Ref. 27547). Kokanee are confined to lake-stream systems, and most of its life is spent in the lake (Ref. 27547). They feed mainly on plankton, but also take insects and bottom organisms (Ref. 1998). Kokanee, wherever they are native, have been derived from anadromous populations, and each kokanee population apparently has evolved independently from a particular sockeye run (Ref. 30338, 30339). Offspring of kokanee occasionally become anadromous, and sockeye offspring occasionally remain in freshwater (Ref. 27547). Lifespan of the kokanee varies from two to seven years in different stocks (Ref. 27547). The sockeye is one of the most commercially important Pacific salmons; the kokanee is primarily a sport fish but also makes excellent food and in some areas well regarded as food for large trout (Ref. 27547). Marketed fresh, dried or salted, smoked, canned, and frozen; eaten steamed, fried, broiled, microwaved, and baked (Ref. 9988). The Alaska Salmon fishery of this species has been certified by the Marine Stewardship Council (http://www.msc.org/) as well-managed and sustainable (http://www.msc.org/html/content_485.htm).

Sockeye salmon, Oncorhynchus nerka, are native to the western coast of North America in the Pacific Ocean. They can be located as far north as northern Alaska and as far south as northern California. During the mating season, Sockeye salmon travel inland as far as mid-west Idaho. Populations of this species have also been introduced in some areas of Asia and Russia.

Biogeographic Regions: nearctic (Native ); palearctic (Introduced ); pacific ocean (Native )

Other Geographic Terms: holarctic

The current distribution of Oncorhynchus nerka extends from approximately 45–70°N to 140°E–125°W longitude. The species has been recorded from Russia, United States, Canada, and Japan, although the Japanese populations are likely to have resulted from introductions; Japan is therefore not considered to be part of this species' natural range.

See the additional supporting documentation (particularly Figures 1 & 2, and Appendices 1 & 2) for details on the range of this species and of each of the 98 subpopulations identified. Follow the link below for a PDF of the additional supporting documentation.

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: During oceanic feeding and maturation, this salmon ranges throughout the North Pacific Ocean, Bering Sea, and eastern Sea of Okhotsk north of 40 degrees north latitude; there is considerable intermingling of Asian and North American populations, and of North American populations from Bering Sea and Gulf of Alaska streams; the range shifts southward for winter, northward during warmer months. Natural lake populations occur in Japan, former USSR, Alaska, Washington, Idaho, Oregon, Yukon, and British Columbia. Anadromous forms occur in Asia from Hokkaido, Japan, to the Anadyr River (spawning mainly on the Kamchatka Peninsula); in North America, anadromous populations range from the Sacramento River, California, north to Point Hope, Alaska (common in north, rare south of Columbia River drainage). Major Alaskan spawning areas are in tributaries and lakes of the Kenai, Chignik, Naknet, Kuichak, Wood, and Kodiak Island river systems. South of Alaska in the Pacific Northwest, the major spawning river is the Fraser River system in British Columbia, with smaller runs in the Baker, Columbia, Cedar, Quinalt, and Ozette rivers in Washington. The Fraser River includes a number of important nursery lakes (Cultus, Adams, Harrison, Horsefly, Shuswap, and Quesnel) and many tributaries that support the major portion of the Pacific Northwest population. In eastern Washington, major nursery lakes for Columbia River are Lake Wenathchee and Osoyoos Lake. In western Washington, major nursery lakes are Quinalt Lake, Ozette Lake, Baker Lake, and Lake Washington. In a 1996 survey of populations in the contiguous U.S., one healthy native stock was identified (Wenatchee River, Washington). The kokanee (lake-stream form) has been introduced in many western states and elsewhere, but most transplants have been unsuccessful in establishing self-sustaining populations.

Historic Range:
North Pacific Basin from U.S.A. (CA) to Russia

North Pacific: northern Japan to Bering Sea and to Los Angeles, California, USA (Ref. 2850). Landlocked populations in Alaska, Yukon Territory and British Columbia in Canada, and Washington and Oregon in USA.

North Pacific, introduced elsewhere.

