Classification / Names
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL | WoRMS | Cloffa
Actinopterygii (ray-finned fishes) > Salmoniformes
(Salmons) > Salmonidae
(Salmonids) > Coregoninae
Etymology: Prosopium: Greek, prosopon = face (Ref. 45335); williamsoni: Named after Lieut. R. S. Williamson of the U.S. Pacific Railroad Exploration.
Environment: milieu / climate zone / depth range / distribution range
Freshwater; benthopelagic; depth range 5 - 20 m (Ref. 1998), usually 5 - 6 m (Ref. 1998). Temperate; ? - 23°C (Ref. 12741); 68°N - 39°N
North America: Mackenzie River drainage in Northwest Territory, Canada south through western Canada and northwestern USA in the Pacific, Hudson Bay and upper Missouri River basins to Truckee River drainage in Nevada and Sevier River drainage in Utah, USA.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 70.0 cm TL male/unsexed; (Ref. 40637); common length : 23.4 cm TL male/unsexed; (Ref. 12193); max. published weight: 2.9 kg (Ref. 40637); max. reported age: 17 years (Ref. 72462)
soft rays: 10 - 13;
Vertebrae: 53 - 61. Body slender, elongate, nearly cylindrical in cross section but variable, more compressed laterally than round whitefish. Head short; eye moderate, its diameter less than snout length; snout more or less pointed, compressed laterally, pinched, rounded in lateral view, a single flap of skin present between nostrils. Mouth small, ventral in position, overhung by snout; maxillaries extending posteriorly almost to anterior margin of eye in adults. Teeth small, restricted to a small patch on tongue and on gill rakers in adults, although small teeth may be present on the premaxillaries in young, but absent from jaws, vomer, palatines and pre maxillae in adults. Overall coloration silvery, but light or dark brown or olive on back, becoming silvery in sides and white below. Scales, specially on back, may have pigmented borders. dorsal fin often dusky, pelvic and pectoral fins in adults with amber tint.
Occurs in lakes and fast, clear or silty streams. Feeds mainly on benthic organisms such as aquatic insect larvae, mollusks, fishes, and fish eggs (including their own) but may feed on plankton and surface insects when the need arises (Ref. 1998).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
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. 119314)
CITES (Ref. 115941)
Threat to humans
Fisheries: minor commercial; gamefish: yes
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 0.5156 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00501 (0.00406 - 0.00618), b=3.18 (3.12 - 3.24), in cm Total Length, based on LWR estimates for this species (Ref. 93245
Trophic Level (Ref. 69278
): 3.7 ±0.1 se; Based on diet studies.
Resilience (Ref. 69278
): Low, minimum population doubling time 4.5 - 14 years (tmax=14).
Vulnerability (Ref. 59153
): High vulnerability (55 of 100) .