Exploitation and catch and release of salmonids in Idaho high mountain lakes

Abstract Objective Historically, most high mountain lakes in western North America were devoid of fish, but during the past century, many have been stocked with salmonids to diversify angling opportunities. Basic information on harvest and catch and release (C–R) for high mountain lake fisheries is lacking, as is information on factors influencing catch in such settings; our objectives were to fill these knowledge gaps. Methods Using angling gear, we captured and implanted T-bar anchor tags into 1163 salmonids of various species (fish of wild origin or hatchery fish stocked as fry; they could not be distinguished) in 103 high mountain lakes scattered across Idaho. Angler-reported tag returns were used to estimate annual rates of exploitation and C–R, and a model selection approach was used to investigate factors influencing the angler catch of tagged fish. Result Anglers reported the catch of 125 tagged fish from 52 different lakes. The mean number of days at large for reported fish was 318 days, with a range of 1 to 1465 days. Annual exploitation was 5.8 ± 7.1% (mean ± 90% confidence interval), the annual C–R rate was 8.5 ± 8.5%, and total annual catch (i.e., exploitation plus C–R) was 14.2 ± 11.0%. Of the predictive factors that we investigated, the likelihood of a fish being caught by an angler was negatively associated with hiking distance and positively associated with shoreline development index and fish length. Conclusion Our results indicate that exploitation of salmonids in Idaho high mountain lakes is low even with liberal (six-fish daily bag limit) harvest regulations. Consequently, angler harvest is unlikely to be substantively affecting the abundance or size structure of salmonid populations in these lakes. Continued tagging would improve the precision of exploitation and C–R estimates, especially for comparisons among species.