When sockeye salmon hatch, they lack pigment and thus color. As they grow into fry, they become green and can have black spots. Sockeye salmon are typically blue in color until they reach reproductive age, when they brighten in color; their bodies turn read and their heads green. Additional distinctive markings appear on the head of males and sides of females during the spawning period. When ready to reproduce, sockeye salmon weigh 1 to 4 kg and measure on average 63 cm in length. Sockeye salmon are commonly misidentified. The otolith, or inner ear, of this species is distinct in size and shape from other members of the genus g. Oncorhynchus. This, however, is not always exact as there can be overlap among species in addition to intraspecific differences.

Range mass: 1 to 4 kg.

Average length: 63 cm.

Other Physical Features: ectothermic ; bilateral symmetry

Sexual Dimorphism: male more colorful

Dorsal spines (total): 0; Dorsal soft rays (total): 11 - 16; Analspines: 0; Analsoft rays: 13 - 18; Vertebrae: 56 - 67

Length: 71 cm

Maximum size: 840 mm TL

84.0 cm TL (male/unsexed; (Ref. 5723)); 71 cm (female); max. published weight: 7,710 g (Ref. 40637); max. reported age: 8 years (Ref. 72462)

Both the sockeye and the kokanee are distinguished by the long, fine, serrated, closely spaced gill rakers on the first arch that number between 30 and 40, and by its lack of definite spot on the back and tail (Ref. 27547). Body fusiform, streamlined, laterally compressed, body depth moderate, slightly deeper in breeding males (Ref. 6885). Head bluntly pointed, conical, eye rather small, position variable with sex and condition; snout rather pointed (Ref. 6885). Lateral line straight (Ref. 27547). Pelvic fins with axillary process; caudal emarginate (Ref. 27547). Pre-spawning fish are dark steel blue to greenish blue on the head and back, silvery on the sides and white to silvery on the belly; no definite spots on the back, although some individuals may have dark speckling and irregular marks on the dorsal fin (Ref. 27547). At spawning, the head of the males becomes bright to olive green, with black on the snout and upper jaw; the adipose and anal fins turn red and the paired fins and tail generally become grayish to green or dark; females are generally less brilliantly colored than males (Ref. 27547). Various populations may show less brilliant colors, and a few turn dull green to yellowish, with little if any red (Ref. 27547).

Known from seamounts and knolls

Known from seamounts and knolls

Sockeye salmon are born in lakes, rivers, or streams, which are calmer than the Pacific Ocean. After fry, or young salmon, develop, they migrate to the Pacific Ocean where they spend most of their life. They are generally found at depths of 15 to 33 m.

Range depth: 15 to 33 m.

Habitat Regions: temperate ; polar ; saltwater or marine ; freshwater

Aquatic Biomes: pelagic ; lakes and ponds; rivers and streams; coastal ; brackish water

Other Habitat Features: estuarine

Habitat and Ecology

Systems

• Freshwater
• Marine

Habitat Type: Freshwater

Comments: Nonbreeding adult sockeye salmon are oceanic, with many occurring in nutrient-rich waters of Alaska and the arctic. Kokanee do best in large, cold, mountain lakes (Sigler and Sigler 1987), where the presence of well-oxygenated water is essential (Sublette et al. 1990).. Water temperatures above 60 degrees F (about 15.5 C) lead to significant mortality, especially among the young (see Sublette et al. 1990). Young are not often found in estuarine or inshore waters after reaching the marine environment (Pauley et al. 1989).

Kokanee usually spawn in tributary stream of lake, often in riffle over gravel substrate; sometimes along gravelly shore of lake where seepage outflows, springs, or wind-induced waves occur. Sockeye move up coastal rivers and spawn in streams. Female constructs a redd (several nesting pockets) in gravel (usually) or sand bottom.

pelagic-oceanic; anadromous (Ref. 51243); freshwater; brackish; marine; depth range 0 - 250 m (Ref. 50550)

Depth range based on 4 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0 - 122

Graphical representation

Depth range (m): 0 - 122
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Depth: 0 - 250m.
Recorded at 250 meters.

Habitat: pelagic.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Anadromous forms migrate from ocean waters up coastal streams and rivers to spawn in natal waters; spend 1-4 years (usually 2 years) in ocean, 2 years in freshwater; ascend river, spend 1-8 months in lake, then move to natal spawning area. Many non-anadromous populations move from lakes into tributary streams to spawn, some remain in lakes. Enters spawning rivers from late spring to midsummer, depending on the population.

