Mechanisms underlying the increase in young-of-the-year Atlantic salmon (Salmo salar) density with habitat complexity

Venter, Oscar; Grant, James W. A.; Nöel, Mary-Hélène; Kim, Jaewoo

doi:10.1139/f08-106

Cited by 41 publications

(54 citation statements)

References 40 publications

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“…One possible explanation for this could be that refuging increases prey density, thereby increasing levels of resource competition, which itself has been demonstrated to increase the strength of NCEs [45,46]. However, other studies suggest that increasing habitat complexity and reducing the visual field of salmon fry result in increased local densities [47,48] due to reduced territorial behaviour [49,50]. Recently, it was shown that smaller territory sizes do not result in differences in growth rate due to limited foraging opportunities in salmon fry [51,52].…”

Section: Discussionmentioning

confidence: 99%

Nonconsumptive Effects of Predation and Impaired Chemosensory Risk Assessment on an Aquatic Prey Species

Elvidge

Brown

2015

International Journal of Ecology

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Weak levels of acidity impair chemosensory risk assessment by aquatic species which may result in increased predator mortalities in the absence of compensatory avoidance mechanisms. Using replicate populations of wild juvenile Atlantic salmon (Salmo salar) in neutral and acidic streams, we conducted a series of observational studies and experiments to identify differences in behaviours that may compensate for the loss of chemosensory information on predation risk. Comparing the behavioural strategies of fish between neutral and acidic streams may elucidate the influence of environmental degradation on nonconsumptive effects (NCEs) of predation. Salmon in acidic streams are more active during the day than their counterparts in neutral streams, and are more likely to avoid occupying territories offering fewer physical refugia from predators. Captive cross-population transplant experiments indicate that at equal densities, salmon in acidic streams do not demonstrate relative decreases in growth rate as a result of their different behavioural strategies. Instead, altering diel activity patterns to maximize visual information use and occupying relatively safer territories appear sufficient to offset increased predation risk in acidic streams. Additional strategies such as elevated foraging rates during active periods or adopting riskier foraging tactics are necessary to account for the observed similarities in growth rates.

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Section: Discussionmentioning

confidence: 99%

Nonconsumptive Effects of Predation and Impaired Chemosensory Risk Assessment on an Aquatic Prey Species

Elvidge

Brown

2015

International Journal of Ecology

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“…Heggenes et al (1999) found that small trout (<7 cm) were abundant in shallow areas with water velocities ranging from 10 to 50 cm 3 Ás À1 , while larger trout (>7 cm) were found in deeper and more slowflowing habitats. Shelter or cover is related to the substrate composition (Finstad et al 2007;Venter et al 2008), and survival has been connected to access to shelter and cover for salmonids (Chapman 1966;Hunt 1976;Marschall & Crowder 1995;Finstad et al 2007). In our study, trout has a higher variation in habitat choice dependent on species, density and fish size.…”

Section: Discussionmentioning

confidence: 99%

Selective segregation in intraspecific competition between juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)

Berg

Bremset

Puffer

et al. 2013

Ecology of Freshwater Fish

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Interactive segregation has been suggested as the ruling competition mechanism determining niche and niche segregation between juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Results from allopatry-sympatry observations of habitat use in both nature and in experiments were contrary to predictions derived from the interactive segregation hypothesis. Habitat use parameters under natural conditions such as distance to shore for Atlantic salmon parr were nearly identical in allopatric (mean AE SD; 3.2 AE 1.4 m) and sympatric (3.3 AE 1.4 m) situations. Occupied water depths largely reflected available water, but water depths <15 cm were avoided by salmon parr. Under experimental conditions, habitat use of allopatric salmon was density independent and salmon size had only minor effects, with smaller fish being more likely to occur in the shallow. Habitat use of salmon in sympatry with trout did not differ from allopatric salmon habitat use, and only salmon size had minor effects on depth choice -occurrence of trout or fish density had no effect. Allopatric trout was in general more frequent in the shallow habitat than salmon. Habitat use of sympatric trout was affected by the occurrence of salmon and trout size, resulting in a higher use of the shallow habitats for small trout. To conclude, selective segregation has a dominant role in salmon habitat use (not affected by trout occurrence), whereas a mixed situation occurs in trout habitat use with elements of interactive segregation when competing with Atlantic salmon (affected by salmon occurrence).

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“…Hydraulic conditions specially affect territory area and foraging behaviour, since it is directly linked to the availability, distribution and composition of drifting prey (Reid and Thoms, 2008). Territory area typically decreases as habitat quality and complexity (Imre et al, 2002;Dolinsek et al, 2007;Venter et al, 2008), or food abundance (Keeley, 2000) increase. Moreover, biotic factors such as competition with introduced species can modify aggression and foraging behaviour in fish populations (Seiler and Keeley, 2007).…”

Section: Discussionmentioning

confidence: 99%

Modelling brown trout spatial requirements through physical habitat simulations

Ayllón

Almodóvar

Nicola

et al. 2010

River Research & Apps

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Territorial behaviour is often considered the main mechanism regulating salmonid populations and territory size regarded as the proximate factor that limits abundance, being mainly determined by body size. Despite the spatial requirements of young-of-theyear (YOY) brown trout, Salmo trutta, have been previously established, there is still a gap in the knowledge about the spatial needs of older individuals. Therefore, we aimed to develop an allometric territory size relationship for YOY, juvenile and adult trout. Territory size was inferred from 12-year demographic data and physical habitat simulations performed at 10 pristine sites where populations showed high and stable densities. When compared to previous models in salmonids, results revealed not only interspecific but also intraspecific significant differences in the size of territories used by individuals of comparable size. Interestingly, the explanatory power of the derived allometric territory size relationships was similar to previous models based on individual observational data. It suggested that despite the fact that results obtained from population data cannot explicitly describe territorial behaviour of individuals, they may represent accurately their spatial requirements. Finally, results suggested that territory volume, and not territory area, scaled with body size at a rate consistent with brown trout metabolic rate, the scaling rate being highly constant at any level of simulated proportion of nonterritorial fish in the population. Consequently, if individuals must increase territories to fulfil energetic demands, the allometry of territory volume seems a better predictor of spatial requirements than territory area.

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Mechanisms underlying the increase in young-of-the-year Atlantic salmon (Salmo salar) density with habitat complexity

Cited by 41 publications

References 40 publications

Nonconsumptive Effects of Predation and Impaired Chemosensory Risk Assessment on an Aquatic Prey Species

Nonconsumptive Effects of Predation and Impaired Chemosensory Risk Assessment on an Aquatic Prey Species

Selective segregation in intraspecific competition between juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)

Modelling brown trout spatial requirements through physical habitat simulations

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