Past habitat degradation caused by sheep and cattle grazing was a significant threat to the PCT. Cattle grazing was ceased by the U.S. Forest Service (USFS) in 1994. To protect this subspecies and its habitat, grazing is no longer allowed in the upper Silver King Creek basin above Snodgrass Creek.
The introduction of non-native trout into their historic range was a major cause of the PCT’s decline. Five different trout species have been moved into and around the Silver King drainage, including PCT, Lahontan Cutthroat Trout, California Golden Trout, Rainbow Trout, and Brook Trout. PCT were extirpated from their historical habitat due to introduced trout but exist in formerly fishless areas of the Silver King Creek drainage and four out-of-basin watersheds above fish passage barriers.
PCT is one of the most imperiled native fish in California, due to loss of genetic diversity and habitat fragmentation. Evidence of genetic diversity loss has been found in all PCT populations. They are all completely isolated from each other, so there can be no genetic exchange or recolonization after a catastrophic event, such as a large forest fire. Current populations are small, and isolated by waterfalls which are barriers to fish migration. This puts them at risk of hybridization with non-native trout and exposes them to the harmful effects of wildfires, drought, and climate change. In short sections of streams (called “reaches”), both the population size and habitat diversity may be inadequate for the species to survive, long-term.
Historically, recreational fishing was a threat to PCT. Because small streams are vulnerable to overharvest, recreational fishing for PCT has been closed in the Silver King Creek drainage since 1934.