Anadromous. Fish that ascend rivers to spawn, as salmon and hilsa do. Sub-division of diadromous. Migrations should be cyclical and predictable and cover more than 100 km.

While in the ocean, sockeye salmon primarily consume zooplankton. In freshwater environments, they are known to eat insects, and, when upstream, occasionally snails.

Animal Foods: insects; mollusks; zooplankton

Primary Diet: planktivore

Epipelagic (Ref. 58426). There are two forms, the anadromous form known as the sockeye and the landlocked form (with a much smaller maximum size) known as the kokanee (Ref. 27547). Upon emergence from gravel, fry at first tends to avoid light, hiding during the day and emerging at night (Ref. 27547). In some populations, sockeye fry go to the sea during their first summer but most spend one or two (rarely three or four) years in a lake before migrating (Ref. 30333). In a few streams of the Copper River drainage in Alaska, young sockeye stay in the stream (Ref. 27547). Once in the lake, the young spend a few weeks inshore, feeding largely on ostracods, cladocerans and insect larvae. The fish then become pelagic and move offshore, where they feed on plankton in the upper 20 m or so (Ref. 27547). Seaward migration follows with the young individuals first staying fairly close to shore, feeding mainly on zooplankton, but also on small fishes and insects (Ref. 30343, 30346). With growth, they head out to sea and fish become important in the diet (Ref. 27547). Kokanee are confined to lake-stream systems, and most of its life is spent in the lake (Ref. 27547). They feed mainly on plankton, but also take insects and bottom organisms (Ref. 1998). Kokanee, wherever they are native, have been derived from anadromous populations, and each kokanee population apparently has evolved independently from a particular sockeye run (Ref. 30338, 30339). Offspring of kokanee occasionally become anadromous, and sockeye offspring occasionally remain in freshwater (Ref. 27547). Lifespan of the kokanee varies from two to seven years in different stocks (Ref. 27547).

Comments: Kokanee feed on zooplankton. Young sockeye eat primarily planktonic crustaceans. At sea, young sockeye feed on zooplankton, small fishes and insects; as they grow they eat more fish.

Sockeye salmon are host to a variety of parasites, which are generally found within the kidney. Most of these parasites release spores when in freshwater where excretion of water by sockeye salmon is high. These parasites include Myxidium salvelini and Parvicapsula minibicornis, both myxosporeans. Sockeye salmon also contribute to the diet of black bears and brown bears.

Commensal/Parasitic Species:

• Myxidium salvelini
• Parvicapsula minibicornis

Adult sockeye salmon are easily spotted and caught because of their size, and they are eaten by bears, including brown bears and black bears, and birds, such as the mew gull. Predators of frys (young sockeye salmon) include lake trout, squawfish, and mountain whitefish. Most predation occurs in streams and rivers. As frys, sockeye salmon can often escape predators because of their smaller size. Humans also consume a considerable about of sockeye salmon.

Known Predators:

• Brown Bear Ursus arctos
• Black Bear Ursus americanus
• Bald Eagle Haliaeetus leucocephalus
• Rainbow Trout Oncorhynchus mykiss)
• Cutthroat Trout Oncorhynchus clarkii clarkii
• Sculpins Cottus asper
• Mountain Whitefish Prosopium williamsoni
• Arctic Turns Sterna paradisaea
• Lake Trout Salvelinus namaycush
• Squawfish Ptychocheilus oregonensis
• Mew Gulls Larus canus
• Humans Homo sapiens

Whirling Disease 3. Parasitic infestations (protozoa, worms, etc.)

Enteric Redmouth Disease. Bacterial diseases

Life cycle of sockeye similar to kokanee except sockeye matures in the ocean rather than lakes. Kokanee often travels in large schools. (Sigler and Sigler 1987). Two studies each reported survival rate of 4-20% for marine portion of life cycle (see Pauley et al. 1989). Northern squawfish and rainbow trout may be important predators on young in some lakes. Schools of young in lakes disperse as dusk approaches, reform after dawn (Pauley et al. 1989). In Montana, the introduction of opossum shrimp (MYSIS RELICTA) was followed by an abrupt decline in the kokanee population, apparently due to zooplankton decline caused by shrimp predation (Spencer et al. 1991).

