Rainbow Trout

Scientific Name: Oncorhynchus mykiss

Identifying Characteristics: Like all salmonids, rainbow trout have a fleshy adipose fin located between the dorsal fin and caudal fin (tail). Rainbow trout can vary in color but often have a broader distribution of small black spots than most cutthroat. Rainbow trout often have a red or pink band along the midline (side). Rainbows generally lack the red slash marks that cutthroat species have under the jaw line. A faint slash mark has been noted to occur in Columbia River redband rainbow trout, a sub species of rainbow trout. Unlike cutthroat trout (>4” in length), rainbow trout have a maxillary (upper jaw) that does not extend behind the eye. The distinguishing characteristic in rainbow trout is the lack of basibranchial (hyoid) teeth behind the tongue, which are present in cutthroat trout. Due to the potential hybridization between rainbow trout and westslope cutthroat trout, any fish having slash marks and basibranchial teeth behind the tongue should be considered either a hybrid or cutthroat.

Status: Not native to the Pend Oreille Watershed with the exception of anadromous steelhead trout that had historic runs near the Salmo River in Canada. Although not native to the Pend Oreille, rainbow trout are native in eastern Washington, including the Spokane River drainage south of WRIA 62.

Distribution: Rainbow trout (RBT) have been legally stocked in many locations within the Pend Oreille watershed. RBT can be found in Lake Pend Oreille, the Pend Oreille River and many local lakes and tributaries both connected and disconnected from the main Pend Oreille River system.

Species Notes: Rainbow trout are problematic to westslope cutthroat trout due to competition for space and resources, predation risk, and their ability to hybridize with cutthroat. Currently, there is a bounty for rainbow trout in Lake Pend Oreille.