Rocky Mountain Brook Trout harvest project genotypes

Sustainable management of exploited populations benefits from integrating
demographic and genetic considerations into assessments, as both play a
role in determining harvest yields and population persistence. This is
especially important in populations subject to size-selective harvest,
because size selective harvesting has the potential to result in
significant demographic, life-history, and genetic changes. We
investigated harvest-induced changes in the effective number of breeders (
) for introduced brook trout populations (Salvelinus fontinalis) in alpine
lakes from western Canada. Three populations were subject to three years
of size-selective harvesting, while three control populations experienced
no harvest. The  decreased consistently across all harvested
populations (on average 60.8%) but fluctuated in control populations.
There were no consistent changes in  between control or harvest
populations, but one harvest population experienced a decrease in
 of 63.2%. The /  ratio increased consistently across
harvest lakes; however we found no evidence of genetic compensation (where
variance in reproductive success decreases at lower abundance) based on
changes in family evenness ( ) and the number of full-sibling families (
). We found no relationship between  and  or between /
 and  . We posit that change in  was buffered
by constraints on breeding habitat prior to harvest, such that the same
number of breeding sites were occupied before and after harvest. These
results suggest that effective size in harvested populations may be
resilient to considerable changes in Nc in the short-term, but it is still
important to monitor exploited populations to assess the risk of
inbreeding and ensure their long-term survival.