Swimming performance and associated ionic disturbance of juvenile pink salmon Oncorhynchus gorbuscha determined using different acceleration profiles

Swimming performance was assessed in juvenile pink salmon Oncorhynchus gorbuscha (body mass <5·0 g) using five different protocols: four constant acceleration tests each with a different acceleration profile (rates of 0·005, 0·011, 0·021 and 0·053 cm s −2 ) and a repeated ramped‐critical swimming speed test. Regardless of the swim protocol, the final swimming speeds did not differ significantly ( P > 0·05) among swim tests and ranged from 4·54 to 5·20 body lengths s −1 . This result supports the hypothesis that at an early life stage, O. gorbuscha display the same fatigue speeds independent of the swimming test utilized. Whole body and plasma [Na + ] and [Cl − ] measured at the conclusion of these tests were significantly elevated when compared with control values ( P < 0·05) and appear to be predominantly associated with dehydration rather than net ion gain. Given this finding for a small salmonid, estimates of swim performance can be accurately measured with acceleration tests lasting <10 min, allowing a more rapid processing than is possible with a longer critical swim speed test.