Predation risk breaks size-dependent dominance in juvenile coho salmon (<i>Oncorhynchus kisutch</i>) and provides growth opportunities for risk-prone individuals

Reinhardt, Ulrich G.

doi:10.1139/f99-064

Cited by 43 publications

(26 citation statements)

References 25 publications

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“…[28]). The T MT strain containing the OnMTGH1 construct has been used for all simulated stream studies examining ecological effects of GH transgenic coho salmon (e.g.…”

Section: Discussionmentioning

confidence: 99%

Growth-Enhanced Transgenic Coho Salmon (Oncorhynchus kisutch) Strains Have Varied Success in Simulated Streams: Implications for Risk Assessment

et al. 2017

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Growth hormone (GH) transgenic fish have accelerated growth and could improve production efficiency in aquaculture. However, concern exists regarding potential environmental risks of GH transgenic fish should they escape rearing facilities. While environmental effects have been examined in some GH transgenic models, there is a lack of information on whether effects differ among different constructs or strains of transgenic fish. We compared growth and survival of wild-type coho salmon (Oncorhynchus kisutch) fry, a fast-growing GH transgenic strain containing a metallothionein promoter (TMT), and three lines/strains containing a reportedly weaker histone-3 promoter (TH3) in hatchery conditions and semi-natural stream tanks with varying levels of natural food and predators. Rank order of genotype size and survival differed with varying environmental conditions, both within and among experiments. Despite accelerated growth in hatchery conditions, TMT fry gained little or no growth enhancement in stream conditions, had enhanced survival when food was limiting, and inconsistent survival under other conditions. Rank growth was inconsistent in TH3 strains, with one strain having highest, and two strains having the lowest growth in stream conditions, although all TH3 strains had consistently poor survival. These studies demonstrate the importance of determining risk estimates for each unique transgenic model independent of other models.

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“…[28]). The T MT strain containing the OnMTGH1 construct has been used for all simulated stream studies examining ecological effects of GH transgenic coho salmon (e.g.…”

Section: Discussionmentioning

confidence: 99%

Growth-Enhanced Transgenic Coho Salmon (Oncorhynchus kisutch) Strains Have Varied Success in Simulated Streams: Implications for Risk Assessment

et al. 2017

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“…Stream tanks generally omit predators. Reinhardt (1999) found that the intensity of agonistic encounters occurring among coho salmon, were affected by predation risk. An increase in simulated predation risk, using an electrified model of a kingfisher, reduced agonistic encounters and allowed smaller fish better access to feeding positions.…”

Section: Increased Social and Environmental Complexitymentioning

confidence: 99%

“…Therefore, the absence of predators may exaggerate physiological variation associated with dominance. Pronounced positive correlations between dominance and growth and dominance and length disappeared when predators were added (Reinhardt, 1999). Structural complexity may influence social interactions.…”

Section: Increased Social and Environmental Complexitymentioning

confidence: 99%

Physiological effects of dominance hierarchies: laboratory artefacts or natural phenomena?

Sloman

Armstrong

2002

Journal of Fish Biology

192

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Studies of fish behaviour have demonstrated the existence of social interactions that result in dominance hierarchies. In environments in which resources, such as food, shelter and mates, are limited, social competition results in some fish becoming dominant and occupying the most profitable positions. This behaviour has been observed in natural environments and also in many laboratory-based experiments. When two fish have been confined in a small tank, one of them usually has exhibited behaviour that suggests it is dominant over the other submissive animal. Physiological consequences of social interaction can be seen in both dominants and subordinates but are more extreme in the subordinate. However, this scenario is without doubt an artificial situation. Fewer experiments have been conducted using laboratory experiments that are more socially and physically complex than those experienced by dyads in tanks. In simple fluvial tanks, through which water is recirculated, the physiological responses of fish to social competition have generally been qualitatively similar to those recorded among dyads. However, when environmental disturbances, complex resource distributions, increase in water flushing, presence of predators and competing species of fish have been included in experimental designs, there have been fewer, diminished or no physiological differences between dominant and subordinate fish. There have been very few studies of physiology in relation to dominance in natural habitats, and those that have been conducted suggest that under some circumstances hierarchies may cause less intense physiological responses than have been suggested based on results of laboratory studies in simple environments. Possible reasons for these variations are discussed. The need is identified for a well structured experimental approach to the investigation of the causes and consequences of hierarchies if the ecology of wild fish is to be modelled effectively based on physiological processes. It is also suggested that the further development and application of techniques for monitoring physiologies of fish in the wild is important.

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“…It is possible that growth requirements of age I+ coho and steelhead differ, and that age I+ coho accept a slower growth rate in exchange for less predation risk because they will smolt early the following summer. This has been suggested for coho (Reinhardt 1999) and clearly demonstrated for Atlantic salmon (Thorpe et al 1992;Metcalfe 1998;Juanes et al 2000). If this is the case it would be an example of selective segregation based on long-term survival, rather than on short-term energetic, considerations.…”

Section: Discussionmentioning

confidence: 77%

Development of net energy intake models for drift-feeding juvenile coho salmon and steelhead

2008

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We developed models to predict the effect of water velocity on prey capture rates and on optimal foraging velocities of two sympatric juvenile salmonids, coho salmon and steelhead. Mean fish size was 80 mm, the size of age I+ coho and steelhead during their second summer in Southeast Alaska streams, when size overlap suggests that competition might be strongest. We used experimentally determined prey capture probabilities to estimate the effect of water velocity on gross energy intake rates, and we modeled prey capture costs using experimental data for search and handling times and published models of swimming costs. We used the difference between gross energy intake and prey capture costs to predict velocities at which each species maximized net energy intake rate. Predicted prey capture rates for both species declined from~75 to 30-40 prey/h with a velocity increase from 0.30 to 0.60 m·s −1 . We found little difference between coho and steelhead in predicted optimum foraging velocities (0.29 m·s −1 for coho and 0.30 m·s −1 for steelhead). Although prey capture ability appears to be more important than are prey capture costs in determining optimum foraging velocities, capture costs may be important for models that predict fish growth. Because coho are assumed to pay a greater swimming cost due to a less hydrodynamic body form, we also modeled 10 and 25% increases in hydrodynamic drag to assess the effect of increased prey capture costs. This reduced optimum velocity by 0 and 0.01 m•s −1 , respectively. Habitat segregation among equal-sized coho and steelhead does not appear to be related to the effects of water velocity on their respective foraging abilities.

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Predation risk breaks size-dependent dominance in juvenile coho salmon (Oncorhynchus kisutch) and provides growth opportunities for risk-prone individuals

Cited by 43 publications

References 25 publications

Growth-Enhanced Transgenic Coho Salmon (Oncorhynchus kisutch) Strains Have Varied Success in Simulated Streams: Implications for Risk Assessment

Growth-Enhanced Transgenic Coho Salmon (Oncorhynchus kisutch) Strains Have Varied Success in Simulated Streams: Implications for Risk Assessment

Physiological effects of dominance hierarchies: laboratory artefacts or natural phenomena?

Development of net energy intake models for drift-feeding juvenile coho salmon and steelhead

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