The spatial scale of density-dependent growth and implications for dispersal from nests in juvenile Atlantic salmon

We investigated habitat use of Atlantic salmon (Salmo salar) parr in experimental riverine enclosures made up of pool, riffle, and run habitats over a range of densities (0.1-1.25 fish·m-2) to test the implicit assumption in habitat modelling that habitat selection does not change with population density. Results indicated that habitat use changed with population density, with relatively more parr in pools and fewer in runs at higher population densities. Temperature influenced parr distribution, with relatively more parr in runs and fewer in riffles and pools at higher temperatures. Parr distribution was primarily affected by hydromorphological differences among pool, riffle, and run habitats. Effects of population density and temperature on use of pool, riffle, and run habitats were often as large as effects of hydromorphological differences among pool, riffle, and run habitats on fish distributions over the range of temperatures and densities observed. Results varied considerably, despite controlled experimental conditions. We concluded that habitat selection by juvenile Atlantic salmon parr may be density dependent and potentially quite variable.

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Density-dependent growth of young-of-the-year Atlantic salmon (Salmo salar) revisited

Ecology Of Freshwater Fish ◽

10.1111/j.1600-0633.2009.00394.x ◽

2010 ◽

Vol 19 (1) ◽

pp. 1-6 ◽

Cited By ~ 27

Author(s):

I. Imre ◽

J. W. A. Grant ◽

R. A. Cunjak

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Density Dependent ◽

Atlantic Salmon Salmo Salar ◽

Young Of The Year ◽

Dependent Growth

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Density-dependent growth of young-of-the-year Atlantic salmon Salmo salar in Catamaran Brook, New Brunswick

Journal of Animal Ecology ◽

10.1111/j.1365-2656.2005.00949.x ◽

2005 ◽

Vol 74 (3) ◽

pp. 508-516 ◽

Cited By ~ 130

Author(s):

I. IMRE ◽

J. W. A. GRANT ◽

R. A. CUNJAK

Keyword(s):

Atlantic Salmon ◽

New Brunswick ◽

Salmo Salar ◽

Density Dependent ◽

Atlantic Salmon Salmo Salar ◽

Young Of The Year ◽

Dependent Growth

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Are wild populations ideally distributed? Variations in density-dependent habitat use by age class in juvenile Atlantic salmon (Salmo salar)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f08-087 ◽

2008 ◽

Vol 65 (8) ◽

pp. 1667-1680 ◽

Cited By ~ 25

Author(s):

A. Jamie F. Gibson ◽

Heather D. Bowlby ◽

Peter G. Amiro

Keyword(s):

Atlantic Salmon ◽

Habitat Use ◽

Salmo Salar ◽

Habitat Quality ◽

Normal Function ◽

Age Classes ◽

Density Dependent ◽

Atlantic Salmon Salmo Salar ◽

Juvenile Atlantic Salmon ◽

Habitat Gradient

We examined relationships between abundance and habitat use in three age classes of juvenile Atlantic salmon ( Salmo salar ) in the Stewiacke River, Nova Scotia, Canada. Using stream gradient as a proxy for habitat quality, we used a double half normal function, modified to include density dependence, to model the relationship between habitat quality and fish density. We found that density was asymmetrically distributed around a similar optimum gradient for all three age classes regardless of abundance. Habitat use was highly density-dependent for age-0 and age-1 juveniles, but not for age-2+ salmon. As abundance of age-0 and age-1 salmon increased, their relative density decreased in low-gradient habitat and increased in higher-gradient habitat, although their absolute density increased in all stream gradient categories. Variation in habitat use was consistent with ideal free theory for age-1 juveniles in high-gradient habitat, but not in low-gradient habitat. Age-2+ individuals appeared not to modify their distribution among habitats, even though increasing competition changes the relative benefit of low-gradient habitat in terms of resource acquisition. In contrast, age-1 individuals responded to increased competition by modifying their distribution along the habitat gradient, even though this may have slightly reduced an individual’s potential for growth.

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Dispersal and density-dependent growth of Atlantic salmon (Salmo salar) juveniles: clumped versus dispersed stocking

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2015-0488 ◽

2017 ◽

Vol 74 (9) ◽

pp. 1337-1347 ◽

Cited By ~ 8

Author(s):

Eric Blake Brunsdon ◽

Dylan John Fraser ◽

William Rundle Ardren ◽

James William Angus Grant

Keyword(s):

Growth Rate ◽

Atlantic Salmon ◽

Salmo Salar ◽

Negative Power ◽

Growth And Survival ◽

Density Dependent ◽

Atlantic Salmon Salmo Salar ◽

Nesting Sites ◽

Juvenile Habitat ◽

Dependent Growth

Dispersal from nesting sites and habitat selection are essential for the fitness of young individuals and shape the distribution, growth, and persistence of populations. These processes are important to consider when releasing young, hatchery-origin fishes into the wild to restore extirpated or depleted populations. By manipulating the density of released young-of-the-year (YOY) Atlantic salmon (Salmo salar), we evaluated the effects of clumped- (releasing all the fish at one location) and dispersed-stocking (releasing the fish evenly over a complete reach) treatments on juvenile habitat use, dispersal, growth, and survival. Across 14 river reaches, clump-stocked YOY density decreased and growth rate increased with distance downstream, whereas dispersed-stocked YOY densities and growth were relatively constant. Overall, density, spatial variance in density, growth, and survival did not differ between these two stocking treatments, likely due to the greater-than-expected mobility of fish in clumped-stocking reaches; YOY dispersed up to 1600 m, with 41% moving over 200 m downstream. As predicted from previous work, growth rate of individual fish was density-dependent, following a negative power curve. Our results provide insights into how the growth and survival of released individuals are altered via stocking treatments, ultimately shaping their distribution and growth rate.

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