The eyes of sockeye salmon are located on opposite sides of their head, and they thus have a greater field of vision than animals with two eyes facing forward. The spectrum of visibility of sockeye salmon includes color, from indigo to red, as well as ultraviolet light. Members of this species have nostrils and an enhanced sense of smell. This also adds to their sense of taste. Additionally, sockeye salmon have lateral lines, which detect vibrations, allowing them to hear.

Perception Channels: visual ; ultraviolet; tactile ; vibrations ; chemical

Comments: Kokanee: feeding generally heaviest from sundown to dark (Sigler and Sigler 1987). Young sockeye feeding heaviest in afternoon, lightest at night and early morning (Pauley et al. 1989).

Sockeye salmon follow the developmental patterns of many pacific salmon. Eggs are externally fertilized by the male. Embryos begin as a single cell with a yolk. After this cell divides, the resulting cells differentiate into specific body type cells until the fetus is developed and ready to hatch, at which time it is called an alevin. Alevins carry the yolk on the anterior end of their body and appear to be clear because they have no pigment. As alevins develop into adults, the yolk shrinks and coloration occurs. Sex of sockeye salmon is initially difficult to determine, but is easily determined later in life by their body shape and coloration.

Development - Life Cycle: metamorphosis ; indeterminate growth

Adult sockeyes return to natal streams to spawn. This occurs during summer and fall and as late as December in the southern part of the range. The female selects a site, usually with gravel bottom, and digs a nest. During nest building, the female is attended by a dominant male and a few subordinate males. At this stage, females tend to be aggressive toward other females and subordinate males; males are aggressive toward other males. Between digging acts, the female will rest over the pit while the dominant male courts her. Once the nest is completed, the female enters the nest, followed immediately by the dominant male who comes close beside her. Their mouths gape, and the pair vibrates to release eggs and sperm. One or more subordinate males may come to the other side of the female and join in the spawning. The female then moves to the upstream edge of the nest and digs again, covering the old nest, at the same time creating a new one just upstream from the previous one. A female normally needs 3 to 5 days to deposit all her eggs and utilizes 3 to 5 nests for this purpose. She may spawn with several dominant males. A male may breed with several females. All adult sockeye die after spawning (Ref. 27547).Reproductive strategy: synchronous ovarian organization, determinate fecundity (Ref. 51846).

The average lifespan for sockeye salmon in the wild is 4 to 5 years. The oldest salmon caught was 8 years of age. Typically, sockeye salmon die after mating.

Range lifespan
Status: wild: 8 (high) years.

Typical lifespan
Status: wild: 4 to 5 years.

Sockeye salmon mate seasonally. Females lay their eggs and are then to select a mate. Males are chosen after they have come along her side and presented themselves multiple times. They are judged on their color and size. During this process, males can be attacked by females and other males. Larger dominant males reproduce more often than other males and, because sockeye salmon are polygynous, the dominant male can mate with many females. Some subordinate males may not have the opportunity to mate at all.

Mating System: polygynous

Sockeye salmon breed from July to October, although some members of this speices located in the southern-most point of their geographic range have been known to breed into December. When females arrive, they create a nest in the gravel in which they lay their eggs. After fertilization, eggs stay in the gravel nest for 32 to 42 days. Females produce 47 to as many as 206 offspring. Sockeye salmon are independent when hatched and are able to reproduce at 4 to 5 years of age.

Breeding interval: Sockeye salmon breed once a year.

Breeding season: Sockeye salmon generally breed from July to October.

Range number of offspring: 47 to 206.

Range gestation period: 32 to 42 days.

Average time to independence: 0 years.

Range age at sexual or reproductive maturity (female): 4 to 5 years.

Average age at sexual or reproductive maturity (female): 4 to years.

Range age at sexual or reproductive maturity (male): 4 to 5 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); broadcast (group) spawning; oviparous

Mothers invest time creating gravel nests, in which eggs incubate. After fertilization, however, the newly hatched alevin have no parental investment.

Parental Investment: no parental involvement; female parental care ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female)

Anadromous forms migrate from ocean waters up coastal streams and rivers to spawn in natal waters. They spend 1-4 years (usually 2 years) in the ocean before ascending streams (mainly in summer but some stocks as early as winter). Many stocks spawn in fall (peak often in October or November), but spawning extends into winter in some areas. Spawning sites often are in gravel riffles, sometimes along gravelly shores of lakes where seepage outflows, springs, or wind-induced waves occur. Eggs hatch in 6-9 weeks, depending on temperature, and larvae emerge 2-3 weeks later. Sockeye fry move upstream or downstream to nursery lakes, where the young spend 1-2 years (up to 3 or rarely 4 years in some areas of Alaska; usually 1 year in British Columbia) before going to sea, usually in spring; some populations use stream areas for rearing and may migrate to the sea soon after emergence.

