Oxygen and carbon dioxide transport during sustained exercise in diploid and triploid chinook salmon (Oncorhynchus tshawytscha)

Abstract

To better understand the respiratory physiology of triploid fish, we conducted an analysis of O2and CO2transport in diploid and triploid chinook salmon (Oncorhynchus tshawytscha) swimming at 0.4 body lengths (BL)·s–1, at 2.0 BL·s–1, and at the critical swimming velocity (Ucrit). While O2consumption rates (MO2), MO2max, and Ucrit did not differ between ploidies, triploids had a smaller increase in MO2over the course of the swimming trial and lower arterial O2content (CaO2) values than diploids. Relative to diploids, triploids swimming at Ucrit had a reduced Hb–O2saturation, lower red blood cell (RBC) pH, but similar O2partial pressures (PaO2) and methemoglobin values. Overall, triploids and diploids did not differ in CaCO2, PaCO2, arterial pH, or lactate at any of the swimming speeds. Taken together, triploidy does not appear to impair CO2transport or acid–base balance during sustained exercise in chinook salmon. In contrast, our results show that triploids have a smaller O2carrying capacity than diploids. While triploids may be able to compensate for their reduced aerobic capacity under the current exercise regime, we suggest that the effects of triploidy on O2transport may contribute to the inferior performance of triploid salmon when reared under suboptimal conditions.