Estimated Respiration Rate of Myctophid Fish from the Enzyme Activity of the Electron-transport-system

Abstract

Whole animal respiration rates (R) of myctophid fishes which migrate up to the surface at night were estimated using enzyme activities of the electrontransport-system (ETS). The fish, currently unsusceptible to laboratory experimentation, were caught at sea and stored frozen at-20°C for 14-17 days prior to enzyme assay. Supplemental tests on two tropical marine fishes (gobies and pomacentrids) showed no measurable loss of ETS activity during storage for up to 36 d at-20°C. The ETS/R ratio for gobies and pomacentrids was 1.61. Respiration rates of myctophid fishes estimated using this ETS/R ratio ranged from 17.7 to 453μl O₂ individual^-1 hr^-1 for specimens weighing between 26-1101 mg wet weight atin situtemperature of 24-27°C. The relationship between the respiration rate standardized to a temperature of 20°C (R:μl O₂ individual^-1hr^-1) and wet weight (WW: mg) of myctophid fishes was expressed as R=0.790 WW^0.84 (r=0.964, n=27). This relationship does not differ appreciably from the respiration rates of other marine fishes calculated from Winberg's equation.