Thaleichthys pacificus

Found only in the eastern Pacific, from Monterey Bay, California, to Nushagak River and Pribilof Islands, Bering Sea, Alaska (Lee et al. 1980, Page and Burr 1991). Distribution coincides closely with coastal temperate rainforest, although there may not be a functional linkage (Hay and McCarter 2000). Historically spawned in the Sacramento River system and farther south along the California and Baja California coast but have been extirpated from those locations, occurring now only as far south as Monterey Bay (one record from this location) and in the Klamath River in California, rivers in Oregon and the Columbia River in Washington (Hay and McCarter 2000, Mecklenburg et al. 2002, Willson et al. 2003). In Alaska, seasonally abundant in most major drainages from Southeast Alaska west to Cook Inlet and become less abundant westward toward the Aleutian Islands and the Pribilof Islands in the Bering Sea (Fritz et al. 1993, Willson et al. 2003).

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: Found only in the eastern Pacific, from Monterey Bay, California, to Nushagak River and Pribilof Islands, Bering Sea, Alaska (Lee et al. 1980, Page and Burr 1991). Distribution coincides closely with coastal temperate rainforest, although there may not be a functional linkage (Hay and McCarter 2000). Historically spawned in the Sacramento River system and farther south along the California and Baja California coast but have been extirpated from those locations, occurring now only as far south as Monterey Bay (one record from this location) and in the Klamath River in California, rivers in Oregon and the Columbia River in Washington (Hay and McCarter 2000, Mecklenburg et al. 2002, Willson et al. 2003). In Alaska, seasonally abundant in most major drainages from Southeast Alaska west to Cook Inlet and become less abundant westward toward the Aleutian Islands and the Pribilof Islands in the Bering Sea (Fritz et al. 1993, Willson et al. 2003).

North Pacific: west of Saint Matthew Island and Kuskokwim Bay in the Bering Sea, and Bowers Bank in the Aleutian Islands to Monterey Bay, California, USA. Populations from northern British Columbia are separate from those in the Fraser River (Ref. 10276).

North Pacific.

Found near shore and in coastal inlets and rivers (Ref. 2850). Possibly to 625 m depth (Ref. 6793). Spends most of its life in the sea, returning to freshwater streams to spawn (Ref. 27547). There is evidence of return to natal streams (Ref. 10276). May migrate up to 160 km upstream. Feeds on plankton and only while at sea (11699, 10276). Excellent food fish and source of oil (15% body wt.).

Dorsal spines (total): 0; Dorsal soft rays (total): 10 - 13; Analspines: 0; Analsoft rays: 18 - 23; Vertebrae: 65 - 72

Length: 30 cm

Maximum size: 300 mm TL

34.0 cm TL (male/unsexed; (Ref. 56527)); max. reported age: 5 years (Ref. 12193)

Distinguished by the large canine teeth on the vomer and 18 to 23 rays in the anal fin (Ref. 27547). Adipose fin sickle-shaped; paired fins longer in males than in females; all fins with well developed breeding tubercles in ripe males which are poorly developed or absent in females (Ref. 27547). Adult coloration is brown to blue on back and top of the head, the sides lighter to silvery white, and the ventral surface white; speckling is fine, sparse and restricted to the back; peritoneum is light with black speckles (Ref. 6885). Fins transparent, pectorals and caudal often dusky (Ref. 27547). During spawning, male fish has a distinctly raised ridge along the middle of the body and a rough texture, differentiating it from the female which is smaller, smoother and shinier.

Habitat and Ecology

Systems

• Freshwater
• Marine

Habitat Type: Freshwater

Comments: Nearshore ocean bottom, coastal inlets. Adults live at moderate sea depths (commonly 20-200 m but have been recorded as deep as 625 m) in echo-sounding layer not far from shore; young apparently occur in deeper water (Lee et al. 1980, Page and Burr 1991, Willson et al. 2003). Spawns in coastal freshwater streams over bottoms of silt, sand, gravel, cobble or detritus but apparently prefer bar and riffle habitat containing sand or pea-gravel, seldom more than a few miles inland (Estes and Vincent-Lang 1984, Willson et al. 2003). Presence of spring freshets is a factor common to nearly all spawning streams or rivers; typically characteristic of rivers that drain large snowpacks or glaciers (Hay and McCarter 2000, Willson et al. 2003).

pelagic-neritic; anadromous (Ref. 51243); freshwater; brackish; marine; depth range 0 - 300 m (Ref. 6793)

Depth range based on 4719 specimens in 1 taxon.
Water temperature and chemistry ranges based on 2583 samples.

Environmental ranges
  Depth range (m): 8.5 - 341.5
  Temperature range (°C): 2.936 - 8.705
  Nitrate (umol/L): 13.007 - 35.568
  Salinity (PPS): 32.561 - 33.970
  Oxygen (ml/l): 2.013 - 6.411
  Phosphate (umol/l): 1.398 - 2.627
  Silicate (umol/l): 21.984 - 76.047

Graphical representation

Depth range (m): 8.5 - 341.5

Temperature range (°C): 2.936 - 8.705

Nitrate (umol/L): 13.007 - 35.568

Salinity (PPS): 32.561 - 33.970

Oxygen (ml/l): 2.013 - 6.411

Phosphate (umol/l): 1.398 - 2.627

Silicate (umol/l): 21.984 - 76.047
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Depth: 0 - 300m.
Recorded at 300 meters.

