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.

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 Does density influence relative growth performance of farm, wild and F 1 hybrid Atlantic salmon in semi-natural and hatchery common garden conditions?

2016 ◽  
Vol 3 (7) ◽  
pp. 160152 ◽  
Author(s):  
Alison C. Harvey ◽  
Gareth Juleff ◽  
Gary R. Carvalho ◽  
Martin I. Taylor ◽  
Monica F. Solberg ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Natural Environment ◽  
Common Garden ◽  
High Density ◽  
Lower Growth ◽  
Relative Growth ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
In The Wild

The conditions encountered by Atlantic salmon, Salmo salar L., in aquaculture are markedly different from the natural environment. Typically, farmed salmon experience much higher densities than wild individuals, and may therefore have adapted to living in high densities. Previous studies have demonstrated that farmed salmon typically outgrow wild salmon by large ratios in the hatchery, but these differences are much less pronounced in the wild. Such divergence in growth may be explained partly by the offspring of wild salmon experiencing higher stress and thus lower growth when compared under high-density farming conditions. Here, growth of farmed, wild and F 1 hybrid salmon was studied at contrasting densities within a hatchery and semi-natural environment. Farmed salmon significantly outgrew hybrid and wild salmon in all treatments. Importantly, however, the reaction norms were similar across treatments for all groups. Thus, this study was unable to find evidence that the offspring of farmed salmon have adapted more readily to higher fish densities than wild salmon as a result of domestication. It is suggested that the substantially higher growth rate of farmed salmon observed in the hatchery compared with wild individuals may not solely be caused by differences in their ability to grow in high-density hatchery scenarios.

scholarly journals Using simulated escape events to assess the annual numbers and destinies of escaped farmed Atlantic salmon of different life stages from farm sites in Norway

2014 ◽  
Vol 72 (2) ◽  
pp. 670-685 ◽  
Author(s):  
Ove T. Skilbrei ◽  
Mikko Heino ◽  
Terje Svåsand
Keyword(s):  
Atlantic Salmon ◽  
Release Site ◽  
Environmental Risks ◽  
Fish Farms ◽  
Farmed Salmon ◽  
Open Sea ◽  
In The Wild ◽  
The Mean ◽  
Farmed Atlantic Salmon ◽  
Immature Fish

Abstract To improve assessments of the environmental risks of aquaculture, a series of simulated escapes of farmed Atlantic salmon (Salmo salar L.) from seawater netpens were performed. Individually tagged post-smolts and adult Atlantic salmon were released from various locations at different times of the year. Post-smolts that escaped during their first summer were capable of rapid migration towards the open sea. A small fraction returned to spawn and were recaptured after 1–3 years at sea (0.4%, range 0.0–1.1%). A total of 13% of the post-smolts that escaped during autumn were reported in nearby fisheries during subsequent months, partly because they had grown large enough to be caught in the gillnets used, but more importantly because migratory behaviour diminished towards the end of the year. The mean recapture rate of adult salmon was high after releases in fjords (7–33%), lower after coastal releases (4–7%), and zero on the outer coast. Most of these recaptures were immature fish recaptured in sea relatively close to the release site during their first months post-release. Recaptures of adult escapees after 1–2 years in the wild were very rare (0.09%), probably because of their low survival. A Monte-Carlo method was developed to estimate the annual numbers of escapees from Norwegian fish farms based on reported catches of escaped farmed salmon in the sea and in rivers and the recapture probabilities reported here. The model provides a tool to estimate numbers of escapees independently from the reported numbers. Importantly, our analysis suggests that the total numbers of post-smolt and adult escapees have been two- to fourfold as high as the numbers reported to the authorities by fish farmers, depending on whether the incomplete sea fishery statistics are compensated for.

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.

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.

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 Relationships between the frequency of farmed Atlantic salmon, Salmo salar L., in wild salmon populations and fish farming activity in Norway, 1989–2004

2006 ◽  
Vol 63 (7) ◽  
pp. 1182-1189 ◽  
Author(s):  
Peder Fiske ◽  
Roar A. Lund ◽  
Lars P. Hansen
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Negative Impact ◽  
Fish Farming ◽  
County Level ◽  
Salmon Farming ◽  
Farmed Salmon ◽  
Catch Statistics ◽  
Farmed Atlantic Salmon ◽  
The Impact

Abstract In Norway, there have been restrictions on salmon farming in several fjords to reduce the potential negative impact on important stocks of wild Atlantic salmon. Little is known about the incidence of escaped farmed salmon in fisheries and broodstocks relative to the extent of fish farming in nearby areas. In this study, we analysed data on the incidence of escaped farmed Atlantic salmon in angling catches and broodstock fisheries in rivers for a 16-year period (1989–2004). These data were weighted using official catch statistics and combined at the county level, and the incidence of escapees was correlated with both the stock of farmed salmon in net pens and the reported number of escapees in different Norwegian counties. Our results indicate a significant positive correlation between the incidence of escaped farmed salmon in the rivers at the county level and the intensity of salmon farming, measured as the number of farmed salmon in net pens, suggesting that protection areas may reduce the impact of escapees in salmon populations nearby.

Performance of farmed, hybrid, and wild Atlantic salmon (Salmo salar) families in a natural river environment

2012 ◽  
Vol 69 (12) ◽  
pp. 1994-2006 ◽  
Author(s):  
Øystein Skaala ◽  
Kevin A. Glover ◽  
Bjørn T. Barlaup ◽  
Terje Svåsand ◽  
Francois Besnier ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Rates ◽  
Egg Size ◽  
Relative Survival ◽  
Hybrid Progeny ◽  
Wild Salmon ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
Sib Families

Survival, growth, and diet were compared for farmed, hybrid, and wild Atlantic salmon (Salmo salar) families from the eyed egg to the smolt stage in River Guddalselva, Hardangerfjord, Norway. All individuals that survived until the smolt stage were captured in a Wolf trap and identified to one of the 69 experimental families using microsatellite markers. Survival of farmed salmon progeny was significantly lower than that of hybrids and wild progeny. However, survival varied considerably, from 0.17% to 6.4%, among farmed families. Egg size had an important influence on survival. Half-sib hybrid families with a farmed mother had higher survival when fathered by wild salmon than by farmed salmon. The overall relative survival of farmed families compared with that of their hybrid half-sib families fell from 0.86 in the second cohort to 0.62 in the last cohort with increasing fish density. Smolts of farmed parents showed significantly higher growth rates than wild and hybrid smolts. The overlap in diet among types of crosses demonstrates competition, and farm and hybrid progeny therefore will reduce the river’s capacity for production of wild 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.

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