Effects of Recreational Fishing on the Population Dynamics of Lake-Dwelling Brook Trout

Abstract

Data collected over 7 consecutive years were used to examine the population dynamics of the exploited brook trout Salvelinus fontinalis of Meach Lake in central Ontario. Numbers of age-1 and older trout averaged 975 among years. The largest trout were 490 mm long and weighed 1,807 g. Few trout lived beyond age 4. Annual mortality rates varied among age-classes and between sexes; average total instantaneous mortality was 0.95 and average total and fishing mortalities were 78% and 44%, respectively. Exploitation was greatest for age-2 and age-3 brook trout of both sexes. Catchability was uncorrelated with abundance. There was evidence of density-dependent growth at age-2 or age-3 but no indication of density-dependent mortality. A “hockey stick” model appeared to best describe the stock–recruitment relationship. Abundance of potential competitors was not correlated with brook trout size, although abundance of white suckers Catostomus commersoni was correlated with numbers of age-2 male brook trout. We conclude that total mortality rates are naturally very high and existing levels of harvests in this lake may not be increasing total mortality. To ensure the sustainability of brook trout fisheries, lake-dwelling populations should be managed to maintain total mortality rates below those observed in this study.