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.

These data were produced from young-of-the-year brook trout samples, collected from lakes in the Canadian Rocky Mountains. These lakes were either subject to size-selective harvest at a rate of ~0.59, or were left as controls (no harvest). Young-of-the-year brook trout were sampled via electrofishing, a fin clip was collected, and they were released. DNA from the tissues was extracted using a modified Chelex protocol, was amplified, and then sequenced using an Illumina Miseq Sequencer. The genotypes were then demultiplexed and manually scored using MEGASAT software. See Clarke et al. (2022) for further details on the molecular protocol and experimental design.

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