A1 Refereed original research article in a scientific journal
Captive-bred Atlantic salmon released into the wild have fewer offspring than wild-bred fish and decrease population productivity
Authors: O'Sullivan RJ, Aykanat T, Johnston SE, Rogan G, Poole R, Prodohl PA, de Eyto E, Primmer CR, McGinnity P, Reed TE
Publisher: ROYAL SOC
Publication year: 2020
Journal: Proceedings of the Royal Society B: Biological Sciences
Journal name in source: PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
Journal acronym: P ROY SOC B-BIOL SCI
Article number: ARTN 20201671
Volume: 287
Issue: 1937
Number of pages: 8
ISSN: 0962-8452
eISSN: 1471-2954
DOI: https://doi.org/10.1098/rspb.2020.1671
Web address : https://doi.org/10.1098/rspb.2020.1671
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/51778532
The release of captive-bred animals into the wild is commonly practised to restore or supplement wild populations but comes with a suite of ecological and genetic consequences. Vast numbers of hatchery-reared fish are released annually, ostensibly to restore/enhance wild populations or provide greater angling returns. While previous studies have shown that captive-bred fish perform poorly in the wild relative to wild-bred conspecifics, few have measured individual lifetime reproductive success (LRS) and how this affects population productivity. Here, we analyse data on Atlantic salmon from an intensely studied catchment into which varying numbers of captive-bred fish have escaped/been released and potentially bred over several decades. Using a molecular pedigree, we demonstrate that, on average, the LRS of captive-bred individuals was only 36% that of wild-bred individuals. A significant LRS difference remained after excluding individuals that left no surviving offspring, some of which might have simply failed to spawn, consistent with transgenerational effects on offspring survival. The annual productivity of the mixed population (wild-bred plus captive-bred) was lower in years where captive-bred fish comprised a greater fraction of potential spawners. These results bolster previous empirical and theoretical findings that intentional stocking, or non-intentional escapees, threaten, rather than enhance, recipient natural populations.
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