Actinopterygii (ray-finned fishes) > Salmoniformes
(Salmons) > Salmonidae
(Salmonids) > Salmoninae
Etymology: Oncorhynchus: Greek, onyx, -ychos = nail + Greek, rhyngchos = snout (Ref. 45335); gorbuscha: gorbuscha which is the Russian name for this fish in Alaska (Ref. 1998).
Environment / Climate / Range
Marine; freshwater; brackish; demersal; anadromous (Ref. 51243); depth range 0 - 250 m (Ref. 50550). Subtropical; ? - 21°C (Ref. 12741); 79°N - 29°N, 5°E - 114°W (Ref. 54683)
Length at first maturity / Size / Weight / Age
Maturity: Lm 45.0, range 40 - 50 cm
Max length : 76.0 cm TL male/unsexed; (Ref. 9015); common length : 50.5 cm TL male/unsexed; (Ref. 12193); max. published weight: 6.8 kg (Ref. 27436); max. reported age: 3 years (Ref. 27547)
soft rays: 11 - 19;
Vertebrae: 63 - 72. Distinguished by the presence of large black spots on the back and on both lobes of the caudal fin; the young have no parr marks (Ref. 27547). Body fusiform, streamlined, somewhat laterally compressed; moderately, deeper in breeding males (Ref. 1998). Mouth terminal, normally very little oblique but greatly deformed in breeding males, with lower jaw enlarged, turned up at tip, mouth unable to close (Ref. 1998). Adipose fin large; pelvic fins with axillary process (Ref. 27547). Fish in the sea are steel blue to blue-green on the back, silver on the sides and white on the belly; large oval spots present on the back, adipose fin and both lobes of the caudal fin (Ref. 27547). Breeding males become dark on the back, red with brownish green blotches on the sides; breeding females are similar but less distinctly colored (Ref. 27547). Differs from Oncorhynchus mykiss by having the following unique characters: anal fin with 11-15½ (usually 13½ ) branched rays; 177-240 scales in midlateral row; 26-33 gill rakers; large mature males with enormous hump; juveniles lacking parr marks; and lacking pink to red stripe on flank (Ref. 59043).
Arctic and Pacific drainages from Mackenzie River delta, Northwest Territories, Canada to Sacramento River drainage, in California, USA; occasionally as far as La Jolla, southern California; also in northeast Asia (Ref. 5723). On Asia side, from North Korea to Jana and Lena drainages in Artic Russia. In Bering Sea north of about 40°N and from Bering Strait northeast to Point Barrow and northwest to Lena estuary (Ref. 59043). Introduced elsewhere. Occasionally hybridizes with Oncorhynchus keta producing fertile offspring (Ref. 28983).
An anadromous species which inhabits ocean and coastal streams (Ref. 5723). Epipelagic (Ref. 58426). Pelagic at the sea. In freshwater, lives in montane and piedmont rivers with moderate to fast current and gravel bottom. Spawns in riffles or at head of riffles in shallow water with current up to 1.5 m/s, and clean coarse gravel (Ref. 59043). Spends 18 months at sea after which spawning migration to the natal river or stream occurs; but because the species is less certain of its homing and there is a certain degree of wandering, streams as much as 640 km from natal streams may be used (Ref. 1998, 27547). Upon emerging from the gravel, fry immediately move downstream and remain inshore for a few months before going out to sea. Fry may feed on nymphal and larval insects while in fresh water, but may not feed at all. In the sea, young feed on copepods and larvacean tunicates, its diet shifting to amphipods, euphausiids and fishes as the fish grows (Ref. 27547). Other food include ostracods, decapod larvae, cirripeds, tunicates, dipterous insects (Ref. 1998, 27547). Fry may be preyed upon by birds and mammals while adults by marine mammals and large fish (Ref. 1998). Mostly sold canned (Ref. 1998) but also utilized fresh, smoked, and frozen; also valued for caviar, especially in Japan; eaten steamed, fried, broiled, boiled, microwaved, and baked (Ref. 9988). The smallest of the true salmon (Ref. 12218). The Alaska Salmon fishery of this species has been certified by the Marine Stewardship Council (http://www.msc.org/) as well-managed and sustainable (http://www.msc.org/html/content_485.htm).
Adults develop secondary sexual characteristics during their upstream migration (Ref. 1998), which occurs any time from June to late September, depending on location (Ref. 27547). Male develop a humpback, an enlarged head and large teeth on both jaws that form a pronounced hooked type (Ref. 59043). The upstream run seems to be triggered by high water (Ref. 27547). Female builds the redd by lying on one side and using its tail, it displaces silt and light gravel to produce a deep trough. Male spends most of the time driving off intruding males. When the redd is completed, the female drops into it, followed immediately by the male. They open their mouths, vibrate and release eggs and sperm. In some cases, several males spawn with a single female. The eggs are then covered as the female digs a new redd at the upstream edge of the previous one. Adults live up to a few weeks after spawning before they die (Ref. 1998, 27547). Reported to die 10-20 days after spawning (Ref. 59043). About 1200-1800 eggs are laid. After hatching and the yellow egg yolk is absorbed, if the hatchling doesn't have a parr mark they go to the ocean and come again to the same birthplace stream the next year during spring after growing for 16-18 months. Survival rates are low, at 1-25% (taken from a Canadian river) (Ref. 12218). Reproductive strategy: synchronous ovarian organization, determinate fecundity (Ref. 51846).
Page, L.M. and B.M. Burr, 1991. A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p. (Ref. 5723)
IUCN Red List Status (Ref. 96402)
CITES (Ref. 94142)
Threat to humans
Fisheries: highly commercial; aquaculture: commercial; gamefish: yes
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.01175 (0.00648 - 0.02132), b=3.08 (2.93 - 3.23), based on LWR estimates for this species & Genus-body shape (Ref. 93245
Trophic Level (Ref. 69278
): 4.5 ±0.4 se; Based on diet studies.
Resilience (Ref. 69278
): Medium, minimum population doubling time 1.4 - 4.4 years (tm=2; tmax=3; Fec=800).
Vulnerability (Ref. 59153
): Moderate vulnerability (37 of 100) .