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

2010 ◽  
Vol 19 (1) ◽  
pp. 1-6 ◽  
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

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

2017 ◽  
Vol 74 (9) ◽  
pp. 1337-1347 ◽  
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.

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

2008 ◽  
Vol 65 (9) ◽  
pp. 1956-1964 ◽  
Author(s):  
Oscar Venter ◽  
James W.A. Grant ◽  
Michelle V. Noël ◽  
Jae-woo Kim
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Habitat Complexity ◽  
Indirect Evidence ◽  
Growth Potential ◽  
Territory Size ◽  
Complex Environments ◽  
Atlantic Salmon Salmo Salar ◽  
Direct Support ◽  
Young Of The Year

We tested three hypotheses used to explain the increase in young-of-the-year (YOY) Atlantic salmon ( Salmo salar ) density with habitat complexity: the territory-size, predator-refuge, and foraging-benefits hypotheses. We manipulated habitat complexity in three different treatments (boulder-removed, control, and boulder-added) at eight sites in Catamaran Brook and the Little Southwest Miramichi River, New Brunswick. The density of juvenile salmon was two times higher in the boulder-added treatment than in the other treatments. Our data were consistent with the territory-size hypothesis; visual isolation was highest and territory size was smallest in the boulder-added treatment, and salmon selected microhabitats to maximize their field of view. Our results showed partial support for the predator-refuge hypothesis; salmon in the boulder-added sites were closer to cover and showed a reduced reaction distance to a novel stimulus, but did not preferentially select microhabitats closer to cover. We found no direct support for the foraging-benefits hypothesis; however, there is indirect evidence that boulders may improve the growth potential of instream habitat. Our results suggest that YOY Atlantic salmon may be attracted to complex environments for the increased cover and that the decreased visibility of these sites causes a reduction in territory size, allowing a higher density of fish.

Patterns and correlates of movement and site fidelity in individually tagged young-of-the-year Atlantic salmon (Salmo salar)

2003 ◽  
Vol 60 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Stefán Ó Steingrímsson ◽  
James W.A Grant
Keyword(s):  
Atlantic Salmon ◽  
Habitat Use ◽  
Salmo Salar ◽  
Site Fidelity ◽  
Population Regulation ◽  
Fish Movement ◽  
Population Densities ◽  
Atlantic Salmon Salmo Salar ◽  
Young Of The Year ◽  
Study Sites

The literature on stream fish movement offers diverse views on the patterns (restricted vs. nonrestricted), causes (competition vs. habitat use), and consequences (mobile fish of lower vs. equal fitness) of movement. We tagged 320 young-of-the-year Atlantic salmon (Salmo salar) (30.1–55.3 mm), using relatively noninvasive tagging (elastomers) and recovery (snorkeling) techniques, to test these alternative views. Most fish (mean = 63.8%) stayed in the study sites (10–120 m) throughout their respective study season (28–74 days). Of the resighted fish, 61.8% moved less than 1 m up- or down-stream and only three fish moved more than 10 m, causing extremely leptokurtic movement curves. Movement and site fidelity were weakly affected by habitat use and competition. Fish originally found in slow water moved farther than fish from fast water, whereas fish found at high population densities were more likely to disappear than fish from low densities. Finally, mobile fish grew as fast or faster than more sedentary fish, supporting the idea that movement can be advantageous and is not just a by-product of density-dependent population regulation.

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