Environment: milieu / climate zone / depth range / distribution range
Marine; freshwater; brackish; demersal; catadromous (Ref. 51243). Temperate; 68°N - 35°N, 175°W - 120°W
North America: Bristol Bay and Aleutian Islands, Alaska to northern California, USA. Isolated populations in lower Kobuk River (Alaska), Cultus Lake (British Columbia, Canada), and Lake Washington (USA) (Ref. 27547).
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 17.0 cm TL male/unsexed; (Ref. 5723); common length : 6.0 cm TL male/unsexed; (Ref. 12193); max. reported age: 8 years (Ref. 27547)
(total): 8 - 10;
soft rays: 12 - 15;
Vertebrae: 34 - 38. Distinguished by having only a single pore on the tip of the chin, no palatine teeth and no pronounced gap between 1st and 2nd dorsal fins (Ref. 27547). Dark brown to greenish or grayish on back and sides, with darker blotches; sides lighter, ventral areas white; usually two or three dark saddle-like blotches below soft part of dorsal fin; dark bars on dorsal, anal, pectoral and caudal fins; orange edge on spiny dorsal fin of spawning males (Ref. 27547).
Inhabits gravel and rubble riffles of medium to large rivers and rocky shores of lakes (Ref. 5723). Occasionally enters estuaries (Ref. 5723) and nearshore coastal water (Ref. 43939). Feeds mostly at night and mostly on aquatic insects and benthic invertebrates (Ref. 27547). Generally solitary but large aggregations have been noted (Ref. 27547). Makes regular seasonal migrations associated with spawning (Ref. 27547). Considered a forage fish for some salmonids (Ref. 1998).
Adults make regular seasonal migrations associated with spawning. They move downstream to estuaries or at least to lower reaches of rivers in the spring, mostly at night (Ref. 27547). Eggs are deposited on the undersurface of a rock, in adhesive masses (Ref. 1998). Over 7,000 eggs have been found in a single nest, suggesting that a male may spawn with several females (Ref. 1998, 27547). The male guards the nest until all eggs have hatched (Ref. 1998, 27547). A reverse, upstream migration of yearlings and adults occur in late summer to early winter, from August to December (Ref. 27547).
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. 126983)
Threat to humans
Fisheries: of no interest
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82804
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00676 (0.00300 - 0.01523), b=3.17 (2.98 - 3.36), in cm total length, based on LWR estimates for this (Sub)family-body shape (Ref. 93245
Trophic level (Ref. 69278
): 3.2 ±0.3 se; based on diet studies.
Resilience (Ref. 120179
): Medium, minimum population doubling time 1.4 - 4.4 years (tm=3; tmax=8; Fec=100).
Fishing Vulnerability (Ref. 59153
): Low vulnerability (10 of 100).