Metabolic rates of juvenile scalloped hammerhead sharks (Sphyrna lewini)

Abstract.

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 O₂ kg^–1 h^–1 at 21°C and 203 mg O₂ kg^–1 h^–1 at 29°C (mean±SD: 189±15 mg O₂ kg^–1 h^–1 at 26°C). Total metabolic rates ranged from 275 mg O₂ 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 O₂ 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.