scholarly journals Effects of aquaculture on wild fish populations: a synthesis of data

2005 ◽  
Vol 13 (4) ◽  
pp. 145-168 ◽  
Author(s):  
Laura K Weir ◽  
James WA Grant
Keyword(s):  
Atlantic Salmon ◽  
Artificial Selection ◽  
Scientific Literature ◽  
Current Data ◽  
Wild Fish ◽  
Fish Populations ◽  
Negative Consequences ◽  
Wild Populations ◽  
Farmed Fish ◽  
In The Wild

The potential adverse environmental effects of aquaculture have been the subject of considerable attention in both the media and the scientific literature. We undertook a synthesis of the published scientific literature, primarily concerning Atlantic salmon (Salmo salar), to assess the current data available regarding these potential effects. No data are available to test for the direct effects of aquaculture organisms on the demographics of wild fish populations. However, seven studies show that escaped salmon in the wild have lower fitness, as measured by survival and reproductive success, than native salmon. Thirteen other studies, encompassing 91 different traits, provide strong evidence of phenotypic differences between farmed and wild salmon, presumably because of artificial selection in the aquaculture environment. An additional 10 studies have documented significant genetic differences between farmed salmon and the wild fish with which they will interact, or potentially interact. Given the paucity of data regarding actual population consequences of escaped farmed fish on wild populations, and the documented differences between the two types of fish, it seems prudent to treat farmed fish as exotic species with potentially negative consequences for wild populations, particularly when the latter are of conservation concern.Key words: aquaculture, Atlantic salmon, artificial selection, fitness, introgression.

scholarly journals Captive-bred Atlantic salmon released into the wild have fewer offspring than wild-bred fish and decrease population productivity

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201671
Author(s):  
Ronan James O'Sullivan ◽  
Tutku Aykanat ◽  
Susan E. Johnston ◽  
Ger Rogan ◽  
Russell Poole ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Natural Populations ◽  
Mixed Population ◽  
Lifetime Reproductive Success ◽  
Wild Relative ◽  
Offspring Survival ◽  
Wild Populations ◽  
Annual Productivity ◽  
In The Wild ◽  
Analyse Data

The release of captive-bred animals into the wild is commonly practised to restore or supplement wild populations but comes with a suite of ecological and genetic consequences. Vast numbers of hatchery-reared fish are released annually, ostensibly to restore/enhance wild populations or provide greater angling returns. While previous studies have shown that captive-bred fish perform poorly in the wild relative to wild-bred conspecifics, few have measured individual lifetime reproductive success (LRS) and how this affects population productivity. Here, we analyse data on Atlantic salmon from an intensely studied catchment into which varying numbers of captive-bred fish have escaped/been released and potentially bred over several decades. Using a molecular pedigree, we demonstrate that, on average, the LRS of captive-bred individuals was only 36% that of wild-bred individuals. A significant LRS difference remained after excluding individuals that left no surviving offspring, some of which might have simply failed to spawn, consistent with transgenerational effects on offspring survival. The annual productivity of the mixed population (wild-bred plus captive-bred) was lower in years where captive-bred fish comprised a greater fraction of potential spawners. These results bolster previous empirical and theoretical findings that intentional stocking, or non-intentional escapees, threaten, rather than enhance, recipient natural populations.

The costs of habitat utilization of wild, farmed, and domesticated juvenile Atlantic salmon (Salmo salar)

2004 ◽  
Vol 61 (12) ◽  
pp. 2302-2313 ◽  
Author(s):  
Eva C Enders ◽  
Daniel Boisclair ◽  
André G Roy
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
First Generation ◽  
Wild Fish ◽  
Farmed Fish ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Generation Progeny ◽  
High Turbulence ◽  
Wild Progenitors

We compared morphometry and total swimming costs of wild, farmed (first-generation hatchery progeny of wild progenitors) and domesticated (seventh-generation progeny of the Norwegian aquaculture strain) juvenile Atlantic salmon (Salmo salar). Respirometry experiments were performed to assess total swimming costs of fish ranging in size from 4.0 to 16.1 g wet mass at a water temperature of 15 °C. Fish were subjected to flow conditions of low and high turbulence. Total swimming costs increased significantly with intensity of turbulence and were, on average, 1.4 times higher at high than at low turbulence. Total swimming costs were 2.4- to 4.0-fold higher than predicted by forced swimming models developed under conditions that minimize flow heterogeneity. Total swimming costs of wild and farmed fish were not statistically different (average difference = 6.7%). Hence, swimming costs models developed using farmed fish may be used to estimate swimming costs of wild fish. However, domesticated fish had total swimming costs 12.0% to 29.2% higher than farmed or wild fish. This may be related to domesticated fish having deeper bodies and smaller fins.

