Fig. 1. Time course of respirometry in a bluefin tuna. Oxygen consumption (_O2, filled circles) was calculated from the slope of ambient [O₂] measured during 10 min periods with the swim tunnel sealed. An overnight acclimation period preceded tests of swim speed (blue line, in BL s^–1) and temperature (black line) effects on _O2. The arrow during the acclimation period indicates elevated _O2 measurements following a power surge, which startled the fish. Speed changes are described elsewhere (Blank et al., 2007) and were not a part of the present study.