The effect of ploidy and incubation temperature on survival and the prevalence of aplasia of the septum transversum in Atlantic salmon, Salmo salar L

Abstract

Heart deformities are a concern in aquaculture and are linked to egg incubation temperature. Diploid and triploid Atlantic salmon, Salmo salar L., were incubated at 6, 8 and 10 °C and analysed for aplasia of the septum transversum (n = 150 ploidy⁻¹ incubation temperature⁻¹). Heart morphology (size and shape) was assessed in fish incubated at 6 °C and in fish with and without aplasia of the septum transversum (n = 9 group⁻¹) incubated at 10 °C. Egg mortality was significantly higher in triploids than in diploids at all incubation temperatures, and increased egg incubation temperatures increased mortality in both ploidy. Triploids grew quicker than diploids after egg incubation at 10 °C, but not at 6 °C. Aplasia of the septum transversum occurred only in triploid fish after incubation at 6 °C and 8 °C (0.7% and 3.3%, respectively) and was significantly greater (P ≤ 0.05) in triploids after incubation at 10 °C compared with diploids (30% and 18%, respectively). Aplasia of the septum transversum significantly increased heart mass and resulted in a long flat ventricle compared with fish displaying a septum transversum. The results suggest triploid salmon should be incubated below 8 °C.

Fast water currents reduce production performance of post-smolt Atlantic salmon Salmo salar

“…(2). Images of the caudal surface of the heart ventricle were used to determine the roundness of the ventricle according to Fraser et al (2014).…”

Aplasia of the septum transversum has no effect on plasma biochemistry following an acute hypoxic event in Atlantic salmon

“…Aplasia of the septum transversum (AST) had no effect on any plasma parameter in comparison to fish with a septum transversum (Septum) weaker and more liable to rupture, but this would need to be confirmed by histological examination that was not undertaken in the present study. Nevertheless, AST had no effect on body size similar to results in parr (Fraser et al 2014), suggesting that this condition does not impede growth. AST results in major alterations to heart morphology, but there was no effect of this condition on any plasma parameter following hypoxia.…”

“…In the current study, 28% of the fish had AST in comparison to only 18% in the same population at the parr stage (Fraser et al 2014). If this condition results in a significant increase in mortality risk to the fish, one would expect this value to be lower over time as the only known risk factor for AST is high incubation temperature (Ørnsrud et al 2004(Ørnsrud et al , Takle et al 2005.…”

“…The study population was described by Fraser et al (2014), but only diploid fish incubated at 10°C were used in the current study. Briefly, Atlantic salmon ova and milt were provided by Aquagen (Trondheim, Norway), and the present experiment was carried out at the Institute of Marine Research, Matre Research Station, Norway.…”

“…Specifically, the malformation results in a heart ventricle that has a flattened rounded appearance ( Fig. 1; see Fraser et al 2014 for a morphological description) that is in contrast to the pyramidal shape that is known to optimise cardiac performance in salmonids (Claireaux et al 2005). Based on the latter, one would expect fish with AST to have a reduced cardiac output that would limit oxygen (O 2 ) delivery to the body during periods of high cardiac demand.…”