scholarly journals Activities for Prevention of Gyrodactylus Salaris Distribution in the Kola Peninsula Rivers

2020 ◽  
Author(s):  
Natalia Kalinina ◽  
Petr Kravets
Keyword(s):  
Atlantic Salmon ◽  
Kola Peninsula ◽  
Barents Sea ◽  
Natural Populations ◽  
Wild Populations ◽  
Farmed Fish ◽  
Scientific Organizations ◽  
Northwest Europe ◽  
Baltic Sea Basin ◽  
Working Out

Monitoring of distribution of monogenean ectoparasite Gyrodactylus salaris, dangerous for wild populations of the Atlantic salmon in northwest Europe, is carried out by Veterinary Services and the profile scientific organizations in different European countries. In Murmansk area, Gyrodactylus lavareti was first found in a trout farm in Tuloma River in 1996. From now on, representatives of genus Gyrodactylus are annually identified in farmed fish in Tuloma River, according to ichthyopatholocic observations of salmonid farms in Murmansk area. Species G. salaris was indicated in 2016 in farmed trout in Tuloma River and in wild salmon smolts in Pak River of the Nizhnetulomsky water basin. Throughout a number of years, the experts of Regional Veterinary Service and the scientific organizations of Murmansk area discuss necessity of working out of measures to prevent Gyrodactylus salaris introduction in the rivers of the Kola Peninsula with wild populations of the Atlantic salmon. Any transport of smolt and live fish from the freshwater objects of Baltic Sea basin to the water objects of the Barents Sea basin sea would become the most significant threat by parasite Gyrodactylus salaris distribution and might cause a damage of natural populations of the Atlantic salmon of Kola Peninsula.

scholarly journals Salmon lice increase the age of returning Atlantic salmon

2014 ◽  
Vol 10 (1) ◽  
pp. 20130896 ◽  
Author(s):  
Knut Wiik Vollset ◽  
Bjørn Torgeir Barlaup ◽  
Helge Skoglund ◽  
Eirik Straume Normann ◽  
Ove Tommy Skilbrei
Keyword(s):  
Atlantic Salmon ◽  
Life History Traits ◽  
Age Distribution ◽  
Wild Populations ◽  
Age At Maturity ◽  
Farmed Fish ◽  
Parasite Abundance ◽  
Salmon Lice ◽  
Global Increase ◽  
Host Parasite

The global increase in the production of domestic farmed fish in open net pens has created concerns about the resilience of wild populations owing to shifts in host–parasite systems in coastal ecosystems. However, little is known about the effects of increased parasite abundance on life-history traits in wild fish populations. Here, we report the results of two separate studies in which 379 779 hatchery-reared Atlantic salmon smolts were treated (or not) against salmon lice, marked and released. Adults were later recaptured, and we specifically tested whether the age distribution of the returning spawners was affected by the treatment. The estimates of parasite-induced mortality were 31.9% and 0.6% in the River Vosso and River Dale stock experiments, respectively. Age of returning salmon was on average higher in treated versus untreated fish. The percentages of fish returning after one winter at sea were 37.5% and 29.9% for the treated and untreated groups, respectively. We conclude that salmon lice increase the age of returning salmon, either by affecting their age at maturity or by disproportionately increasing mortality in fish that mature early.

scholarly journals Fitness-related consequences of competitive interactions between farmed and wild Atlantic salmon at different proportional representations of wild–farmed hybrids

2009 ◽  
Vol 67 (4) ◽  
pp. 657-667 ◽  
Author(s):  
Aimee Lee S. Houde ◽  
Dylan J. Fraser ◽  
Jeffrey A. Hutchings
Keyword(s):  
Atlantic Salmon ◽  
Life Stage ◽  
Wild Fish ◽  
Competitive Interactions ◽  
Test Results ◽  
Farmed Fish ◽  
Farmed Salmon ◽  
Natural Stream ◽  
Two Populations ◽  
Pairwise Test

