Oncorhynchus gorbuscha

Author: (Walbaum, 1792)

Oncorhynchus gorbuscha (Walbaum, 1792)

Status in World Register of Marine Species:
Accepted name: Oncorhynchus gorbuscha (Walbaum, 1792) (updated 2009-06-25)

Diagnosis: elongate, becoming deeper with age, spawning males developing a hump on back before dorsal fin. Tip of upper jaw reaching well behind eye; snout and lower jaw becoming strongly hooked in spawning males. Gillrakers 26-32. Pyloric caeca 120-140. Dorsal finrays iii-iv 9-12, and an adipose fin behind it; pelvic finrays i 9-10, base below about middle of dorsal fin; anal finrays ii-iv 12-16; caudal fin slightly forked. Scales very small, 143-207 in lateral line. Vertebrae 69-72. Colour: silvery, almost without dark spots, but during spawning developing blotches on head, upper flanks and caudal fin, the colour almost black. Size: to 64 cm and 3.2 kg, usually 40-50 cm (spawning adults).

Habitat: pelagic at O-50 m, but deeper in winter, forming dense shoals during spawning run and making considerable migrations; juveniles in estuarine areas for several months before migration to sea. Food: crustaceans (harpacticoids, calanids, amphipods) by juveniles in estuaries of White and Barents Seas; small fishes, squids, euphausiids, amphipods and copepods recorded in Pacific populations; in freshwaters adults do not feed. Reproduction: August-September (a few in Octoberj at 2 years old, very rarely 3 (mid-July to late September in Pacific); adults die after spawning; juveniles leave rivers June-July or later (late spring to early summer in Pacific), spending one year at sea.

Distribution: a Pacific fish introduced into rivers affluent to White and Barents Seas (I956-63, 1967-75). now more widespread, the stocks maintained by both natural spawning and further stocking; well established in rivers from Ob to Finmark, but straying further south; records from southern Norway and south-eastern Sweden may have been strays from stocking in Bay of Riga (Berg, 1977).

Eggs, larvae and young stages. Soldatov, 1912: 108, pl. A (fig. 1-6) (col.) | Soin, 1956: 1364, fig. 1 (3), 2 (3).
Otoliths (sagitta). No data.