Yellowfin Cutthroat Trout
Oncorhynchus clarkii macdonaldi
The yellowfin cutthroat trout (Oncorhynchus clarkii macdonaldi) is an extinct subspecies or variety of the cutthroat trout, a North American freshwater fish. Until about 1903, greenback and yellowfin cutthroats survived together in Twin Lakes, the populations remaining isolated as both breeders and feeders. The end for the yellowfin cutthroat came soon after the introduction of the rainbow trout to Twin Lakes. The greenback population interbred with the rainbows, resulting in cutbows, but the yellowfin disappeared completely. The yellowfin is now extinct.