Can Fin-clips Identify Different Trout Strains?

April 24, 2014

Question: With trout season opening soon, I was thinking about how several years ago I ran across a way to identify what strain a Lake Crowley trout was based on which fins were clipped. Identify as follows: adipose only-Eagle Lake strain, adipose and left ventral-Kamloops (from Junction Reservoir), adipose and right ventral-Coleman, and ventral only-Kamloops or Coleman. No fin clips would indicate a natural spawn and not from a hatchery. And, what hatchery would these plants have come from? Possibly Hot Creek or maybe Fish Springs? I have talked to the driver planting catchables in Silver Lake and learned those plants came from the Fish Springs hatchery. Thanks for any info you can provide. (Ron A.)

Answers: In the mid-1990s, California Department of Fish and Wildlife (CDFW) fisheries biologists applied fin clips to Eastern Sierra trout stocked in Crowley Lake to evaluate their performance, growth, return to creel, etc. The results were very interesting.

According to CDFW Fisheries Program Manager Curtis Milliron who conducted those studies, wild trout were unmarked and at that time both rainbow trout (RT) and browns constituted about 25 percent of the catch of all larger fish caught at Crowley. They did not substantially supplement the average size class, however. The marked trout came from both Fish Springs (Coleman strain RT and Eagle Lake trout) and from Hot Creek Hatchery (Kamloops strain RT).

Coleman strain fish were found to be caught most often by anglers while trolling, while Kamloops were often associated with nearshore angling. Eagle Lake trout (ELT) were found all over the lake, including feeding on large snails right on the lake bottom. Additionally, ELT outlived the other strains, and therefore greatly contributed to the “carryover” population, which are fish that do not get caught in the first year after being stocked and return to anglers at a much larger size.

By about 1999, Milliron discontinued the Crowley Lake trout strain studies but thinks some marked fish may have persisted in the lake for another five years, at most. Today, no similar studies are being conducted, and fin clips to identify the various strains of Eastern Sierra trout are no longer being applied. But, thanks to the findings of the studies, a management plan for Lake Crowley was created, and the lake continues to draw anglers back year after year as one of the most popular and productive trout lakes in the Eastern Sierra.