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Thaleichthys pacificus (Richardson, 1836)
Eulachon
Family: Osmeridae
Introduction to the Fish

Photograph

© Aaron Baldwin     (Photo ID #37339)

Map


Click on the map to view a larger version.
Source: Distribution map provided by Don McPhail for E-Fauna BC

Introduction


The Eulachon is a small (15-20 cm long), herring-sized, silver species of fish in the Osmeridae or smelt family that is found along the Pacific Coast from Alaska to California. It is a short-lived anadromous species that spends much of its life in the ocean, but returns to spawn in high numbers in coastal rivers in coarse sand or gravel. Most spawn in rivers that drain glaciers (Stoffels 2001). According to Fisheries and Oceans Canada (2009), "Within BC, they have been documented spawning in 33 rivers, but may only use 14-15 on a sustained basis. Of these, the major river systems where eulachon return to spawn are the Fraser, Skeena, Nass, and Klinaklini". The biology of this species is not fully known, however, Stoffels (2001) provides some detail: 1) in the ocean, this species is toothed, however spawning adults have no or much reduced teeth which may indicate that teeth are reabsorbed prior to spawning, 2) following spawning, eggs hatch in two or three weeks, and larvae are carried downriver, possibly spending several months in estuaries, 3) they spend three or four years in the ocean before returning to spawn.

Although this species has increased in numbers in coastal areas, there is a reported overall decline in BC rivers since 1994, and the species has disappeared from some rivers (Fisheries and Oceans Canada 1999). Potential reasons for this decline may include altered and degraded spawning habitat in BC rivers, changes in marine habitat resulting from climate change, and decline resulting from by-catch effect in commercial fisheries.

This fish species is high in natural oils, and has been used in grease production. Historically, the eulachon has been part of the First Nations diet. This species has been harvested commercially from the Fraser River since the 1870's, but commercial fishery in BC was closed in 1997 (Fisheries and Oceans Canada 2008).

Species Information

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

Source: FishBase. Eschmeyer, W.N., E.S. Herald and H. Hammann 1983 A field guide to Pacific coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 336 p.

Biology

Species 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)

Source: FishBase. Eschmeyer, W.N., E.S. Herald and H. Hammann 1983 A field guide to Pacific coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 336 p.

Distribution

BC Distribution and Notes

Spawning runs of eulachon are known from most major rivers along the B.C. coast. This fish is especially significant to the coastal first nations and appears to be in serious decline in the Fraser River.

Source: Information provided by Don McPhail for E-Fauna BC.
Global 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).

Source: FishBase. Eschmeyer, W.N., E.S. Herald and H. Hammann 1983 A field guide to Pacific coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 336 p.
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Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
NativeS2S3BlueE/T (May 2011)



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