Relationships between heart rate and metabolic rate of pike: integration of existing data

Abstract

The percentage contribution of heart rate (fH) to change in oxygen consumption (V o2) was examined in relation to body weight and across the metabolic scope of pike. Also the consequences of variability around the regression relating V o2 and fH for estimating V o2 were considered. The percentage contribution of fH was calculated using two equations, one that ignored and one that included an estimate for oxygen consumed by the gills and absorbed across the skin (V o2s). Using both equations the percentage contribution of fH calculated using maximum and resting values for fH and V o2 decreased with weight of pike. The omission of V o2s, resulted in erroneously high estimates of the percentage contribution of fH for pike of any given weight. The omission of V o2s resulted in erroneously high estimates of the percentage contribution of fH over the region of the metabolic scope where fH is related linearly to V o2, whereas the equation that included V o2s resulted in the expected value of 100%. Assuming zero experimental error and under normoxic conditions, the 95% confidence limits for single estimates of V o2 from 30–60‐min readings of heart rate are ±39% at a heart rate of 30 beats min −1. Averaged over longer periods the error decreases, and used over several days to estimate meal size the error is of the order of 1%.