Identification of Brook, Brown, Rainbow, and Cutthroat Trout Larvae

Abstract

Abstract Cultured metalarvae and mesolarvae of brook trout Salvelinus fontinalis, brown trout Salmo trutta, rainbow trout Salmo gairdneri, and cutthroat trout Salmo clarki were analyzed for distinguishing pigmentation patterns, variation in size and abundance of oil globules in the yolk, and differences in 48 morphometric and meristic characters by comparison of percent standard lengths and multivariate statistical techniques. Rainbow and cutthroat trouts differed from each other only in that the insertion of the dorsal fin and origin of the adipose fin were more posterior in rainbow trout. Brown trout differed from the other species in having longer pectoral fins, an elliptical yolk and unique pigmentation on the lower jaw, caudal fin, and adipose fin. Brook trout differed from the other species by having numerous minute oil globules in the yolk; a distinctively longer adipose fin; prominent pigmentation on the anterior margin of the mandible, caudal fin, and adipose fin; and a greater number of dorsal a...