Sierra Nevada Aquatic Research Laboratory

30 Jun, 05 PM - 29 Jun, 05 PM

All of the field research associated with this project is conducted in the John Muir Wilderness, Sierra National Forest. The majority of Sierra Nevada wilderness lakes on U.S. Forest Service lands are currently stocked with trout by the California Department of Fish and Game (CDFG) on a regular basis. The assumption underlying this stocking program is that in the absence of stocking many of these lakes would lose their fish populations because of a lack of suitable spawning habitat. Research we conducted during Summer 2001 on trout populations in lakes of the John Muir Wilderness, however, suggests that natural reproduction is much more common than previously believed and that fish populations in 60-70% of currently stocked lakes would likely sustain themselves in the absence of stocking (Armstrong, unpublished data). This assessment was based on comparisons between the stocking schedule and the age structure of fish in each of 32 lakes in the John Muir Wilderness study area. This study addressed three important questions. These are (1) what proportion of trout populations in currently-stocked lakes of the High Sierra are self-sustaining; (2) to what extent will fish densities and growth rates in these lakes change if fish stocking were halted; and (3) can the aging technique developed by Knapp be used to predict the degree of change expected. Answers to these questions have important implications for future fish stocking management in Sierra Nevada lakes. For example, in a recent reevaluation of their high mountain lake stocking program, the CDFG recently indicated that one of the criteria to be used in determining which lakes to stock would be that “stocking must fulfill a valid fishery management purpose” (CDFG press release; March 9, 2001). Under this criterion, future stocking of lakes that have sufficient natural reproduction to sustain recreational fisheries (i.e., self-sustaining) would likely be precluded. Unfortunately, despite a critical need to objectively categorize lakes as self-sustaining or non-self-sustaining, methods to make such a categorization have not yet been rigorously tested. Here we propose a second year of research on the self-sustainability of trout populations to complete testing of one promising method. If shown to be effective, this method would allow CDFG staff to evaluate trout population self-sustainability using data from their high mountain lake surveys currently being conducted throughout the Sierra Nevada.

Visit #1002 @Sierra Nevada Aquatic Research Laboratory

Approved

Under Project # 863 | Research

Response by Trout Populations to an Experimental Halt to Stocking

research_scientist - University of California, Santa Barbara

Reservation Members(s)

Roland Knapp Jun 30, 2003 - Jun 29, 2004 (366 days)
Roland Knapp Jun 30, 2003 - Jun 29, 2004 (366 days)

Reserve Resources(s) | Create Invoice

Lab 2 2 Jun 30, 2003 - Jun 29, 2004