FWS Focus


The Bonneville cutthroat trout (Oncorhynchus clarki utah) is a subspecies of Cutthroat trout that once inhabited the Late Pleistocene-aged Lake Bonneville of Utah, eastern Nevada, and Southern Idaho (USA). Since the desiccation of Lake Bonneville into Great Salt Lake which is too salty for any kind of fish life, Bonneville Cutthroats have been isolated in smaller populations in the headwaters of mountain streams and in lakes of the Bonneville Drainage basin. The isolation has resulted in much phenotypic variation among populations. This species is one of 14 recognized subspecies of Cutthroat trout native to the western United States. This fish has sparsely scattered, very distinct round spots over its upper body. They are clothed in subdued colors of silver-gray to charcoal, the upper body having subtle hues of pink on the flanks during spawning. These fish, particularly the Bear Lake strain, often lack the bright crimson jaw slash that, at times, may be yellow. The difference between cutthroat trout and rainbow trout is that cutthroats have basibranchial (hyoid) teeth in their throat between the gill arches and behind the tongue.[1] They also typically have longer heads and jaws than the rainbow and often can be distinguished from the rainbow by their larger spots. Bonneville cutthroat trout primarily eat insects, but large individuals also eat other fish. They spawn near the mouths of streams over gravel substrate in the springtime, having an incubation period of 24 to 25 days.

Scientific Name

Oncorhynchus clarkii utah
Common Name
Bonneville cutthroat trout
FWS Category

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Identification Numbers



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