| 1. |
- Aas, O., et al.
(författare)
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Salmonid stocking in five North Atlantic jurisdictions: Identifying drivers and barriers to policy change
- 2018
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Ingår i: Aquatic Conservation-Marine and Freshwater Ecosystems. - : Wiley. - 1052-7613. ; 28:6, s. 1451-1464
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Tidskriftsartikel (refereegranskat)abstract
- New knowledge challenges long-established practices of fish stocking and transfer because of increasing scientific consensus that the release of cultivated fish can pose risks to biodiversity; however, stocking can also improve fisheries, creating difficult decision trade-offs regarding its use. Accordingly, controversy persists about fish stocking and transfer. No studies, however, have embraced a multinational perspective to understand the important governance dimensions of the success and failure of salmonid stocking and transfer policies. The present study has analysed the historical development and contemporary governance of the stocking and transfer of native and non-native salmonids of the genera Salmo, Salvelinus, and Oncorhynchus in five legislative units around the North Atlantic Ocean: the Atlantic Provinces of Canada, France, Germany, Norway, and Sweden. The study is based on the analyses of published and unpublished literature, and a survey of experts. Current salmonid stocking policies and practices varied significantly among jurisdictions; the degree of policy change varied, from radical and rapid changes de jure and de facto in Atlantic Canada and Norway to incremental mostly de jure changes in France and Germany. Rapid policy change in Atlantic Canada, Norway, and partly in Sweden can be explained by the socio-political importance of salmonid fisheries, stocking regulations based on policy objectives to conserve wild Atlantic salmon (Salmo salar), well-documented examples of the harmful consequences of transfers of non-native species, and well-developed vertical governance linkages. The policy changes resemble that of the 'punctuated equilibrium policy framework'. By contrast, France and Germany place less socio-political emphasis on salmonids, have stocking regulations less directed at wild salmonids, more local-level decision making, more species-rich fish communities, and little evidence of adverse ecological impacts of the transfer and stocking of salmonids. This has led to small, incremental changes in stocking policy de facto that are reflective of the 'advocacy coalition policy framework'.
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| 2. |
- Cucherousset, J., et al.
(författare)
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Growth-enhanced salmon modify stream ecosystem functioning
- 2021
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 99:6, s. 1978-1989
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Tidskriftsartikel (refereegranskat)abstract
- Use of fast-growing domesticated and/or genetically modified strains of fish is becoming increasingly common in aquaculture, increasing the likelihood of deliberate or accidental introductions into the wild. To date, their ecological impacts on ecosystems remain to be quantified. Here, using a controlled phenotype manipulation by implanting growth hormone in juvenile Atlantic salmon (Salmo salar), we found that growth-enhanced fish display changes in several phenotypic traits known to be important for ecosystem functioning, such as habitat use, morphology and excretion rate. Furthermore, these phenotypic changes were associated with significant impacts on the invertebrate community and key stream ecosystem functions such as primary production and leaf-litter decomposition. These findings provide novel evidence that introductions of growth-enhanced fish into the wild can affect the functioning of natural ecosystems and represent a form of intraspecific invasion. Consequently, environmental impact assessments of growth-enhanced organisms need to explicitly consider ecosystem-level effects.
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| 3. |
- Devlin, R. H., et al.
(författare)
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Assessing Phenotypic and Ecological Effects of Transgenic Fish Prior to Entry into Nature.
- 2007
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Ingår i: Kapuscinski, A.R., K.R. Hayes, S. Li and G. Dana (eds). (E.M. Hallerman and P.J. Schei, series editors). 2007. Environmental Risk Assessment of Genetically Modified Organisms, Vol 3: Methodologies for Transgenic Fish. - Cambridge, MA, USA : CABI. - 9781845932961 ; , s. 151-187
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Neregård, Lena, 1973, et al.
