Effect of incubation temperature on growth performance in Atlantic salmon

Abstract

Interspecific variations in thermal growth performance of ectotherms have received considerable recent interest fueled by the focus on ecological climate change effects. Amongpopulation variations in growth are commonly observed in field studies. However, the role of pheno typic plasticity in shaping this variation is largely unexplored in teleost fishes. Here, we tested for the effect of incubation temperature on thermal scaling of growth and maximum growth performance of the anadromous salmonid Atlantic salmon Salmo salar L. Salmon eggs were incubated and reared until the onset of exogenous feeding at either heated or natural temperatures or transferred from natural to heated temperatures at the time of hatching, creating 3 different embryonic temperature treatments (heated, natural or mixed). We subsequently tested for juvenile growth performance of these groups at 8 temperatures ranging from 6 to 24°C. Maximum growth was significantly higher in the heated than the natural and mixed incubation temperature groups, but we did not observe differences in the thermal scaling of growth performance. Neither the upper nor lower thermal limit for growth nor the optimal growth temperature differed be tween the 3 incubation temperature treatments. However, thermal conditions experienced by in cubating embryos affected later growth performance. Although similar results have been observed previously among reptiles, this is to our knowledge the first empirical support for this hypothesis among teleost fishes. Phenotypic plasticity in growth performance can likely explain many of the contrasting findings from previous research on countergradient growth effects in teleost fishes.

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

“…Their short migration distance enables them to have energy to conceive bigger eggs (Crossin et al 2004), which can then compensate for higher incubation temperature. Indeed, others have previously shown that a large yolk mass can buffer against untoward effects of elevated incubation temperature on survival and growth of hatchlings (Beacham and Murray 1985;Ojanguren and Braña 2003;Finstad and Jonsson 2012). We suggest a similar buffering effect on CTmax, a proposition that needs to be experimentally tested but one certainly supported by the significant correlation between egg mass and CTmax demonstrated here, which was independent of incubation temperature.…”

“…Besides the intraspecific differences of hatchling size, increasing incubation temperature reduces fry mass (here and previously, e.g., Beacham and Murray 1985;Ojanguren and Braña 2003;Finstad and Jonsson 2012), likely because of a reduced aerobic scope and capacity for growth (Pörtner 2010). Reduced fry size, however, correlated negatively with CTmax, explaining some of the population variation in CTmax.…”

“…Elevated temperature during egg incubation can also cause skeletal abnormality (Dionísio et al 2012), pericardial edema (Kurokawa et al 2008), irregular myofibrillar growth (Albokhadaim et al 2007), and poor swimming performance (Burgess et al 2006). Moreover, increased incubation temperature leads to small hatchlings (Ojanguren and Braña 2003;Finstad and Jonsson 2012), possibly because routine metabolic rate and energy consumption increase exponentially with temperature, thus, leading to reduced capacity for growth and development at temperature beyond the optimum (Pörtner 2010). Although the effects of incubation temperature on fish embryogenesis are well studied (Murray and McPhail 1988;Damme et al 1992;Mueter et al 2002;Burt et al 2012;Lahnsteiner et al 2012), little is known in terms of how incubation temperature affects the posthatch temperature tolerance of fish and whether or not population differences exist.…”

Linking embryonic temperature with adult reproductive investment in Atlantic salmon Salmo salar

“…(Quinn et al 2004(Quinn et al , 2011. Our results indicate that it may not be early growth per se, but elevated incubation temperature that increased juvenile growth (Finstad & Jonsson 2012), which is associated with a larger egg size. In the present study, we found no effect of juvenile growth on egg size when the effect of thermal embryonic conditions and adult size were controlled for.…”

“…Finstad & Jonsson (2012) showed that contrary to larval development, warm water during embryogenesis stimulated juvenile growth of salmon. To our knowledge, no study other than ours has demonstrated that thermal conditions experienced by embryos before hatching affect their adult body size.…”