scholarly journals Widespread genetic introgression of escaped farmed Atlantic salmon in wild salmon populations

2016 ◽  
Vol 73 (10) ◽  
pp. 2488-2498 ◽  
Author(s):  
Sten Karlsson ◽  
Ola H. Diserud ◽  
Peder Fiske ◽  
Kjetil Hindar ◽  
Keyword(s):  
Atlantic Salmon ◽  
Molecular Genetic ◽  
Genetic Introgression ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Geographical Regions ◽  
Average Proportion ◽  
Population Sizes ◽  
Farmed Atlantic Salmon ◽  
High Level

Abstract Farmed Atlantic salmon (Salmo salar) escape from net pens and enter rivers to spawn, potentially resulting in genetic introgression and reduced fitness of wild salmon. Here, we quantify genetic introgression of farmed to wild salmon, using molecular genetic markers, in populations from 147 salmon rivers, representing three-quarters of the total wild salmon spawning population in Norway. For 109 rivers with adult modern samples and sample sizes of 20 or more, the average level of farmed genetic introgression was 6.4% (median = 2.3%), with a range between 0.0% and 42.2%. Fifty-one of these rivers showed significant farmed genetic introgression when compared with historical reference samples. We observed a highly significant correlation between estimated farmed introgression and average proportion of escaped farmed salmon. We quantify levels of introgression as unweighted averages or weighted by population sizes, to compare geographical regions and to compare levels of introgression in rivers and fjords designated as locations deserving a high level of protection. We found a generally lower level of introgression in National Salmon Rivers and National Salmon Fjords subjected to formal protection by parliament. We conclude that farmed to wild genetic introgression is high in a large proportion of Norwegian salmon rivers, with the highest levels found in the most intensive areas of salmon farming. The extensive genetic introgression documented here poses a serious challenge to the management of farmed and wild Atlantic salmon in Norway and, in all likelihood, in other regions where farmed-salmon escape events occur with regularity

scholarly journals Predicting the impacts of escaped farmed Atlantic salmon on wild salmon populations

2018 ◽  
Vol 75 (4) ◽  
pp. 506-512 ◽  
Author(s):  
Freya Keyser ◽  
Brendan F. Wringe ◽  
Nicholas W. Jeffery ◽  
J. Brian Dempson ◽  
Steven Duffy ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Genetic Introgression ◽  
Nucleotide Polymorphisms ◽  
Wild Populations ◽  
Northwest Atlantic ◽  
Wild Salmon ◽  
Facility Locations ◽  
Farmed Salmon ◽  
Farmed Atlantic Salmon ◽  
The Impact

The escape of Atlantic salmon (Salmo salar) from aquaculture facilities can result in both negative genetic and ecological interactions with wild populations, yet the ability to predict the associated risk to wild populations has remained elusive. Here we assess the potential of a spatiotemporal database of aquaculture facility locations, production estimates, and escape events to predict the distribution of escaped farmed salmon and genetic impacts on wild populations in the Northwest Atlantic. Industry production data, reported escape events, and in-river detections of escaped farmed salmon were collected from across the Northwest Atlantic. Genetic estimates of impact were obtained using single nucleotide polymorphisms (95 loci) representing aquaculture and wild salmon throughout the region (30 populations, 3048 individuals). Both the number of escaped farmed salmon detected at counting facilities and the magnitude of genetic impacts were positively correlated with a cumulative spatial measure of aquaculture production. Our results suggest that the risk of escapees and genetic introgression from wild–farmed salmon interactions can be assessed using information on farm production characteristics. This represents a first step in predicting the impact of existing cage-based farms on wild Atlantic salmon.

scholarly journals Evidence of temporal genetic change in wild Atlantic salmon, Salmo salar L., populations affected by farm escapees

2006 ◽  
Vol 63 (7) ◽  
pp. 1224-1233 ◽  
Author(s):  
Øystein Skaala ◽  
Vidar Wennevik ◽  
Kevin A. Glover
Keyword(s):  
Atlantic Salmon ◽  
Genetic Distances ◽  
Genetic Composition ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Farmed Atlantic Salmon ◽  
The Cost ◽  
Genetic Profiles ◽  
Over Time ◽  
Historical Samples

