Cooperative Fish and Wildlife Research Units Program: Idaho
Education, Research and Technical Assistance for Managing Our Natural Resources

Managing recreational fisheries requires information on the ecology of the fish species being harvested, their habitats, and on anglers who use the resource. Much like obtaining information on fish and habitat, acquiring useful information from the recreational creel is dependent on both the sampling framework and ability to obtain accurate data. Anadromous Chinook salmon and steelhead provide some of Idaho’s most socially- and economically-important fisheries. Because these species receive federal protection under the Endangered Species Act (ESA), fisheries for hatchery fishes are closely managed to minimize negative impacts on wild stocks. The maximum number of wild fish that can be encountered (i.e., caught and released) is limited with an abundance-based, sliding scale based on predicted returns of wild adults. Estimating the effects of the fishery on wild fish is dependent on the number of fish caught, proportion of wild to hatchery fish caught by anglers, and hooking mortality (assumed to be 10%). As such, major sources of uncertainty are the origin of fishes (i.e., hatchery versus wild) and estimated number of fish caught by anglers, which are directly dependent on the design of the creel survey and the accuracy of angler reporting. A particular concern associated with angler reporting is social desirability bias (SDB). Social desirability bias occurs when a respondent answers (i.e., reports catch) in a way that is perceived to be most socially desirable, not necessarily the most accurate. Although SDB is recognized as a major source of error in the social sciences and their sub-disciplines (e.g., marketing), SDB has been virtually ignored in fishery and wildlife sciences. The overall purpose of this project is to evaluate sources of error in angler surveys associated with recreational Chinook salmon and steelhead fisheries in Idaho. Specific objectives are to evaluate the design of creel surveys (i.e., sampling design, proper use of catch estimators) and to evaluate the occurrence and importance of SDB on catch estimates. Results of this project will directly influence management of one of North America’s premier recreational fisheries.