The Current Magazine Fall 2016 - Page 31

CA Department of Fish & Wildlife to the Rescue

McCloud River trout are arguably one of the most famous fish in the world. In the early 1870’s rainbow trout from the lower McCloud were taken into a newly built hatchery and transplanted all around the world. Rainbow trout are now on every continent and in just about every mountain range and many have some lineage to original McCloud River rainbow.

Technically speaking, there are two different, genetically distinct types of McCloud River rainbow trout. Trout that lived below the Middle Falls of the McCloud River, an impassable fish barrier, are genetically classified as coastal rainbows. For thousands of years they have been subjected to genetic drift from other populations of rainbows in the form of steelhead. Before Shasta and McCloud dams were built in 1945 and 1965, respectively, steelhead from as far south as the Central Valley and as far north as the Columbia River migrated up the McCloud River. These rainbows share a genetic resemblance to all coastal rainbows and steelhead that have access to the ocean throughout California.

The trout from above the impassable Middle Falls of the McCloud River have been genetically isolated for thousands of years and have evolved into their own distinct fish know as McCloud River redband trout. They are thought to be one of the oldest populations of rainbow trout, called the proto rainbow by some fish biologists. Historically, the range for these unique fish was the upper reaches of the McCloud River system and a few small creeks along the east flanks of Mount Shasta, where the fish have remained isolated for centuries.

Following the turn of the century, fish from the lower river and other strains of rainbow trout had been stocked into the upper McCloud for angling opportunities. Those fish spread throughout the upper basin and readily hyrbidized with McCloud River redband trout, diluting the gene pool. Only a few very small isolated populations of fish survived, unaltered by non-native genetics. After genetic testing by UC Davis and others, these small fragmented populations were identified and eventually became listed by the state as threatened due to the sensitivity of their habitat and the densities of these small populations. These small vestiges of native fish have been monitored and protected for a few decades.

Photo by Mike Weir