Abstract A large number of farmed Atlantic salmon escape from sea cages and hatcheries annually. Selection programmes and domestication have changed the genetic composition of farmed salmon to improve their performance in the culture environment, which apparently occurs at the cost of their fitness in the natural environment. Therefore, gene flow from farmed salmon to wild salmon populations may have altered the genetic composition of wild salmon populations. To investigate the temporal genetic stability in seven wild Norwegian salmon populations, genetic profiles were produced from historical and contemporary scale samples. Historical and contemporary samples of salmon from the Namsen, Etne, Opo, Vosso, Granvin, Eio, and Hå Rivers were genotyped at the following eight microsatellite loci: Ssa13.37, Ssa28, SsOSL85, Ssa197, Ssa20.19, SsaF43, Ssa202, and Ssa85. A significant change in genetic profiles was observed over time in the Opo, Vosso, and Eio Rivers, but no changes in genetic profiles were observed in the Namsen, Etne, Granvin, and Hå Rivers. A small reduction in FST values and genetic distances among populations was observed in the contemporary samples compared with the historical samples, indicating a eduction in population differentiation over time.

Large-Scale Escapes of Farmed Atlantic Salmon (Salmo salar) into Norwegian Rivers Threaten Natural Populations

1991 ◽  
Vol 48 (3) ◽  
pp. 426-428 ◽  
Author(s):  
D. Gausen ◽  
V. Moen
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Large Scale ◽  
Natural Populations ◽  
Genetic Introgression ◽  
Fish Farms ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
Farmed Atlantic Salmon ◽  
And Behavior

We present data on Atlantic salmon (Salmo salar) which show that escaped farmed salmon enter Norwegian rivers in great numbers. Escaped farmed salmon comprised a substantial proportion of the mature salmon present on the spawning grounds in autumn. A potential for large-scale genetic introgression thus exists. The sex ratios, length distributions, and times of ascent of wild and farmed salmon differed significantly, reflecting major variations in biology and behavior. High proportions of farmed salmon (> 20%) were found only in rivers having fish farms situated closer than 20 km from the outlet.

Prevalence and recurrence of escaped farmed Atlantic salmon (Salmo salar) in eastern North American rivers

2008 ◽  
Vol 65 (12) ◽  
pp. 2807-2826 ◽  
Author(s):  
Matthew R.J. Morris ◽  
Dylan J. Fraser ◽  
Anthony J. Heggelin ◽  
Frederick G. Whoriskey ◽  
Jonathan W. Carr ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
North American ◽  
Temporal Trends ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
In The Wild ◽  
Farmed Atlantic Salmon ◽  
Comprehensive Compilation

Knowledge of the prevalence of escaped farmed fishes in the wild is an essential first step to assessing the risk resulting from interactions between farmed and wild fishes. This is especially important in eastern North America, where Atlantic salmon ( Salmo salar ) aquaculture occurs near wild Atlantic salmon rivers and where many wild salmon populations are severely depressed. Here, we review the literature on the incidence of escaped farmed salmon in eastern North American rivers, for which there has been no comprehensive compilation to date. Escaped farmed salmon have been found in 54 of 62 (87%) rivers investigated within a 300 km radius of the aquaculture industry since 1984, including 11 rivers that contain endangered salmon populations. Averaged among all investigations, the proportional representation of farmed salmon among adults entering the rivers from the sea was 9.2% (range 0% to 100%). Where data were sufficient to examine temporal trends, farmed salmon proportions varied considerably over time, suggesting that escape events are episodic in nature. We conclude that escaped farmed salmon are sufficiently prevalent in eastern North American rivers to pose a potentially serious risk to the persistence of wild salmon populations, especially in those rivers that are adjacent to existing aquaculture sites.

scholarly journals Domesticated escapees on the run: the second-generation monitoring programme reports the numbers and proportions of farmed Atlantic salmon in >200 Norwegian rivers annually

2019 ◽  
Vol 76 (4) ◽  
pp. 1151-1161 ◽  
Author(s):  
K A Glover ◽  
K Urdal ◽  
T Næsje ◽  
H Skoglund ◽  
B Florø-Larsen ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Second Generation ◽  
Fold Increase ◽  
Genetic Introgression ◽  
Marine Aquaculture ◽  
Production Methods ◽  
Farmed Salmon ◽  
Evolutionary Trajectories ◽  
Farmed Atlantic Salmon ◽  
Annual Risk