Habitat: pelagic.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

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: No. No populations of this species make annual migrations of over 200 km.

Anadromous. Migrates short distances up coastal streams to spawn.

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.

Found near shore and in coastal inlets and rivers (Ref. 2850). Possibly to 625 m depth (Ref. 6793). Spends most of its life in the sea, returning to freshwater streams to spawn (Ref. 27547). There is evidence of return to natal streams (Ref. 10276). May migrate up to 160 km upstream. Feeds on plankton and only while at sea (11699, 10276). Ecotoxicology of this species has been studied by various authors indicating that it is a potential integrator of low-level contaminants (Ref. 7355 & 7469).

Comments: Eats crustaceans. Adults do not feed while in fresh water. Mainly a particulate feeder as opposed to a filter feeder, consuming primarily marine euphausiid crustaceans (Thysanoessa spp.) (Hay and McCarter 2000). Young fish eat mostly copepod larvae, phytoplankton, copepods and other zooplankton, and smaller eulachon larvae; diet of juvenile fish consists of euphausiids, like adults (Morrow 1980).

A valuable food source for many animals because of extremely high oil content (about 20%, or 4-5 times higher than most other fish of comparable size) (Payne et al. 1999 in Hay and McCarter 2000). Predators include sea birds and ducks, marine and terrestrial mammals, and humans (Lee et al. 1980, Willson et al. 2003). Predators often congregate at eulachon spawning runs. Used historically and currently for an essential source of oil and food by Native Americans throughout their range (Drake and Wilson 1991). Called candlefish because a dried fish threaded with a wick will burn like a candle (Hay and McCarter 2000).

Comments: Spawning migrations usually occur in April and May, often corresponding to high tides; spawning activity occurs at night (Willson et al. 2003).

The spawning run from the sea to freshwater streams begins when river temperature rises to about 4.4° but the fish stop running if temperature exceeds 7.8°C. Males predominate the early part of the run, but their numbers are equalled or exceeded by females later (Ref. 10276, 11699). Adults usually die after spawning but some move back to the sea and return to spawn a second time (Ref. 1998). Upon hatching, larvae are found near the bottom and are soon carried downstream to salt water and eventually found in the scattering layer of coastal waters (Ref. 27547).

Maximum longevity: 5 years (wild)

Spawns in the spring. Females produce 17,000- 40,000 eggs (Scott and Crossman 1973); average fecundity is around 25,000 eggs per female (Drake and Wilson 1991). Eggs incubate in sediment for 2-3 weeks, depending on water temperature, then hatch and larvae are carried downstream to the sea (Willson et al. 2003). Most adults die soon after spawning, may live 5 years. Generally semelparous, with sexual maturity reached at around age 3 or 4 (Hay and McCarter 2000, Willson et al. 2003). Spawning occurs at night, and males and females must synchronize activity closely because eulachon sperm remain viable for only a short time, possibly minutes (Hay and McCarter 2000, Willson et al. 2003). Spawning migration timing is variable and appears to be related to water temperature and the occurrence of high tides. Runs occur from February to June throughout species range, but generally occur in April or May; in some rivers more than one run occurs (Willson et al. 2003).

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

Canada

Rounded National Status Rank: N2 - Imperiled

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Other Considerations: Able to rebound from periods of low abundance (NMFS 1999). Catch data are not necessarily a reliable measure of population abundance or even eulachon presence/absence (NMFS 1999).

Population

Population Trend

Major Threats

Least Concern (LC)

Comments: Threatened by overfishing in subsistence and commercial fisheries, continued/increased bycatch in commercial groundfish and shrimp fisheries, industry pollution of freshwater and marine habitats, human impact on spawning habitat (logging, dredging, diversions, etc.) and climate change (Hay and McCarter 2000).

Subsistence harvest is widespread throughout this species' range, is mostly unregulated, and could potentially slow recovery of declining populations. Bycatch of eulachon in commercial offshore groundfish and shrimp trawl fisheries may be substantial; shrimp trawling, especially, has increased in the last decade (Hay and McCarter 2000).

Threats to eulachon habitat include diversions/dams, logging, dredging and industrial pollution of streams and rivers, all of which may affect water volume, temperature and sediment levels in spawning habitat. Native communities in Southeast Alaska have noted declining eulachon harvests and expressed concern about the effects of log rafting and pollution on fish habitat (Drake and Wilson 1991).

Recent changes in ocean climate, including increased surface water temperatures, have been recognized in the Gulf of Alaska and elsewhere in the species range, and have resulted in a general reorganization of fish communities in some areas (Anderson and Piatt 1999, Hay and McCarter 2000). High water temperatures can be lethal to cold-water acclimated fish. A study of 5°C-acclimated eulachon immersed in 11°C water for several days resulted in 50% mortality and spawning failure (Blahm and McConnell 1971 in Willson et al. 2003).

Conservation Actions

fisheries: commercial

Stewardship Overview: Continued protection of spawning habitat through restricted dredging and management of logging and industrial water pollution. Limit bycatch in commercial shrimp fisheries by conducting catch-monitoring assessments and mandating area closures when bycatch limits are reached. Also, require use of fishery observers and selectivity devices which allow passive exit of bycatch species through escape panels (i.e., the Nordmore grid).