Electron transport system(ETS) activity as a possible index of respiration for larval walleye pollock Theragra chalcogramma.

Abstract

Electron transport system (ETS) activity was measured for larvae of the walleye pollock Theragra chalcogramma, with the objective of assessing this method for estimating the respiration of fish larvae in situ. The ETS activity decreased minimally after 50 days' storage at -80°C. The ETS activity increased linearly with larval dry weight. The average dry weight-specific ETS activity of feeding stage larvae was 9.75±2.25 (S.D.) μlO2/mg•h, which was significantly higher than 5.82±0.88μlO2/mg•h for pre-feeding stage larvae. The average ratio of respiration to ETS activity was 0.47±0.16. As in laboratory raised larvae, the ETS activity in wild larvae also increased linearly with larval dry weight. The regression coefficient of laboratory raised and wild larvae were not significantly different. The average dry weight-specific ETS activity for wild larvae was 8.60±2.99μlO2/mg•h. The comparison of the ETS activity in laboratory raise and wild larvae indicates that the ETS activity method has potential to assess respiratory activity of pollock larvae in situ. Further experiments are needed to evaluate the impact of various environmental conditions to the respiration to ETS activity ratio, which is necessary to convert ETS activity data to respiration.