Abstract Norway is the world’s largest producer of farmed Atlantic salmon and is home to ∼400 rivers containing wild salmon populations. Farmed escapees, a reoccurring challenge of all cage-based marine aquaculture, pose a threat to the genetic integrity, productivity, and evolutionary trajectories of wild populations. Escapees have been monitored in Norwegian rivers since 1989, and, a second-generation programme was established in 2014. The new programme includes data from summer angling, autumn angling, broodstock sampling, and snorkelling surveys in >200 rivers, and >25 000 scale samples are analysed annually. In 2014–2017, escapees were observed in two-thirds of rivers surveyed each year, and between 15 and 30 of the rivers had >10% recorded escapees annually. In the period 1989–2017, a reduction in the proportion of escapees in rivers was observed, despite a >6-fold increase in aquaculture production. This reflected improved escape prevention, and possibly changes in production methods that influence post-escape behaviour. On average, populations estimated to experience the greatest genetic introgression from farmed salmon up to 2014 also had the largest proportions of escapees in 2014–2017. Thus, populations already most affected are those at greatest risk of further impacts. These data feed into the annual risk-assessment of Norwegian aquaculture and form the basis for directing mitigation efforts.

Flavour and off-flavour in wild and farmed atlantic salmon from locations around northern ireland

1995 ◽  
Vol 31 (11) ◽  
pp. 259-264 ◽  
Author(s):  
L. J. Farmer ◽  
J. M. McConnell ◽  
T. D. J. Hagan ◽  
D. B. Harper
Keyword(s):  
Northern Ireland ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Scientific Basis ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
Short Period ◽  
Profiling Techniques ◽  
Farmed Atlantic Salmon

Sensory profiling techniques were used to investigate the odour and flavour of Atlantic salmon (Salmo salar) from six sources in order to determine (i) whether there was any scientific basis for reports of off-flavours in salmon from certain sources and (ii) whether farmed and wild salmon differed in terms of flavour attributes. There were no consistent differences in odour or flavour between sea-caught wild salmon and farmed salmon. However, river-caught wild salmon showed enhanced ‘earthy’ flavour and odour; GC-odour assessment studies have indicated that 2-methylisoborneol and geosmin contribute to these attributes. For a short period, wild river salmon from one source also suffered from a manure-like off-flavour which has been shown to be due to the presence of skatole. The source of this compound remains uncertain.

scholarly journals Escape history and proportion of farmed Atlantic salmon Salmo salar on the coast and in an adjacent salmon fjord in Norway

2020 ◽  
Vol 12 ◽  
pp. 371-383
Author(s):  
T Aronsen ◽  
EM Ulvan ◽  
TF Næsje ◽  
P Fiske
Keyword(s):  
Atlantic Salmon ◽  
Body Length ◽  
Salmo Salar ◽  
Coastal Waters ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Significant Difference ◽  
In The Wild ◽  
The Mean ◽  
Farmed Atlantic Salmon

To gain more knowledge about escaped farmed salmon Salmo salar in the wild, we investigated the proportion of escapees, body length at escape, proportion escaped as smolts/post-smolts (≤300 mm) and number of winters in the wild (winter zones in the growth pattern in the scale samples) in catches on the Norwegian coast and in an adjacent fjord from 2013 to 2017. The mean proportion of escapees was higher on the coast (26%) than in the fjord (4%), and escapees caught on the coast had a slightly larger mean body length at escape (607 mm) than in the fjord (557 mm). However, the mean proportion escaped as smolts/post-smolts did not differ significantly between the coast (8%) and the fjord (11%). There was also no significant difference in the mean proportion of farmed salmon with 1 or more winter zones after escape (50% on the coast and 56% in the fjord). The proportions of escapees with 1, 2, 3 or 4 winter zones after escape were 28, 20, 2 and 0.4% in catches on the coast and 30, 21 and 4% in catches in the fjord, respectively. This study found that the proportion of escapees was considerably higher in coastal waters than in the fjord. Escapees consisted of farmed salmon from several escape events over several years, and approximately 50% of the escapees had one or more winter zones after escape. Thus, escaped farmed salmon may pose a threat to wild salmon populations for several years after the escape event.

