Thermal performance of juvenile Atlantic Salmon,Salmo salarL.

Abstract

Summary 1.Experimental data for maximum growth and food consumption of Atlantic Salmon ( Salmo salar L.) parr from five Norwegian rivers situated between 59 and 70 ° N were analysed and modelled. The growth and feeding models were also applied to groups of Atlantic Salmon growing and feeding at rates below the maximum. The data were fitted to the Ratkowsky model, originally developed for bacterial growth. 2. The rates of growth and food consumption varied significantly among populations but the variation appeared unrelated to thermal conditions in the river of population origins. No correlation was found between the thermal conditions and limits for growth, thermal growth optima or maximum growth, and hypotheses of population-specific thermal adaptation were not supported. Estimated optimum temperatures for growth were between 16 and 20 ° C. 3. Model parameter estimates differed among growth-groups in that maximum growth and the performance breadth decreased from fast to slow growing individuals. The optimum temperature for growth did not change with growth rate. 4. The model for food consumption (expressed in energy terms) peaked at 19-21 ° C, which is only slightly higher than the optimal temperature for growth. Growth appeared directly related to food consumption. Consumption was initiated ≈ 2 ° C below the lower temperature for growth and terminated ≈ 1·5 ° C above the upper critical temperature for growth. Model parameter estimates for consumption differed among growth-groups in a manner similar to the growth models. 5. By combining the growth and consumption models, growth efficiencies were estimated. The maximum efficiencies were high, 42-58%, and higher in rivers offering hostile than benign feeding and growth opportunities.

Atlantic salmon show capability for cardiac acclimation to warm temperatures

“…Such selection may have been relaxed for Atlantic salmon. Consistent with the present study, but on a smaller geographic scale, Norwegian Atlantic salmon populations are known to share similar optimum and critical growth temperatures despite differences in habitat temperatures 18 . Similarly, Arctic char (Salvelinus alpinus) populations from Inari, Finland (70°N), and Windermere, UK (54°N), have similar upper incipient lethal temperatures of B23°C 19 .…”

Effect of incubation temperature on growth performance in Atlantic salmon

“…Fish that died during the experiment (19 out of 480) were replaced by similarly sized fish to maintain densities at 10 fish per tank, but the replacement fish were not included in the results. The setup of the growth performance experiments followed a well-documented and standardized protocol (Jonsson et al 2001, Finstad et al 2004, Larsson et al 2005, Forseth et al 2009). Mean mass (± SD) of the fish at start of the first growth experiment run was 6.2 ± 1.2, 9.0 ± 1.4, and 12.1 ± 2.2 g for natural, mixed and heated incubation temperatures, respectively, and 9.4 ± 2.4, 11.6 ± 2.5, and 14.7 ± 3.1 g for the second.…”

“…On the other hand, recent experimental studies have not supported either of the first 2 hypotheses , Jonsson et al 2001, Larsson et al 2005, but leave the third possibility open. Circumstantial support for the third hypothesis was also given by a 25 yr long monitoring of the production of the anadromus salmonid Atlantic salmon Salmo salar L. in the River Imsa, Norway.…”

Differential changes in growth patterns of anadromous brown trout and Atlantic salmon from the River Etneelva over a 25-year period

“…Such factors may be competition for food, either due to high fish densities or to variable food availability (Jonsson & Jonsson 2009b). In an experimental study, maximum growth of Atlantic salmon parr from the River Suldalslågen, located close to the River Etneelva, was found at 168C (Jonsson et al 2001). In brown trout parr, the maximum growth rate was found at 13.98C (Elliott & Hurley 2000), while at 19.58C growth of brown trout parr may be equal to zero (Elliott 1975).…”