Many non-anadromous (kokanee) populations move from lakes into tributary streams to spawn, though some remain in lakes. They enter spawning streams from late spring to midsummer, depending on the population. Kokanee spawn in different areas from August to February, at temperatures of 40-55 F.

Although listed as a species of least concern by the IUCN Red List, the U.S. Fish and Wildlife Service Species Report listed O. nerka as endangered in 1992. In some areas, sockeye salmon are only listed as threatened, as populations have stabilized. Many programs have been implemented to prevent over-fishing and to rejuvenate sockeye populations in areas where over-fishing has occurred.

US Federal List: endangered; threatened

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
  (IUCN 2008)
• 2008
  Least Concern

Canada

Rounded National Status Rank: N4 - Apparently Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Current Listing Status Summary

Status: Endangered
Date Listed: 01/03/1992
Lead Region:   National Marine Fisheries Service (Region 11)   
Where Listed: U.S.A. (Snake River, ID stock wherever found.)

Status: Threatened
Date Listed: 03/25/1999
Lead Region:   National Marine Fisheries Service (Region 11)   
Where Listed: U.S.A. (Ozette Lake, WA)

Population detail:

Population location: U.S.A. (Snake River, ID stock wherever found.)
Listing status: E

Population location: U.S.A. (WA) all naturally spawned population in Ozette Lake and its tributary streams
Listing status: T

For most current information and documents related to the conservation status and management of Oncorhynchus nerka, see its USFWS Species Profile

Population

Population Trend

Major Threats

Comments: Decline is due to dams that blocked migration, mainstem passage mortality at Columbia and Snake river dams, overutilization in commercial fisheries, and habitat modification (see Nehlsen et al. 1991). Sockeye in the Deschutes River (Oregon) were largely eradicated by dam construction (small anadromous run is maintained by incidental passage of smolts from a resident kokanee population) (Nehlsen et al. 1991). In the Puget Sound area, decline of the Baker River sockeye population has been attributed to upstream and downstream passage problems as a result of dam construction (Nehlsen et al. 1991). Lake Ozette sockeye run on the Washington coast declined because of logging and overfishing in the 1940s and 1950s (Nehlsen et al. 1991).

The decline and persistent low abundance of the Rivers Inlet population in British Columbia apparently was due to poor marine survival, and not due to a decline in juvenile abundance (McKinnell et al. 2001).

Least Concern (LC)

Conservation Actions

Management Requirements: Allendorf et al. (1997) proposed criteria for prioritizing Pacific salmon stocks for conservation; data limitations introduce subjectivity into the process, so expert judgment and peer review should be incorporated into the process.

Needs: See Nehlsen et al. (1991) for general protection and management recommendations for anadromous salmonids. See Thomas et al. (1993) for information on habitat management for this and other at-risk fish species in the Pacific Northwest. Waples and Teel (1990) emphasized the importance of monitoring the genetic consequences of the large-scale artificial propagation programs involving Pacific salmon (see also Waples 1990). Meffe (1992) gave reasons why the hatchery approach to recovery ultimately will fail, and he emphasized that overharvest and habitat destruction need to be addressed in a major landscape-level effort.

Salmon, including sockeye salmon, are caught in and destroyed by hydroelectric dams when they attempt to swim through to spawn. This decreases salmon populations and thus availability for fishing.

Sockeye salmon are commonly fished and are the most common species of salmon caught around British Columbia and Alaska.

Positive Impacts: food

Comments: Important commercial and sport fish; commercially important from Columbia River to Bristol Bay, Alaska; most valuable commercial fishery in both Alaska and British Columbia; important as subsistence and ceremonial fish to indigenous peoples of Alaska, British Columbia, and Washington. See Pauley et al. 1989 for many details on commercial fishery. Has been used in carcinogen testing (Metcalfe 1989).

fisheries: highly commercial; aquaculture: commercial; gamefish: yes; aquarium: public aquariums; price category: very high; price reliability: questionable: based on ex-vessel price for species in this genus