Abstract Houde, A. S., Fraser, D. J., and Hutchings, J. A. 2010. Fitness-related consequences of competitive interactions between farmed and wild Atlantic salmon at different proportional representations of wild–farmed hybrids. – ICES Journal of Marine Science, 67: 657–667. Escaped farmed fish possess heritable characteristics that may give them and their wild–farmed hybrid offspring a competitive advantage over wild fish. Limited research has examined whether the results of wild vs. farmed pairwise behavioural contests can predict the change in fitness-related traits of wild fish when exposed to wild–farmed hybrids, or to different proportions of such hybrids, within stream environments. Pairwise aggression tests on North American Atlantic salmon (Salmo salar) revealed that regional farmed salmon and wild–farmed hybrids (F1, F2, and wild backcrosses) were more competitive than wild fish from two divergent populations. The ranking by which hybrids differed in competitive ability from wild fish also depended on the wild population. However, the magnitude of change in fitness-related traits of wild fish, such as mortality, size, and condition, from the same two populations could not be predicted from pairwise test results when replicate groups of wild fish were exposed to different proportions of hybrids (wild:hybrid ratios of 50:50, 70:30, and 85:15) in semi-natural stream environments. Notably, there was greater mortality of both wild and hybrid fish in treatments containing 30% hybrids for both populations; at a composition of 50% hybrids, the mortality of wild fish in one population increased more than it did in the other. The results suggest that for the life stage examined and provided the rate of farmed intrusion and wild–farmed interbreeding remains low (i.e. ≤15% hybrids), the effects of competitive interaction with their farmed counterparts may have comparatively little effect on the mortality of wild populations.

Potential for domesticated–wild interbreeding to induce maladaptive phenology across multiple populations of wild Atlantic salmon (Salmo salar)

2010 ◽  
Vol 67 (11) ◽  
pp. 1768-1775 ◽  
Author(s):  
Dylan J. Fraser ◽  
Cóilín Minto ◽  
Anna M. Calvert ◽  
James D. Eddington ◽  
Jeffrey A. Hutchings
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Common Garden ◽  
Developmental Rate ◽  
Wild Populations ◽  
Southern Limit ◽  
Farmed Salmon ◽  
Atlantic Salmon Salmo Salar ◽  
In The Wild ◽  
Developmental Rates

We report how aquaculture may negatively alter a critical phenological trait (developmental rate) linked to survival in wild fish populations. At the southern limit of the species range in eastern North America, the persistence of small Atlantic salmon ( Salmo salar ) populations may be constrained by interbreeding with farmed salmon that escape regularly from intensive aquaculture facilities. Using a common-garden experimental protocol implemented over an 8-year period, we show that embryos of farmed salmon and multigenerational farmed–wild hybrids (F1, F2, wild backcrosses) had slower developmental rates than those of two regional wild populations. In certain cases, our data suggest that hybrid developmental rates are sufficiently mismatched to prevailing environmental conditions that they would have reduced survival in the wild. This implies that repeated farmed–wild interbreeding could adversely affect wild populations. Our results therefore reaffirm previous recommendations that based on the precautionary principle, improved strategies are needed to prevent, or to substantially minimize, escapes of aquaculture fishes into wild environments.

scholarly journals Phenotypic plasticity of labile traits in the wild

2013 ◽  
Vol 59 (4) ◽  
pp. 485-505 ◽  
Author(s):  
Jon E. Brommer
Keyword(s):  
Life History ◽  
Phenotypic Plasticity ◽  
Statistical Approach ◽  
Scale Up ◽  
Population Level ◽  
Wild Populations ◽  
Quantitative Genetic ◽  
In The Wild ◽  
The Individual ◽  
Quantitative Genetic Parameters

Abstract Individual-based studies allow quantification of phenotypic plasticity in behavioural, life-history and other labile traits. The study of phenotypic plasticity in the wild can shed new light on the ultimate objectives (1) whether plasticity itself can evolve or is constrained by its genetic architecture, and (2) whether plasticity is associated to other traits, including fitness (selection). I describe the main statistical approach for how repeated records of individuals and a description of the environment (E) allow quantification of variation in plasticity across individuals (IxE) and genotypes (GxE) in wild populations. Based on a literature review of life-history and behavioural studies on plasticity in the wild, I discuss the present state of the two objectives listed above. Few studies have quantified GxE of labile traits in wild populations, and it is likely that power to detect statistically significant GxE is lacking. Apart from the issue of whether it is heritable, plasticity tends to correlate with average trait expression (not fully supported by the few genetic estimates available) and may thus be evolutionary constrained in this way. Individual-specific estimates of plasticity tend to be related to other traits of the individual (including fitness), but these analyses may be anti-conservative because they predominantly concern stats-on-stats. Despite the increased interest in plasticity in wild populations, the putative lack of power to detect GxE in such populations hinders achieving general insights. I discuss possible steps to invigorate the field by moving away from simply testing for presence of GxE to analyses that ‘scale up’ to population level processes and by the development of new behavioural theory to identify quantitative genetic parameters which can be estimated.

