| 1. |
- 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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| 2. |
- 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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| 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. |
- Höjesjö, Johan, 1967, et al.
(författare)
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Rapid bystander assessment of intrinsic fighting ability: behavioural and heart rate responses in rainbow trout
- 2007
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472. ; 74:16, s. 1743-1751
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Tidskriftsartikel (refereegranskat)abstract
- The ability of bystanders to assess the intrinsic fighting ability of potential opponents with and without contest information was examined in an experimental study using rainbow trout, Oncorhynchus mykiss. Behavioural and heart rate responses were monitored for bystanders observing size-matched conspecifics before and after a staged contest with an opponent. The results suggest that bystanders can rapidly and accurately assess the intrinsic fighting ability/quality of a potential opponent. Within 10 s, bystanders increased their visual exposure towards opponents subsequently becoming subordinate and decreased their exposure towards opponents becoming dominant. Male bystanders showed higher visual exposure towards opponents than did females, regardless of the sex of the opponent. This immediate behavioural response was subsequently (24 h after the first exposure) followed by elevated heart rate in bystanders exposed to dominant opponents, probably reflecting a physiological stress response. Apparently, bystanders used reliable size-independent cues allowing a rapid behavioural response. The delayed physiological response probably arises from the chemical cues associated with the presence of a dominant opponent, or a combination of initial visual cues and subsequent continuous exposure to chemical cues. The results suggest that bystanders are able to rapidly assess the intrinsic fighting ability of a similar-sized potential opponent without information about its contest success against other individuals. This ability can be utilised by bystanders to withdraw from costly contest with low winning probability. Thus, escalated conflicts may be less common in nature than previously suggested by laboratory studies.
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| 5. |
- Johnsson, Jörgen I, 1959, et al.
(författare)
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Predation risk and the territory value of cover: an experimental study
- 2004
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 56:4, s. 388-392
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Tidskriftsartikel (refereegranskat)abstract
- In an experiment on territorial brown trout (Salmo trutta), we addressed the novel hypothesis that protective cover increases the value of a territory in relation to the perceived level of predation risk. We predicted that territory holders should invest more resources defending territories with cover than territories without cover, and that defence should increase as predation risk increases. First, trout were allowed to establish ownership in territories with or without overhead cover. Second, predation risk was manipulated by simulating aerial predator attacks in half of the territories of each type, whereupon the preference for cover was estimated. Third, owners of the four types of territories were staged in dyadic contests against size-matched intruders. Territory owners showed a preference for cover, which increased further after simulated predator attacks. In subsequent contests, conflicts over territories with cover were settled faster than conflicts over territories without cover, which may suggest that the value of cover increases the motivational asymmetry between owner and intruder. Consistent with our hypothesis, owners of territories with cover were much more aggressive if they had been subjected to predator attacks the day before the conflict. These results suggest that territory owners are able to estimate the value of protective cover in response to variation in the level of predation risk in the habitat.
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| 6. |
- Johnsson, Jörgen I, 1959, et al.
(författare)
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Social interactions
- 2006
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Ingår i: Behaviour and Physiology of Fish , Fish Physiology, Vol. 24. Eds. K. Sloman, R. Wilson and S. Balshine. (Series Eds. A.P. Farrell, and C.P. Brauner). - San Diego, CA, USA : Academic Press. - 9780123504487 ; , s. 151-196
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Landeira-Dabarca, A., et al.
