Coho Salmon (Oncorhynchus kisutch)

Identification:

Juveniles: Parr marks oval and narrower than interspace. Long first rays of dorsal and anal fins often white, anal fin sickle-shaped. Adipose fin uniformly spotted. No spots on dorsal fin, some on upper lobe of caudal fin.

Adults: Metallic blue on the dorsal surface, silvery on sides and ventral surface. Round black spots on the back and the upper lobe of the caudal fin. Gums at base of teeth in lower jaw are white. Length usually 18 to 24 inches.

Spawning adults: Males develop a brilliant red stripe on the sides, bright green on the back and head, and are often dark on the belly. The upper jaw develops into an elongate hooked snout. Females are usually bronze to pinkish red on the sides.

Life History: All anadromous. Sexually maturing adults return to natal streams during the late summer and autumn. The spawning season is generally from November to January, but spawning can occur as early as September or as late as mid-MR.h. The female selects the redd site, generally in an area of shallower, swifter water over gravel. She digs the nest and lays her eggs which are simultaneously fertilized by the male. Fecundity is greatly variable with the region and the size of the fish, average number in British Columbia ranges from 2100 to 2789 eggs per female. Both females and males die after spawning is completed. The eggs incubate below the gravel during the winter, and the fry hatch and emerge in the spring. The fry then stay in the stream for twelve to fifteen months, after which they migrate out to sea. The adults live in the ocean for sixteen to eighteen months at which point they return to their natal stream to spawn.

Feeding: The juvenile fish feed mainly on insect larvae, insects, oligochaetes and arachnids, also small chum and pink salmon. Ocean fry feed on pink and chum fry, other fishes, squid and crustaceans. Marine adults prey on fish and invertebrates such as squid, barnacles and jellyfish.

References:

 

Groot, C and Margolis, L. Eds. 1991. Pacific Salmon Life Histories. UBC Press. Vancouver, B.C.

Juvenile fish id key. 1995. The Streamkeepers Handbook: a Practical Guide to Stream and Wetland Care. Community Involvement Division, Salmonid Enhancement Program, Department of Fisheries and Oceans. Vancouver, B.C.

Scott, W and Crossman, E. 1973. Freshwater Fishes of Canada. Fisheries Research Board of Canada. Bulletin 184. Ottawa, Ontario.

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