Effect of acclimation temperature on the upper thermal tolerance of Colorado River cutthroat trout Oncorhynchus clarkii pleuriticus: thermal limits of a North American salmonid

Abstract

In an effort to explore the thermal limitations of Colorado River cutthroat trout Oncorhynchus clarkii pleuriticus, the critical thermal maxima (T(cmax) ) of 1+ year Lake Nanita strain O. c. pleuriticus were evaluated when acclimated to 10, 15 and 20° C. The mean ±s.d.T(cmax) for O. c. pleuriticus acclimated to 10° C was 24·6 ± 2·0°C (n = 30), for 15° C-acclimated fish was 26·9 ± 1·5° C (n = 23) and for 20° C-acclimated fish was 29·4 ± 1·1° C (n = 28); these results showed a marked thermal acclimation effect (Q₁₀ = 1·20). Interestingly, there was a size effect within treatments, wherein the T(cmax) of larger fish was significantly lower than that of smaller fish acclimated to the same temperature. The critical thermal tolerances of age 0 year O. c. pleuriticus were also evaluated from three separate populations: Lake Nanita, Trapper Creek and Carr Creek reared under 'common-garden' conditions prior to thermal acclimation. The Trapper Creek population had significantly warmer T(cmax) than the Lake Nanita population, but that of the Carr Creek fish had T(cmax) similar to both Trapper Creek and Lake Nanita fish. A comparison of these O. c. pleuriticus T(cmax) results with those of other stream-dwelling salmonids suggested that O. c. pleuriticus are less resistant to rapid thermal fluctuations when acclimated to cold temperatures, but can tolerate similar temperatures when acclimated to warmer temperatures.

Variation in temperature tolerance among families of Atlantic salmon (Salmo salar) is associated with hypoxia tolerance, ventricle size and myoglobin level

“…Here, CT max ranged from a low of 22.3°C to a high of 27.5°C. High CT max variability was also observed in cutthroat trout, Oncorhynchus clarkii (Underwood et al, 2012), with tolerance varying 8°C among individuals as compared with 5.2°C here. However, in cutthroat trout the size of the fish varied, which explained some of the phenotypic variation found, as CT max correlated significantly and negatively with the size of the fish.…”

Optimum and maximum temperatures of sockeye salmon (Oncorhynchus nerka) populations hatched at different temperatures

“…2). Since incubation temperature affects fish size at hatch (Ojanguren and Braña 2003) and body size can affect temperature tolerance (Underwood et al 2012), a second set of CTmax determinations was performed when each population had attained a common mean body mass of ϳ1 g (0.89 ± 0.03 to 1.23 ± 0.04 g; n = 19-20 per population), which was achieved with age varying from 135 to 214 days posthatch depending on population and incubation temperature. High mortality occurred within most populations for egg incubation at 16°C, therefore CTmax was determined for only four populations at 90 days posthatch and none were measured at ϳ1 g (Table 1).…”

Critical thermal maxima of juvenile alligator gar (Atractosteus spatula, Lacépède, 1803) from three Mississippi-drainage populations acclimated to three temperatures

“…Underwood et al. () found greater CT Max in cutthroat trout Oncorhynchus clarkii collected from low elevations compared to those collected in high elevations. Brook trout Salvelinus fontinalis strains from different hatcheries have also been demonstrated to have differing CT Max albeit using a modified technique (McDermid et al., ).…”