(författare)
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Cue recognition and behavioural responses in the three-spined stickleback (Gasterosteus aculeatus) under risk of fish predation
- 2019
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Ingår i: Acta Ethologica. - : Springer Science and Business Media LLC. - 0873-9749 .- 1437-9546. ; 22:3, s. 209-221
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Tidskriftsartikel (refereegranskat)abstract
- To effectively respond to predation risk, prey must assess the risk associated with different predation cues. Predation cues can stem either from the predator or from conspecifics and indicate different predation risk levels, thus eliciting different anti-predation responses. The three-spined stickleback is a well-studied fish species often found in gregarious formations. Previous studies show that sticklebacks perform a variety of anti-predation behaviours; however, little is known about how they respond to multiple simultaneous predator cues, characteristic of heterogeneous natural habitats. Here, we experimentally compare the relative importance of three types of predation cues (visual predator cue, chemical predator odour cue and chemical alarm cue from injured conspecifics) and their interactions, on anti-predation and foraging behaviour of sticklebacks. Results showed that (1) individual sticklebacks responded most strongly to visual predator cues, which resulted in reduced foraging activity, increased spine erection and increased predator inspection; (2) the presence of chemical cues (predator odour and/or conspecific alarm cues) stimulates freezing behaviour to a minor extent; and (3) anti-predation behaviour manifests as a trade-off with foraging-related activities. Overall, the results indicate that sticklebacks could assess risk and modify their behavioural responses depending on which cues are present in the environment. The experimental approach of using factorial combinations of different predatory cues can increase our understanding of the role of multimodal cues in aquatic ecosystems.
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| 8. |
- Larsen, M. H., et al.
(författare)
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Effects of Emergence Time and Early Social Rearing Environment on Behaviour of Atlantic Salmon: Consequences for Juvenile Fitness and Smolt Migration
- 2015
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Consistent individual differences in behaviour have been well documented in a variety of animal taxa, but surprisingly little is known about the fitness and life-history consequences of such individual variation. In wild salmonids, the timing of fry emergence from gravel spawning nests has been suggested to be coupled with individual behavioural traits. Here, we further investigate the link between timing of spawning nest emergence and behaviour of Atlantic salmon (Salmo salar), test effects of social rearing environment on behavioural traits in fish with different emergence times, and assess whether behavioural traits measured in the laboratory predict growth, survival, and migration status in the wild. Atlantic salmon fry were sorted with respect to emergence time from artificial spawning nest into three groups: early, intermediate, and late. These emergence groups were hatchery-reared separately or in co-culture for four months to test effects of social rearing environment on behavioural traits. Twenty fish from each of the six treatment groups were then subjected to three individual-based behavioural tests: basal locomotor activity, boldness, and escape response. Following behavioural characterization, the fish were released into a near-natural experimental stream. Results showed differences in escape behaviour between emergence groups in a net restraining test, but the social rearing environment did not affect individual behavioural expression. Emergence time and social environment had no significant effects on survival, growth, and migration status in the stream, although migration propensity was 1.4 to 1.9 times higher for early emerging individuals that were reared separately. In addition, despite individuals showing considerable variation in behaviour across treatment groups, this was not translated into differences in growth, survival, and migration status. Hence, our study adds to the view that fitness (i.e., growth and survival) and life-history predictions from laboratory measures of behaviour should be made with caution and ideally tested in nature.
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| 9. |
- 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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| 10. |
- Sundström, L. Fredrik, 1972, et al.
(författare)
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Feeding on profitable and unprofitable prey: Comparing behaviour of growth-enhanced transgenic and normal coho salmon (Oncorhynchus kisutch)
- 2004
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 110:5, s. 381-396
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Tidskriftsartikel (refereegranskat)abstract
- We compared the performance of normal and growth hormone-transgenic coho salmon feeding on surface drifting edible and inedible novel prey items in various social environments. With an inherently higher appetite, we predicted that transgenic fish would be more willing to feed on novel prey, and that visual company with another fish would enhance this difference further. Transgenic and normal fish, of similar size and age, were equally willing to attack both the edible (live insects) and inedible (artificial angling lure flies) prey, but transgenic fish did so faster and were more likely to make repeated attacks. Transgenic fish managed to seize and consume the edible prey after fewer attacks than did normal fish. However, swallowing of prey took longer than for normal fish. More transgenic individuals interacted with the inedible prey compared with normal salmon, and initially, transgenic fish in visual company with another fish also interacted more with the prey than single transgenic or any constellation of normal focal fish. With repeated exposures, the number of individuals attacking and the number of interactions with the prey decreased. These responses were stronger in transgenic fish, partly explained by the initially low response in normal fish. The observed differences are most likely the consequences of elevated levels of growth hormone in transgenic fish generating enhanced feeding motivation and reinforcement capacity. In a natural environment, the performance of a growth hormone-transgenic fish may therefore depend on the relative abundance of profitable vs. unprofitable prey, as well as the presence of other transgenic individuals.
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