Disseminated Intravascular Coagulation in “Hitra Disease” (Hemorrhagic Syndrome) in Farmed Atlantic Salmon

1987 ◽  
Vol 24 (5) ◽  
pp. 378-385 ◽  
Author(s):  
R. Salte ◽  
P. Nafstad ◽  
T. Åsgård
Keyword(s):  
Atlantic Salmon ◽  
Light Microscopy ◽  
Disseminated Intravascular Coagulation ◽  
Hemorrhagic Diathesis ◽  
Wild Salmon ◽  
Intravascular Coagulation ◽  
Farmed Salmon ◽  
Vascular Lumen ◽  
Salmon Parr ◽  
Farmed Atlantic Salmon

Necropsy findings in adult salmon with subclinical “Hitra disease” (hemorrhagic syndrome) varied from negligible to hemorrhagic diathesis with generalized edema. By light microscopy, minute vessels were dilated, arterioles had mural necrosis, and thrombi were present. Occlusions consisted of fused erythrocytes and fibrin. Ultrastructurally, endothelial nuclei were pyknotic with condensed chromatin. The cytoplasm contained numerous laminar structures and electron-dense particles. Damaged erythrocytes adhered to the degenerated endothelium, and coalesced erythrocytes had formed mural thrombi or filled the vascular lumen. Microthrombi were frequently seen. There were no thrombocytes in the thrombi, which consisted of erythrocytes or reticulocytes. Clinically healthy farmed salmon parr showed the same disorders as did adults, but to a far lesser degree. Wild salmon parr had normal microvasculature. Results indicate that disseminated intravascular coagulation (DIC) occurs in “Hitra disease” in farmed Atlantic salmon.

Movements and survival of sonically tagged farmed Atlantic salmon released in Cobscook Bay, Maine, USA

2006 ◽  
Vol 63 (7) ◽  
pp. 1218-1223 ◽  
Author(s):  
Frederick G. Whoriskey ◽  
Paul Brooking ◽  
Gino Doucette ◽  
Stephen Tinker ◽  
Jonathan W. Carr
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Coastal Zone ◽  
Coastal Region ◽  
Movement Patterns ◽  
Tidal Currents ◽  
Bay Of Fundy ◽  
Wild Salmon ◽  
Receiver Array ◽  
Farmed Atlantic Salmon

Abstract We sonically tagged and released farmed Atlantic salmon (Salmo salar) from a cage site in Cobscook Bay, Maine, USA. The fish were released in January (n = 75) and in April and May (n = 198) 2004 to study their movement patterns and survival and to assess the possibility of recapturing them. Inshore and offshore waters in this region are subject to intense tidal currents. Tagged salmon dispersed >1 km from the cage site within a few hours of their release. Mortality was high within Cobscook Bay and the surrounding coastal region (56% of the winter (January) releases; 84% of the spring (March) releases), probably the result of seal predation. Most surviving fish exited the coastal zone and entered the Bay of Fundy along the routes of the dominant tidal currents, passing through Canadian waters. No tagged fish were detected during the wild salmon spawning season in autumn 2004 in any of the 43 monitored salmon rivers draining into the Bay of Fundy, or during 2005 either in the Magaguadavic River, the site of the hatchery in which the fish were reared to the smolt stage, or by a limited coastal receiver array.

scholarly journals Monitoring the incidence of escaped farmed Atlantic salmon, Salmo salar L., in rivers and fisheries of the United Kingdom and Ireland: current progress and recommendations for future programmes

2006 ◽  
Vol 63 (7) ◽  
pp. 1201-1210 ◽  
Author(s):  
Alan M. Walker ◽  
Malcolm C.M. Beveridge ◽  
Walter Crozier ◽  
Niall Ó Maoiléidigh ◽  
Nigel Milner
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Best Practice ◽  
British Isles ◽  
Fish Farms ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
The United Kingdom ◽  
Farmed Atlantic Salmon ◽  
Farming Industry

Abstract An inevitable consequence of the development of the Atlantic salmon, Salmo salar L., farming industry in coastal waters of the British Isles has been the loss of farmed salmon to the wild, their occurrence in inshore waters and rivers, and their appearance in coastal and freshwater fisheries. Monitoring programmes have been developed throughout the British Isles, variously using scientific sampling, catch records from coastal or freshwater fisheries or both, and scientific sampling of catches from in-river traps. We compare the results of these monitoring programmes with regional production and the numbers of escapees reported from marine fish farms. We also consider the effectiveness of the programmes for assessing the prevalence of farmed salmon that escape from marine cages. Finally, we make recommendations for improvements to these programmes and for the development of best practice, including the scientific sampling of in-river spawning stocks through fishery-independent sources, identification of fish origin based on at least two methods, assessment of the degree of incorrect classification, and the timely and accurate reporting of all escapes.

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