Thaleichthys pacificus
Eulachon
NS
G5
Collection Details
Specimens
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Records
Taxonomic Hierarchy
Actinopterygii (Ray-finned Fishes)
Salmoniformes
Osmeridae (Smelts)
Thaleichthys
Thaleichthys pacificus (Eulachon)
Description
This species account was compiled from
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Characters
Body shape: elongated. 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. Striking features: none.
Distribution
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).
Habitat Associations
Freshwater, brackish, marine. pelagic-neritic. depth range 0-300 m. Found in: streams, estuaries, mangroves.
Biology
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.). Anadromous (Ref. 96339).
Max length: 34.0 cm TL; common length: 20.0 cm TL; max age: 5 years.
Reproductive mode: dioecism; fertilization: external; nonguarders (open water/substratum egg scatterers); parental care: none. 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).
IUCN Red List Status: Least Concern (LC), assessed 2012-03-01. Resilience: Medium (tm=2-6; tmax=5; K=0.34; Fec=17,000-60,000 Musick et al. 2000 (Ref. 36717)).
Commercial or Environmental Importance
Fisheries: commercial.
References
Scott, W.B. and E.J. Crossman (1973) Freshwater fishes of Canada. Bull. Fish. Res. Board Can. 184: xi+1-966.
Eschmeyer, W.N., E.S. Herald and H. Hammann (1983) A field guide to Pacific coast fishes of North America. Boston (MA, USA): Houghton Mifflin Company. xii+336 p.
Allen, M.J. and G.B. Smith (1988) Atlas and zoogeography of common fishes in the Bering Sea and northeastern Pacific. NOAA Tech. Rep. NMFS 66, 151 p.
Hart, J.L. (1973) Pacific fishes of Canada. Bull. Fish. Res. Board Can. 180:740 p.
Drake, A. and L. Wilson (1991) Eulachon, a fish to cure humanity. UBC Museum of Anthropology, Museum Note No. 32, 37 p., University of British Columbia, Canada.
Morrow, J.E. (1980) The freshwater fishes of Alaska. University of. B.C. Animal Resources Ecology Library. 248p.
Fadeev, N.S. (2005) Guide to biology and fisheries of fishes of the North Pacific Ocean. Vladivostok, TINRO-Center. 366 p.
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