Fig. 7
Average heart rate (fH in bpm) values in free-swimming Atlantic salmon held at 8 °C for 6 weeks following surgical implantation of centi-HRT ACT or milli-HRT tags. Open symbols represent day-time measurements, whereas dark symbols represent periods of night-time. a A segmented regression was fitted to the day-time and night-time fH data, and the equations and break-points for these regressions were: fH1 = − 0.44 * day + 39.75, fH2 = 0.016 * (day − 21.75) + 30.17; break-point 21.75 days; and fH1 = − 0.54 * day + 34.13, fH2 = − 0.01 * (day − 17.12) + 24.89; break-point 17.12 days. b Results from the linear mixed-effects model: a lower case ‘a’ indicates a significant difference from the final week of recovery (W6) (b) with night-time values in bold. The asterisk (*) indicates values that were significantly different between day-time and night-time values. Data are means ± S.E.M, with each value representing the average of 6 data points per fish (n = 5)