Comparative Catchability, Growth, and Survival of Two Wild Stocks of Brown Trout

摘要

The catchability and genetic growth potential of trout may be changed, over time,by differential angler harvest of more catchable and faster-growing fish from each cohort. To test this hypothesis, yearling brown trout Salmo trutta from the Au Sable River and Gilchrist Creek were stocked into Fuller Pond. Brown trout populations from the Au Sable River were believed to have been historically exploited more intensively than those in Gilchrist Creek. We compared their vulnerability to capture by angling, relative growth, and survival over a 2.5 year period. Using artificial flies and lures, Gilchrist fish were approximately four times easier to catch at age 2, and three times easier to catch at age 3 than Au Sable fish. Vulnerability to angling was not correlated with growth rates, as few significant differences occurred in growth. There was also no difference in survival of the two strains during the study period. Differential angler exploitation over time may have altered catchability of these wild trout stocks. Other factors that could account for observed differences in catchability include genetic dissimilarity of founder stocks, genetic differences due to differences in natural selection between the rivers, or unknown factors.