(författare)
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Wild Atlantic salmon Salmo salar L. strains have greater growth potential than a domesticated strain selected for fast growth
- 2008
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Ingår i: Journal of Fish Biology. - : Wiley. - 1095-8649 .- 0022-1112. ; 73:1, s. 79-95
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Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to examine the responses of three Atlantic salmon Salmo salar strains to growth hormone (GH) treatment. A positive growth response to sustained-release GH implants was found in two wild strains (Namsen and Imsa) as well as one domesticated strain (AquaGen). The data revealed that the growth-selected AquaGen strain has further growth potential, however, a stronger growth response was observed in the wild strains which outgrew the domesticated strain after GH treatment. These observations suggest that some growth potential may have been lost during the selection for rapid growth in the AquaGen strain. In September, the parr were GH implanted and in December sampled for plasma GH and insulin-like growth factor I (IGF-I) levels, liver, muscle and gill GH receptor, IGF-I mRNA levels, gill Na+,K+-ATPase activity, muscle and liver lipid content and body silvering. Low temperature and seasonal growth cessation probably explains the relatively limited GH effects found. Body silvering in all strains was positively correlated to size. GH increased IGF-I plasma levels in the Namsen strain inspite of liver IGF-I mRNA levels being lower in GH-treated fish.
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| 5. |
- Rosengren, Malin, 1982, et al.
(författare)
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Born to be wild: effects of rearing density and environmental enrichment on stress, welfare, and smolt migration in hatchery-reared Atlantic salmon
- 2017
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 74:3, s. 396-405
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Tidskriftsartikel (refereegranskat)abstract
- Hatchery-reared salmonids released into the wild generally have poor survivability compared with wild conspecifics. To assess potential hatchery rearing improvements, behavioral and physiological effects of reducing animal density and adding in-tank shelter were investigated. Atlantic salmon (Salmo salar) parr were placed in barren or shelter-enriched tanks at high or low density up until release as smolts. Lowered density rendered positive effects on growth and intestinal barrier function, and both lowered density and shelter decreased conspecific aggression, as inferred by fin damage. Furthermore, while the presence of shelter decreased stress hormone levels following human disturbance, it also decreased growth and smolt migration success, an effect particularly pronounced at high densities. Therefore, we suggest that this type of structural enrichment should be avoided for Atlantic salmon smolts held at high densities and conclude that a lowered animal density with or without shelter has the highest potential in producing a more resilient smolt for stocking.
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| 6. |
- Rosengren, Malin, 1982, et al.
(författare)
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High risk no gain-metabolic performance of hatchery reared Atlantic salmon smolts, effects of nest emergence time, hypoxia avoidance behaviour and size
- 2017
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Ingår i: Physiology & Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 175, s. 104-112
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Tidskriftsartikel (refereegranskat)abstract
- When animals are reared for conservational releases it is paramount to avoid reducing genetic and phenotypic variation over time. This requires an understanding of how diverging behavioural and physiological traits affect performance both in captivity and after release. In Atlantic salmon, emergence time from the spawning gravel has been linked to certain behavioural and physiological characteristics and to the concept of stress coping styles. Early emerging fry has for example been shown to be bolder and more aggressive and to have higher standard metabolic rates compared to late emerging fry. The first aim was therefore to examine if emergence latency affect the behavioural stress coping response also beyond the fry and parr stage. This was done using a hypoxia avoidance test, where an active behavioural avoidance response can be related to higher risk taking. No behavioural differences were found between the two emergence fractions either at the parr or pre-smolt stage, instead smaller individuals were more prone to express an "active" hypoxia avoidance response. Further, an individual expressing a "passive" response as parr were also more prone to express this behaviour at the pre-smolt stage. While there are some previous studies showing that early emerging individuals with a bolder personality may be favored within a hatchery setting it is not known to what extent these early differences persist to affect performance after release. The second aim was therefore to compare the physiological performance at the time of release as smolts using the two subgroups; 1) early emerging fish showing active hypoxia avoidance (Early + Bold) and 2) late emerging fish showing a passive hypoxia response (Late + Shy). The Early + Bold group showed a higher red blood cell swelling, suggesting a higher adrenergic output during stress, whereas there was no difference in post-stress plasma cortisol or physiological smolt status. While there was no difference in standard metabolic rate between the groups, the Early + Bold group exhibited a lower maximum metabolic rate and aerobic scope following strenuous swimming. In captivity this may have no clear negative effects, but in the wild, a more risk prone behavioural profile linked to a lower aerobic capacity to escape from e.g. a predator attack, could clearly be disadvantageous.
