Hunt Creek Fisheries Research Station
Route #2, Box 2299
Lewiston, Michigan 49756
Abstract.-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. By selection of appropriate brood stocks, fishery managers
could double or quadruple brown trout catch rates for some
catch-and-release fisheries that are established or maintained by
stocking. Conversely, managers could reduce angler exploitation rate,
thus permitting trout to grow for a greater length of time in
harvested fisheries, by stocking strains that are less catchable.