Metabolic rates of juvenile scalloped hammerhead sharks (Sphyrna lewini)

Oxygen consumption of juvenile scalloped hammerhead sharks, Sphyrna lewini, was measured in a Brett-type flume (volume = 635 l) to quantify metabolic rates over a range of aerobic swimming speeds and water temperatures. Oxygen consumption (log transformed) increased at a linear rate with increases in tailbeat frequency and swimming speed. Estimates of standard metabolic rate ranged between 161 mg O-2 kg(-1) h(-1) at 21 degreesC and 203 mg O-2 kg(-1) h(-1) at 29 degreesC (mean SD: 189 +/- 15 mg O-2 kg(-1) h(-1) at 26 degreesC). Total metabolic rates ranged from 275 Mg O-2 kg(-1) h(-1) at swimming speeds of 0.5 body lengths per second (L s(-1)) to a maximum aerobic metabolic rate of 501 Mg O-2 kg(-1) h(-1) at 1.4 L s(-1). Net cost of transport was highest at slower swimming speeds (0.5-0.6 L s(-1)) and was lowest between 0.75 and 0.9 L s(-1). Therefore, these sharks are most energy efficient at swimming speeds between 0.75 and 0.9 L s(-1). These data indicate that tailbeat frequency and swimming speed can be used as predictors of metabolic rate of free-swimming juvenile hammerhead sharks.