An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

scholarly journals Documentation of multiple species of marine fish trapped in Atlantic salmon sea-cages in Norway

2018 ◽  
Vol 31 ◽  
pp. 31
Author(s):  
Per Gunnar Fjelldal ◽  
Monica F. Solberg ◽  
Kevin A. Glover ◽  
Ole Folkedal ◽  
Jonatan Nilsson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Trutta ◽  
Gadus Morhua ◽  
Mesh Size ◽  
Anguilla Anguilla ◽  
Wild Fish ◽  
Melanogrammus Aeglefinus ◽  
European Eel ◽  
Farmed Salmon ◽  
Sea Trout

The production of salmonids in sea-cages has been developed for monoculture of the target species. However, we show here for the first time, that wild fish may enter sea-cages used for farming of Atlantic salmon (Salmo salar L.) in Norway, out-grow the mesh size, and thereafter become permanently trapped. Within seven different sea-cages located in western Norway, eight different species of wild fish were identified; European eel (Anguilla anguilla), sea trout (Salmo trutta L.), cod (Gadus morhua), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), pollack (Pollachius pollachius), hake (Merluccius merluccius) and whiting (Merlangius merlangus). In the two most extreme cases, a 5 × 5 × 7 m cage with 311 farmed salmon (903 g) also contained 542 whiting (79 g), 77 haddock (43 g), and 5 cod (26 g), and a 12 × 12 × 15 m cage with 1695 farmed salmon (559 g) also contained 1196 haddock (35 g), 1115 whiting (31 g), 46 cod (23 g), 23 saithe (48 g), 15 pollock (22 g), 5 sea trout (54 g), and 2 hake (29 g). The present study thus demonstrates that aquaculture cages designed for monoculture may attract and effectively ‘trap’ wild fish. We did not investigate the frequency of this occurrence, and the ecological significance of these observations remains unclear. However, with the ever-increasing number of sea-cages used for global aquaculture, this is clearly a topic for further research.

scholarly journals Negligible risk of zoonotic anisakid nematodes in farmed fish from European mariculture, 2016 to 2018

2021 ◽  
Vol 26 (2) ◽  
Author(s):  
Maria Letizia Fioravanti ◽  
Andrea Gustinelli ◽  
George Rigos ◽  
Kurt Buchmann ◽  
Monica Caffara ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Transmission Risk ◽  
Fish Parasites ◽  
Gilthead Seabream ◽  
Farmed Fish ◽  
Eu Regulation ◽  
Zoonotic Risk ◽  
Freezing Treatment ◽  
Zoonotic Parasites ◽  
Anisakid Larvae

Background The increasing demand for raw or undercooked fish products, supplied by both aquaculture and fisheries, raises concerns about the transmission risk to humans of zoonotic fish parasites. This has led to the current European Union (EU) Regulation No 1276/2011 amending Annex III of Regulation (EC) No 853/2004 and mandating a freezing treatment of such products. Zoonotic parasites, particularly anisakid larvae, have been well documented in wild fish. Data on their presence in European aquaculture products, however, are still scarce, except for Atlantic salmon (Salmo salar), where the zoonotic risk was assessed as negligible, exempting it from freezing treatment. Aim To evaluate the zoonotic Anisakidae parasite risk in European farmed marine fish other than Atlantic salmon. Methods From 2016 to 2018 an observational parasitological survey was undertaken on 6,549 farmed fish including 2,753 gilthead seabream (Sparus aurata), 2,761 European seabass (Dicentrarchus labrax) and 1,035 turbot (Scophthalmus maximus) from 14 farms in Italy, Spain and Greece. Furthermore, 200 rainbow trout (Oncorhynchus mykiss) sea-caged in Denmark, as well as 352 seabream and 290 seabass imported in Italy and Spain from other countries were examined. Fish were subjected to visual inspection and candling. Fresh visceral organs/fillet samples were artificially digested or UV pressed and visually examined for zoonotic anisakid larvae. Results No zoonotic parasites were found in any of the fish investigated. Conclusions The risk linked to zoonotic Anisakidae in the examined fish species from European mariculture appears negligible. This study laid the groundwork for considerations to amend the current EU regulation.

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