Thank you to the California Dept. of Fish and Wildlife for the info below.
In 1972 a section of Hat Creek, Shasta County (from PG&E’s Hat Creek Powerhouse #2 to Lake Britton) became one of California’s first designated Wild Trout waters. This section is known as the Hat Creek Wild Trout Area (WTA). California’s Heritage and Wild Trout waters are managed to provide aesthetically pleasing and environmentally productive environments for anglers to have the opportunity and experience to enjoy California’s wild trout.
Designated Heritage and Wild Trout waters have specific management plans that provide the framework to maintain the goals of the Heritage and Wild Trout Program (HWTP). As part of the management of the WTA, understanding the population and population changes over time help fishery managers make decisions on actions to best manage the fishery. In October 2012, HWTP scientists implemented a mark-recapture sampling method to estimate the population of all trout species common to the WTA.
The Hat Creek WTA has been monitored for population trends since the Hat Creek Wild Trout Project (Project) was completed in the late 1960’s. Since the Project’s completion, several fish sampling/monitoring methods have been implemented to estimate the population or provide an index of relative abundance. Of these methods, the mark-recapture method has remained the preferred method to estimate trout populations in Hat Creek.
The 2012 mark-recapture effort was implemented to: 1) generate a current population estimate for rainbow trout (Oncorhynchus mykiss sp.) and brown trout (Salmo trutta) in the upper WTA, 2) compare the population estimates to past estimates for trends over time, and 3) provide a pre-restoration project baseline using trout population estimates for comparison purposes after the Hat Creek California River Parkway Project has been completed.
Hat Creek Upper Wild Trout Population Estimate:
The upper WTA (sections 1 and 2) population estimates for common trout species using the ≥150 mm (approximately 6 inch) TL cutoff included: rainbow trout 2,754 and brown trout 329. Population estimates for common trout species ≥203 mm (8 inch) FL cutoff included: rainbow trout 1,737 and brown trout 287 (Table 2).