Stress-related changes in the metabolic rate of juvenile spotted grunter, Pomadasys commersonnii (Haemulidae, Pisces)

Abstract

Metabolic responses were measured in juvenile spotted grunters subjected to stress factors pertinent to handling and transportation. The metabolic response to chase and capture lasted ~15 min during which period oxygen consumption rate increased from 0.26 mg to 0.62 mg O₂ g^–1 h^–1. Routine metabolism was re-established after ~90 min. An acute increase in temperature resulted in significant increase in oxygen consumption, with a rapid rise from 0.25 to 0.36 mg O₂ g^–1 h^–1 before settling at a rate of 0.30 mg O₂ g^–1 h^–1. The oxygen consumption of individual fish was not affected by the presence of their conspecifics or by high fish density within the range tested. It is concluded that, although an acute increase in temperature results in considerable stress in this species, the greatest stress is caused during chase-and-capture, whereas packing density within the range tested in this study does not cause stress.