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| 7. |
- Sundt-Hansen, L., et al.
(författare)
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Growth hormone reduces growth in free-living Atlantic salmon fry
- 2012
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463. ; 26:4, s. 904-911
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Tidskriftsartikel (refereegranskat)abstract
- 1. Although life-history theory predicts that juvenile growth rates should be high, there is substantial evidence that most juveniles grow below their physiological maximum. The endocrine system plays an important role in the determination of fundamental life-history traits, and hormones often serve as a link between an organisms environment and the expression of a trait. Particularly, growth is a life-history trait, which is strongly associated with growth hormone (GH) in fish, as well as most vertebrates. 2. To elucidate trade-offs related to elevated GH in fish in a natural environment, we experimentally administrated GH exogenously to juvenile Atlantic salmon using sustained-release GH implants, at an earlier ontogenetic stage than previously achieved (1.5 months). We assessed the effects on growth, dispersal and survival in contrasting environments. 3. Exogenous GH treatment increased the growth rate when fish were fed ad libitum in captivity. However, in a natural stream, GH treatment had a significant negative effect on growth and no apparent effect on survival or dispersal. This contrasts with previous studies conducted at later developmental stages, which show either a positive growth effect or no effect of elevated GH levels. 4. This study shows that environmental conditions strongly affect the response to GH and that under some natural conditions, it may also reduce growth. We suggest that the endogenous plasma GH levels may be maximizing growth during early, but not later, juvenile stages in nature.
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| 8. |
- Adriaenssens, Bart, 1979, et al.
(författare)
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Natural selection, plasticity, and the emergence of a behavioural syndrome in the wild
- 2013
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 16:1, s. 47-55
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Tidskriftsartikel (refereegranskat)abstract
- Individuals often show consistent behavioural differences where behaviours can form integrated units across functionally different contexts. However, the factors causing and maintaining behavioural syndromes in natural populations remain poorly understood. In this study, we provide evidence for the emergence of a behavioural syndrome during the first months of life in wild brown trout (Salmo trutta). Behavioural traits of trout were scored before and after a 2-month interval covering a major survival bottleneck, whereupon the consistency and covariance of behaviours were analysed. We found that selection favoured individuals with high activity levels in an open-field context, a personality trait consistent throughout the duration of the experiment. In addition, a behavioural syndrome emerged over the 2 months in the wild, linking activity to aggressiveness and exploration tendency. These novel results suggest that behavioural syndromes can emerge rapidly in nature from interaction between natural selection and behavioural plasticity affecting single behaviours.
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| 9. |
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| 10. |
- Adriaenssens, Bart, 1979, et al.
(författare)
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Shy trout grow faster: exploring links between personality and fitness-related traits in the wild.
- 2011
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Ingår i: Behavioral Ecology. - 1045-2249. ; 22:1, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- In many animals, individual differences in behavior show remarkable consistency across situations and contexts (i.e., animal personality and behavioral syndromes). Studies on the association between personality traits and fitness-related measures in nature are, however, important to clarify the causes and consequences of this phenomenon. Here, we tested for correlations between 3 behavioral axes in brown trout (Salmo trutta) parr: exploration tendency, behavioral flexibility, and aggressiveness. Next, we tested how these individual behaviors relate to social dominance and performance under natural conditions (growth, survival, and movement). We found support for behavioral syndromes in brown trout with less explorative individuals being less aggressive and showing more flexible behavior. In addition, these low-explorative personality types grew faster than bolder conspecifics in the wild. Standardized aggression in the laboratory was a poor indicator of social dominance, and neither of these 2 traits affected performance in the wild. These results challenge the view that personality traits can be predicted by constant associations with life-history trade-offs (e.g., boldness is linked with rapid growth). Moreover, our findings suggest that fitness predictions from laboratory measures of behavior should be made with caution and ideally tested in nature.
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