Oncorhynchus mykiss (Walbaum, 1792)
Rainbow trout
Oncorhynchus mykiss
photo by McDowall, R.M.

Family:  Salmonidae (Salmonids), subfamily: Salmoninae
Max. size:  122 cm TL (male/unsexed); max.weight: 25 kg; max. reported age: 11 years
Environment:  benthopelagic; depth range 0 - 200 m, anadromous
Distribution:  Native to Pacific Slope from Kuskokwim River, Alaska to (at least) Rio Santa Domingo, Baja California, Mexico; upper Mackenzie River drainage (Arctic basin), Alberta and British Columbia in Canada; endorheic basins of southern Oregon, USA. Widely introduced in cold waters elsewhere in North America and rest of the world (Ref. 5723). Eastern Pacific: Kamchatkan Peninsula and have been recorded from the Commander Islands east of Kamchatka and sporadically in the Sea of Okhotsk as far south as the mouth of the Amur River along the mainland. The records outside Kamchatka probably represent migrating or straying Kamchatkan steelhead (penshinensis) rather than the established native population (Reg. 50080). Several countries report adverse ecological impact after introduction.
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 10-12; Anal spines: 0-0; Anal soft rays: 8-12; Vertebrae: 60-66. Body elongate, somewhat compressed especially in larger fish. No nuptial tubercles but minor changes to head, mouth and color occur especially in spawning males. Coloration varies with habitat, size, and sexual condition. Stream residents and spawners darker, colors more intense. Lake residents lighter, brighter, and more silvery. Caudal fin with 19 rays (Ref. 2196). Differs from Oncorhynchus gorbuscha by having the following unique characters: by having the following unique characters: anal fin with 6-9½ (usually 8½ ) branched rays; 115-130 scales in midlateral row; 16-17 gill rakers; breeding males lacking hump; juveniles lacking parr marks; wide pink to red stripe from head to caudal base, except in sea-run form; and juveniles with 5-10 parr marks (Ref. 59043).
Biology:  Adults inhabit cold headwaters, creeks, small to large rivers, and lakes. Anadromous in coastal streams (Ref. 5723). Stocked in almost all water bodies as lakes, rivers and streams, usually not stocked in water reaching summer temperatures above 25°C or ponds with very low oxygen concentrations. Feed on a variety of aquatic and terrestrial invertebrates and small fishes. At the sea, they prey on fish and cephalopods. Mature individuals undertake short spawning migrations. Anadromous and lake forms may migrate long distances to spawning streams (Ref. 59043). Utilized fresh, smoked, canned, and frozen; eaten steamed, fried, broiled, boiled, microwaved and baked (Ref. 9988). Cultured in many countries and is often hatched and stocked into rivers and lakes especially to attract recreational fishers (Ref. 9988).
IUCN Red List Status: Not Evaluated (Ref. 115185)
Threat to humans:  potential pest
Country info:   
 

Entered by: Luna, Susan M. - 17.10.90
Modified by: Valdestamon, Roxanne Rei - 16.12.14
Checked by: Casal, Christine Marie V. - 15.01.03

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