A trout with small, nonrounded spots, with few spots on the anterior body below the lateral line; coloration varies, but generally is silver with yellowish hints, though bright yellow, orange, and especially red colors can be expressed to a much greater extent than on coastal or Yellowstone cutthroat (Behnke 1992). Hybridization between westslope and Yellowstone cutthroat trout can produce a spectrum of spotting and coloration ranging between the typical patterns of each subspecies. Some populations that have been affected by hybridization show little or no phenotypic signs of hybridization (Behnke 1992). Hybridization with rainbow trout can be detected by the appearance of spots on the top of the head and on the anterior body below the lateral line, as well as by reduced scale counts, increased caecal counts, and loss of basibranchial teeth (see Behnke 1992).
Animalia - Craniata - Actinopterygii - Salmoniformes - Salmonidae - Oncorhynchus - (Yellowstone), which exhibit substantial genetic divergence.
Ecology and Life History
A trout with small, nonrounded spots, with few spots on the anterior body below the lateral line; coloration varies, but generally is silver with yellowish hints, though bright yellow, orange, and especially red colors can be expressed to a much greater extent than on coastal or Yellowstone cutthroat (Behnke 1992). Hybridization between westslope and Yellowstone cutthroat trout can produce a spectrum of spotting and coloration ranging between the typical patterns of each subspecies. Some populations that have been affected by hybridization show little or no phenotypic signs of hybridization (Behnke 1992). Hybridization with rainbow trout can be detected by the appearance of spots on the top of the head and on the anterior body below the lateral line, as well as by reduced scale counts, increased caecal counts, and loss of basibranchial teeth (see Behnke 1992).
Short General Description
A cutthroat trout.
Habitat Type Description
Freshwater
Migration
true - true - false - In the Blackfoot River drainage (Montana), 16 of 22 radio-tagged individuals migrated during the spawning period; migrations to tributaries occurred during the rising limb of the hydrograph; migratory fishes moved both upriver and downriver to reach spawning tributaries; in one year the mean distance traveled to access tributaries was 31 km (range 3-72 km); once in tributaries, individuals generally remained within a 200-m reach; neither of two repeat migrants spawned within 3 km of the previous year's spawning location, though both traveled in the same tributaries; after leaving tributaries fishes moved both upriver and downriver to overwintering areas and did not move more than 100 m thereafter; individuals did not exhibit fidelity to their prespawning main-stem locations; in general, fishes demonstarted the large spatial extent over which fluvial westslope cutthroat trout use aquatic resources (Schmetterling 2001).
Non-migrant
true
Locally Migrant
true
Food Comments
Feeds mainly on aquatic and terrestrial insects and zooplankton; diet includes relatively few fishes (Spahr et al. 1991, McIntyre and Rieman 1995).
Reproduction Comments
Spawns March-July, depending on elevation, at water temperatures near 10 C; usually first spawns at age 4 or 5; alternate-year spawning has been reported in the Flathead River basin in Montana and elsewhere; repeat spawners may comprise up to about 24% of the adult population (Spahr et al. 1991, McIntyre and Rieman 1995).<br><br>In the Blackfoot River drainage, Montana, fishes spawned as flows subsided after the peak discharge; 38% of individuals died after spawning (Schmetterling 2001).
Ecology Comments
Metapopulation theory may apply to this species (see McIntyre and Rieman 1995).
Conservation Status
NatureServe Global Status Rank
G4T3
Global Status Last Reviewed
2003-01-31
Global Status Last Changed
1999-10-25
Other Status
T,SC
Distribution
Conservation Status Map
<img src="http://www.natureserve.org/explorer/servlet/GetMapGif?CA.AB=S2&CA.BC=S3&US.CO=SE&US.ID=S3&US.MT=S2&US.OR=S3&US.WA=SNR&US.WY=S1" alt="Conservation Status Map" style="width: 475px; height: auto;" />
Global Range
G - 200,000-2,500,000 square km (about 80,000-1,000,000 square miles) - G - West of the Continental Divide, this subspecies is believed to be native to several major drainages of the Columbia River basin, including the upper Kootenai River drainage from its headwaters in British Columbia, through northwest Montana, and into northern Idaho; the Clark Fork River drainage of Montana and Idaho downstream to the falls on the Pend Oreille River near the Washington-British Columbia border; the Spokane River above Spokane Falls and into Idaho's Coeur d'Alene and St. Joe River drainages; and the Salmon and Clearwater River drainages of Idaho's Snake River basin (USFWS 2003). The native distribution also includes disjunct areas draining the east slope of the Cascade Mountains in Washington (Methow River and Lake Chelan drainages, and perhaps the Wenatchee and Entiat river drainages), the John Day River drainage in northeastern Oregon, and the headwaters of the Kootenai River and several other disjunct regions in British Columbia (USFWS 2003). East of the Continental Divide, the native distribution is believed to include the headwaters of the South Saskatchewan River drainage (United States and Canada); the entire Missouri River drainage upstream from Fort Benton, Montana, and extending into northwest Wyoming; and the headwaters of the Judith, Milk, and Marias rivers, which join the Missouri River downstream from Fort Benton (USFWS 2003).<br><br>Behnke (1992) regarded the mountain cutthroat trout of British Columbia (nominal subspecies <i>alpestris</i>) as disjunct populations of <i>O. clarkii leweisi</i>.
Global Range Code
G
Global Range Description
200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
