Dispersal and density-dependent growth of early juvenile Atlantic salmon (Salmo salar): Can density manipulations via stocking technique improve restoration?

• Main Author: Brunsdon, Eric
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: Atlantic salmon; Salmo salar
• Online Access: https://spectrum.library.concordia.ca/id/eprint/980486/; https://spectrum.library.concordia.ca/id/eprint/980486/1/Brunsdon_MSc_F2015.pdf

Dispersal from nesting sites and habitat selection are essential for the fitness of young individuals and shapes the distribution, growth and persistence of populations. These processes are important to consider when releasing captive bred young individuals into the wild to restore extirpated or depleted populations. However, few studies have evaluated how manipulating densities during release affects the dispersal and growth of individuals with respect to crucial life history traits. I manipulated the density of young-of-the-year (YOY) Atlantic salmon to evaluate the effect of two stocking techniques on the life history characteristics of surviving fish. Salmon were either point-stocked (all fish released in a small area at the upstream end of a reach) or spread-stocked (fish were released evenly over the entire reach) in 14 reaches of the Boquet River, New York. I used snorkeling and electrofishing surveys to characterize the density, dispersal, growth and survival of salmon stocked via each technique. Density decreased and growth rate increased with distance downstream in point-stocking reaches, whereas density and growth were relatively constant within spread-stocking reaches. Overall, density, growth and survival did not differ between the two stocking techniques due to the greater-than-expected degree of dispersal observed in point-stocking reaches. YOY dispersed up to 1600m, with 41% moving over 200m downstream. Growth rate of individual fish was density-dependent, following the negative power curve observed in previous studies. My results provide insights into how the growth and survival of released individuals are altered via stocking techniques, ultimately shaping their distribution and persistence.