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Supplementary stocking selects for domesticated genotypes.
Ingerid J Hagen1, Arne J Jensen2, Geir H Bolstad2
1Norwegian Institute for Nature Research (NINA), P.O. Box 5685 Torgarden, 7485, Trondheim, Norway. ingerid.arnesen@nina.no.
Nature Communications
|January 16, 2019
Summary
Hatchery stocking of Atlantic salmon unintentionally favors farmed fish genes. This genetic introgression compromises the fitness of wild populations, highlighting unintended consequences of fish stocking practices.
Area of Science:
- Aquatic Ecology
- Conservation Genetics
- Fisheries Management
Background:
- Fish stocking is a common conservation strategy for declining wild populations.
- Hatchery broodstock may possess farmed genotypes, leading to genetic introgression.
- Unintended genetic consequences of stocking can impact wild populations.
Purpose of the Study:
- To investigate the impact of stocking on genetic introgression in wild Atlantic salmon (Salmo salar).
- To quantify the relationship between parental introgression and offspring success in a stocked river.
Main Methods:
- Quantified adult offspring recaptures in a stocked river.
- Assessed parental introgression levels in broodstock.
- Compared reproductive success of introgressed versus non-introgressed broodstock.
Main Results:
- Hatchery conditions favored farmed genotypes.
- Introgressed broodstock produced up to four times more adult offspring than non-introgressed broodstock.
- Stocking led to increased introgression in the recipient wild population.
Conclusions:
- Stocking can unintentionally favor introgressed individuals.
- Selection for domesticated genotypes compromises the fitness of stocked wild populations.
- This study provides the first empirical evidence of this phenomenon in Atlantic salmon.
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