Abstract
Supplementation stocking is a commonly used management tool to sustain exploited fish populations. Possible negative consequences of supplementation on local stocks are a concern for the conservation of wild fish populations. However, the direct impacts of supplementation on life history traits of local populations have rarely been investigated. In addition, intraspecific hybridization between contrasting ecotypes (planktivorous and piscivorous) has been seldom considered in supplementation plans. Here, we combined genetic (genotype-by-sequencing analysis) and life history traits to document the effects of supplementation on maximum length, growth rates, body condition and genetic admixture in stocked populations of two Lake Trout ecotypes from small boreal lakes in Quebec and Ontario, Canada. In both ecotypes, the length of stocked individuals was greater than local individuals and, in planktivorous-stocked populations, most stocked fish exhibited a planktivorous-like growth while 20% of fish exhibited piscivorous-like growth. The body condition index was positively related to the proportion of local genetic background, but this pattern was only observed in stocked planktivorous populations. We conclude that interactions and hybridization between contrasting ecotypes is a risk that could result in deleterious impacts and possible outbreeding depression. We discuss the implications of these findings for supplementation stocking.
Highlights
The voluntary introduction of exogenous animals and plants is one of the most frequent anthropogenic perturbations of wild populations [1]
We modeled the effects of genetic background on individual Lake Trout growth parameters (Linf, ω) and the condition index (Wr) for each stocked population
We retained an average of 600 single-nucleotide polymorphisms (SNPs) markers for pairwise comparisons between the source and stocked populations
Summary
The voluntary introduction of exogenous animals and plants is one of the most frequent anthropogenic perturbations of wild populations [1]. Deliberate releases of exogenous fish commonly have the goal of increasing the abundance of a threatened population, increasing potential fish harvest or introducing new species [2]. The stocking of lakes with fish reared in hatcheries has been an important management approach, both in North America. Lake Trout ecotypes importance in supplementation stocking exploitees to PS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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