OXYGEN-CONSUMPTION RATES OF MIDWATER FISHES AS A FUNCTION OF DEPTH OF OCCURRENCE

Oxygen consumption was measured in 23 pelagic fish species whose minimum dept of occureence ranged from zero to 1,000 m. Weight-specific respiratory rate declined rapidly with increasing minimum depth of occureence. The decrease is partially due to environmental and compositional factors that covary with depth. Decreasing temperature accounts for 2% and the increased water content of deeper living species accounts for 30% of the observed decline. Other factors that might contribute to the decreasing oxygen consumption rate either had no significant effect (size, ash-free dry weight) or were considered to have small effects on the basis of existing evidence (pressure). The unexplained remainder of the decline appears to be an inherent characteristics of deeper living species that may be thought of as a decrease in aerobic metabolism per unit of muscle. © 1979.