Plasticity in growth of farmed and wild Atlantic salmon:Is the increased growth rate of farmed salmon caused by evolutionary adaptations to the commercial diet?

Harvey, Alison Catherine, Solberg, Monica Favnebøe, Troianou, Eva, Carvalho, Gary Robert, Taylor, Martin Ian ORCID: https://orcid.org/0000-0002-3858-0712, Creer, Simon, Dyrhovden, Lise, Matre, Ivar Helge and Glover, Kevin Alan (2016) Plasticity in growth of farmed and wild Atlantic salmon:Is the increased growth rate of farmed salmon caused by evolutionary adaptations to the commercial diet? BMC Evolutionary Biology, 16. ISSN 1471-2148

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Abstract

Background: Domestication of Atlantic salmon for commercial aquaculture has resulted in farmed salmon displaying substantially higher growth rates than wild salmon under farming conditions. In contrast, growth differences between farmed and wild salmon are much smaller when compared in the wild. The mechanisms underlying this contrast between environments remain largely unknown. It is possible that farmed salmon have adapted to the high-energy pellets developed specifically for aquaculture, contributing to inflated growth differences when fed on this diet. We studied growth and survival of 15 families of farmed, wild and F1 hybrid salmon fed three contrasting diets under hatchery conditions; a commercial salmon pellet diet, a commercial carp pellet diet, and a mixed natural diet consisting of preserved invertebrates commonly found in Norwegian rivers.  Results: For all groups, despite equal numbers of calories presented by all diets, overall growth reductions as high 68 and 83%, relative to the salmon diet was observed in the carp and natural diet treatments, respectively. Farmed salmon outgrew hybrid (intermediate) and wild salmon in all treatments. The relative growth difference between wild and farmed fish was highest in the carp diet (1: 2.1), intermediate in the salmon diet (1:1.9) and lowest in the natural diet (1:1.6). However, this trend was non-significant, and all groups displayed similar growth reaction norms and plasticity towards differing diets across the treatments.  Conclusions: No indication of genetic-based adaptation to the form or nutritional content of commercial salmon diets was detected in the farmed salmon. Therefore, we conclude that diet alone, at least in the absence of other environmental stressors, is not the primary cause for the large contrast in growth differences between farmed and wild salmon in the hatchery and wild. Additionally, we conclude that genetically-increased appetite is likely to be the primary reason why farmed salmon display higher growth rates than wild salmon when fed ad lib rations under hatchery conditions. Our results contribute towards an understanding of the potential genetic changes that have occurred in farmed salmon in response to domestication, and the potential mechanisms underpinning genetic and ecological interactions between farmed escapees and wild salmonids.

Item Type:	Article
Additional Information:	This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Uncontrolled Keywords:	domestication,farm escapes,genetic interaction,hybridisation,reaction norms,survival ,salmonids,pellets,natural diet,feed utilisation,appetite
Faculty \ School:	Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Organisms and the Environment
Depositing User:	Pure Connector
Date Deposited:	17 Dec 2016 00:07
Last Modified:	12 May 2023 00:26
URI:	https://ueaeprints.uea.ac.uk/id/eprint/61761
DOI:	10.1186/s12862-016-0841-7

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