Effect of acclimation temperature on routine metabolic rate in triploid salmonids.

The objective of this research was to determine whether triploid fish differ from diploids in their routine metabolic rates across a range of acclimation temperatures. Sibling diploids and triploids were acclimated to 12, 15 and 18 degrees C (Atlantic salmon; Salmo salar) and to 9, 12 and 15 degrees C (brook charr; Salvelinus fontinalis) prior to experimentation. Routine metabolic rates were then determined three times over a two-month period. Triploids of both species had higher metabolic rates than diploids at lower temperatures, and lower metabolic rates than diploids at higher temperatures, demonstrating that triploids have different (i.e., lower) thermal optima than diploids. This likely explains prior observations of high mortality of triploids at chronically elevated, but sub-lethal, rearing temperatures for sibling diploids.