Genetic analysis of Atlantic salmon captured in a netting station reveals multiple escapement events from commercial fish farms

Zhang, Zhiwei; Glover, Kevin A.; Wennevik, Vidar; Svåsand, Terje; Sørvik, Anne Grete Eide; Fiske, Peder; Karlsson, Sten; Skaala, Øystein

doi:10.1111/fme.12002

Cited by 17 publications

(14 citation statements)

References 59 publications

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“…5). The larger genetic variation (total number of alleles, allelic richness) observed among the escapees in relation to the neighbouring farms further supports this aforementioned mixed origin (Skaala et al 2004), an issue that has already been invoked in former escape episodes (Zhang et al 2013). The higher percentage of individuals of 'Unknown', and hence, mixed origin is particularly relevant in Etne and explains why this sample shows larger genetic variation and effective population size than any of the remaining ones.…”

Section: Discussionsupporting

confidence: 63%

“…In order to address this issue, Glover et al (2008) developed a method based upon genetic assignment statistics called the 'DNA stand-by-method', which permits the identification of the farm of origin for salmon escapees. This method has been under continuous development since its successful implementation in 2007 (Glover et al 2009, 2011b, 2013a, Glover 2010, Zhang et al 2013, and it is now commonly applied in cases of unreported escapes of farmed fish in Norway. However, it is sometimes not possible to conclusively differentiate between 2 or more potential farm sources that rear fish with a similar genetic background.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Siblingship tests connect two seemingly independent farmed Atlantic salmon escape events

Quintela¹,

Wennevik²,

Sørvik³

et al. 2016

Aquacult. Environ. Interact.

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Aquaculture escapees represent a threat to the genetic integrity of native populations, may spread infectious agents and display ecological interactions with wild fish. DNA-based identification methods are well established for tracing Atlantic salmon escapees back to their farms of origin. However, traditional genetic assignment approaches are not always able to single out the farm of origin in cases where several potential farm sources rear fish from the same genetic line, and display strongly overlapping allele frequencies. We investigated whether an alternative statistical approach, which involves ad hoc identification of sibling relationships, circumvents the challenge of overlapping allele frequencies. We analysed the following samples collected in 2013: (1) 221 farmed escapees captured in several rivers in the Ryfylke region of Norway, (2) 139 farmed escapees captured some 150 km away in an upstream fish migration trap in the River Etne, and (3) 779 farmed salmon sampled from 17 cages on 10 farms in Ryfylke. Siblingship tests increased the precision of identification of escapees back to their farm of origin over genetic assignment and population statistic approaches. Together with other non-genetic data, siblingship tests were also able to connect 2 seemingly independent escape events, demonstrating that some of the salmon escaping from 1 or 2 farms in Ryfylke took approximately 1 mo to migrate 150 km northwards before entering the River Etne. Finally, we demonstrated that the genetic background of the escapees captured in the River Etne during the course of an entire season was represented by the 3 major breeding programs in Norway.

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Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Siblingship tests connect two seemingly independent farmed Atlantic salmon escape events

Quintela¹,

Wennevik²,

Sørvik³

et al. 2016

Aquacult. Environ. Interact.

View full text Add to dashboard Cite

show abstract

“…This is because a cage on a commercial farm typically contains fish resulting from a low or relatively low number of families and does therefore not accurately represent the genetic diversity nor allele frequencies of the actual farmed strain itself. The reader is referred to the following publications for data related to variation in allele profiles between cages on and among fish farms (Glover et al., ; Glover, Hansen, & Skaala, ; Glover, Skaala, Sovik, & Helle, ; Zhang et al., ). F, farm, W, wild, D, domesticated (combination of farmed and hatchery‐reared fish).…”

Section: Geneticsmentioning

confidence: 99%

Half a century of genetic interaction between farmed and wild Atlantic salmon: Status of knowledge and unanswered questions

et al. 2017

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Atlantic salmon (Salmo salar) is one of the best researched fishes, and its aquaculture plays a global role in the blue revolution. However, since the 1970s, tens of millions of farmed salmon have escaped into the wild. We review current knowledge of genetic interactions and identify the unanswered questions. Native salmon populations are typically genetically distinct from each other and potentially locally adapted. Outside Norway, introgression remains unquantified, and in all regions, biological changes and the mechanisms driving population-specific impacts remain poorly documented. Nevertheless, existing knowledge shows that the long-term consequences of introgression is expected to lead to changes in life-history traits, reduced population productivity and decreased resilience to future challenges. Only a major reduction in the number of escapees and/or sterility of farmed salmon can eliminate further impacts. K E Y W O R D Saquaculture, evolution, fish farming, fitness, genetic, hybrid

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“…According to Norwegian escape statistics, < 4% of escapees escaped as smolts between 2005 and 2011 (Skilbrei et al 2015). However, escaped salmon can leave the net pens unreported and possibly also undetected by the fish farmer (Skilbrei & Wennevik 2006, Glover 2010, Zhang et al 2013, and therefore estimates of actual escapes of both smolts and adults are significantly higher than reported numbers (Skilbrei et al 2015). Knowledge of the escape history of these salmon is important for risk assessments and for the development of strategies to prevent future escapes and reduce their ecological impacts.…”

Section: Introductionmentioning

confidence: 99%

Use of fatty acid profiles to monitor the escape history of farmed Atlantic salmon

Skilbrei¹,

Normann²,

Meier³

et al. 2015

Aquacult. Environ. Interact.

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Farmed Atlantic salmon can escape from fish farms at various stages of their life, from juveniles to large mature fish. Escapees that enter rivers to spawn pose a threat to the genetic integrity of wild populations. Knowledge about the timing of these escapes can provide important information for wildlife management and the aquaculture industry, enabling them to prevent or mitigate the negative impacts of escapees. Farmed salmon food has a high content of terrestrial lipids; thus, we used fatty acid (FA) profiling to monitor the escape history of farmed salmon. Escaped salmon captured in rivers (n = 251) presented a wide range of FA profiles that we used to classify the fish as (1) early-escaped wild-like fish that were assumed to have escaped at smolt or early post-smolt stage (24%), (2) recently escaped fish with high levels of FAs typically found in commercial salmon food (61%) and (3) intermediate escapees whose FA profiles lay between those 2 groups (15%). To estimate the size at escape of the intermediate escapees, we performed a feeding experiment that monitored the development of FA profiles after a shift in diet from terrestrial to marine lipids. Most intermediate escapees appeared to have escaped when they were < 3 kg, and ranged from 3 to 11 kg when recaptured in rivers. We conclude that FA profiling is a promising tool to monitor escape histories, and that the proportion of post-smolt escapees in this study was high compared to official escape statistics which include very few reports of young fish escaping.

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Genetic analysis of Atlantic salmon captured in a netting station reveals multiple escapement events from commercial fish farms

Cited by 17 publications

References 59 publications

Siblingship tests connect two seemingly independent farmed Atlantic salmon escape events

Siblingship tests connect two seemingly independent farmed Atlantic salmon escape events

Half a century of genetic interaction between farmed and wild Atlantic salmon: Status of knowledge and unanswered questions

Use of fatty acid profiles to monitor the escape history of farmed Atlantic salmon

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