Journal Article

Genetic and ecological effects of salmon farming on wild salmon: modelling from experimental results

Kjetil Hindar, Ian A. Fleming, Philip McGinnity and Ola Diserud

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 63, issue 7, pages 1234-1247
Published in print January 2006 | ISSN: 1054-3139
Published online January 2006 | e-ISSN: 1095-9289 | DOI:
Genetic and ecological effects of salmon farming on wild salmon: modelling from experimental results

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  • Environmental Science
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Cultured salmonids are released or escape into the wild in large numbers and may make up significant proportions of wild salmonid populations in fresh- and saltwater, causing considerable concern for the fitness and productivity of these populations. This paper focuses on the effects of escaped farmed Atlantic salmon (Salmo salar) on wild salmon. Farmed salmon have been under artificial selection for growth and other economically important traits for 30 years and are genetically different in their origin at the molecular and quantitative genetic levels. Escaped farmed salmon spawn in the wild with limited success. Their offspring outgrow those of wild origin but suffer higher mortality. Whole-river experiments in Ireland and Norway have shown that the lifetime success of farmed salmon is reduced relative to wild salmon. Based on data from these experiments, we model the future of wild salmon populations experiencing invasions of escaped farmed salmon. Simulations with a fixed intrusion rate of 20% escaped farmed salmon at spawning suggest that substantial changes take place in wild salmon populations within ten salmon generations (∼40 years). Low-invasion scenarios suggest that farmed offspring are unlikely to become established in the population, whereas high-invasion scenarios suggest that populations are eventually mixtures of hybrid and farmed descendants. Recovery of the wild population is not likely under all circumstances, even after many decades without further intrusion. Managers of wild salmon will have difficulty in obtaining broodstock of the original wild population after a few generations of high intrusion. We conclude that further measures to reduce escapes of farmed salmon and their spawning in wild populations are urgently needed.

Keywords: aquaculture; Atlantic salmon; competition; domestication; fisheries management; gene flow; maladaptation; migratory fish; population viability; Salmo salar

Journal Article.  9107 words.  Illustrated.

Subjects: Environmental Science ; Marine and Estuarine Biology

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