A comparison of farmed, wild and hybrid Atlantic salmon (Salmo salar L.) reared under farming conditions

Glover, Kevin A.; Otterå, Håkon; Olsen, Rolf Erik; Slinde, Erik; Taranger, Geir Lasse; Skaala, Øystein

doi:10.1016/j.aquaculture.2008.09.023

Cited by 112 publications

(159 citation statements)

References 47 publications

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“…However, size differences between farm and wild juveniles were similar in the hatchery environment as in the wild (Table 2), which contrasts with the above-cited studies. This presumably reflects the fact that the Fanad farm strain used in our study had experienced a different selection trajectory in Ireland up until our experiments were carried out in the 1990 s than the Norwegian farm strains used in the more recent Norwegian studies had (Glover et al, 2009;Skaala et al, 2012;Solberg et al, 2013a,b). The latter had also undergone more generations of targeted artificial (and/or inadvertent domestication) selection than our farm strain.…”

Section: Discussionmentioning

confidence: 83%

“…Genetic basis of group and family differences in size-at-age Directional selection in farm strains has resulted in higher intrinsic growth rates of farm salmon, which in a hatchery environment can grow up to three times faster than wild salmon (Glover et al, 2009;Solberg et al, 2013a, b). However, these growth rate differences seem to be less pronounced in wild stream environments and in hatchery conditions simulating a semi-natural environment with restricted food (Solberg et al, 2013a).…”

Section: Discussionmentioning

confidence: 99%

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Quantifying heritable variation in fitness-related traits of wild, farmed and hybrid Atlantic salmon families in a wild river environment

et al. 2015

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Farmed fish are typically genetically different from wild conspecifics. Escapees from fish farms may contribute one-way gene flow from farm to wild gene pools, which can depress population productivity, dilute local adaptations and disrupt coadapted gene complexes. Here, we reanalyse data from two experiments (McGinnity et al., 1997(McGinnity et al., , 2003 where performance of Atlantic salmon (Salmo salar) progeny originating from experimental crosses between farm and wild parents (in three different cohorts) were measured in a natural stream under common garden conditions. Previous published analyses focussed on group-level differences but did not account for pedigree structure, as we do here using modern mixed-effect models. Offspring with one or two farm parents exhibited poorer survival in their first and second year of life compared with those with two wild parents and these group-level inferences were robust to excluding outlier families. Variation in performance among farm, hybrid and wild families was generally similar in magnitude. Farm offspring were generally larger at all life stages examined than wild offspring, but the differences were moderate (5-20%) and similar in magnitude in the wild versus hatchery environments. Quantitative genetic analyses conducted using a Bayesian framework revealed moderate heritability in juvenile fork length and mass and positive genetic correlations (40.85) between these morphological traits. Our study confirms (using more rigorous statistical techniques) previous studies showing that offspring of wild fish invariably have higher fitness and contributes fresh insights into family-level variation in performance of farm, wild and hybrid Atlantic salmon families in the wild. It also adds to a small, but growing, number of studies that estimate key evolutionary parameters in wild salmonid populations. Such information is vital in modelling the impacts of introgression by escaped farm salmon.

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Quantifying heritable variation in fitness-related traits of wild, farmed and hybrid Atlantic salmon families in a wild river environment

et al. 2015

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“…For example, they out-grow wild salmon under hatchery conditions (Glover et al 2009, Solberg et al 2013a. Wild salmon populations are regarded as potentially adapted to their natal rivers (Garcia de Leaniz et al 2007, Fraser et al 2011, and the survival of farmed salmon offspring in the wild is lower than for native salmon (McGinnity et al 1997, 2003, Fleming et al 2000.…”

Section: Introductionmentioning

confidence: 99%

Genetic introgression of farmed salmon in native populations: quantifying the relative influence of population size and frequency of escapees

Heino¹,

Svåsand²,

Wennevik³

et al. 2015

Aquacult. Environ. Interact.

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Farmed escapees may threaten the genetic integrity of native salmon populations through interbreeding. However, introgression requires survival until maturation, successful reproduction and successful early development. These traits are often compromised in domesticated animals selected for high performance in captivity. This makes it difficult to predict introgression levels in native populations. A recent study estimated genetic introgression of farmed escaped Atlantic salmon Salmo salar in 20 Norwegian rivers and found highly population-specific levels of introgression. The underlying causes of these patterns, however, remain unknown. Here, using a modeling approach on empirical and demographic data, we demonstrated that a combination of the observed relative frequency of escaped farmed salmon and the average annual angling catch weights for rivers, provides a significantly better predictor for cumulative introgression of farmed salmon in wild populations than the frequency of farmed salmon alone. Our results suggest that the demography of the native population is a significant factor influencing the relative success of farmed salmon in the wild.

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“…Furthermore, the low genetic differentiation between historical and contemporary samples, as measured by Fst and the large differences in growth between salmon from the River Etneelva and farmed salmon under controlled conditions (Glover et al 2009) strongly suggests that this population has so far experienced little genetic introgression from farmed salmon. In summary, the major threats to anadromous populations in the Hardangerfjord appear to be degradation of the freshwater habitat, increased mortality due to high levels of salmon lice infection derived from fish farms, particularly in anadromous brown trout, and reduced production of wild salmon due to genetic introgression from escapees.…”

Section: Major Population Threatsmentioning

confidence: 99%

A conservation plan for Atlantic salmon (Salmo salar) and anadromous brown trout (Salmo trutta) in a region with intensive industrial use of aquatic habitats, the Hardangerfjord, western Norway

Skaala

Johnsen²,

et al. 2013

Marine Biology Research

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Extensive use of aquatic habitats, mainly for hydropower and aquaculture, has a negative impact on anadromous salmonid populations of the Hardangerfjord region, western Norway. High infection levels of salmon lice, and high proportions of escaped farmed salmon in spawning rivers, appear to violate the goals in the 'Strategy for an Environmentally Sustainable Aquaculture Industry' set by the Norwegian government. An overview of the anadromous populations in the fjord, their status and the major threats are presented. A conservation plan with mitigation efforts consisting of seven steps is presented: (1) genetic assessment of Atlantic salmon and anadromous brown trout populations, (2) reducing gene flow from escapees, (3) reducing infection pressure from salmon lice, (4) conduct an assessment of the freshwater habitats for anadromous salmonids and then implement it in order to restore smolt production, (5) efforts to reduce risk of river pollution from agriculture and industry and minimize impacts from hydropower production, (6) when and where necessary and practical, plant out eyed eggs from the Norwegian Genebank to increase parr and smolt production, and finally, (7) monitor spawning populations and parr densities to evaluate potential effects of the mitigation efforts. Experience and knowledge gained through the plan will be useful for other regions with similar challenges. We call for an initiative to establish a national fund under democratic and public control, where funding can be obtained for projects which focus on mitigation efforts and conservation of salmonid populations.

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A comparison of farmed, wild and hybrid Atlantic salmon (Salmo salar L.) reared under farming conditions

Cited by 112 publications

References 47 publications

Quantifying heritable variation in fitness-related traits of wild, farmed and hybrid Atlantic salmon families in a wild river environment

Quantifying heritable variation in fitness-related traits of wild, farmed and hybrid Atlantic salmon families in a wild river environment

Genetic introgression of farmed salmon in native populations: quantifying the relative influence of population size and frequency of escapees

A conservation plan for Atlantic salmon (Salmo salar) and anadromous brown trout (Salmo trutta) in a region with intensive industrial use of aquatic habitats, the Hardangerfjord, western Norway

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