Remote monitoring of heart rate as a measure of recovery in angled Atlantic salmon, Salmo salar (L.)

The introduction of ‘Catch and Release’ fishery programs are now widely employed by fisheries managers in most Atlantic Provinces, primarily due to the recent decline of Atlantic salmon stocks on the east coast of Canada. However, there is still considerable debate among special interest groups and regulators as to the effectiveness of the technique. Heart rate telemetry has been utilized as a tool for the assessment of metabolic rate in wild fish by a number of investigators, and was employed in the present study in order to assess recovery following staged angling events in Atlantic salmon. Wild Atlantic salmon were successfully angled at 20 ±2 °C and 16.5 ±1 °C at Noel Paul's Brook, Newfoundland. In addition, hatchery reared Atlantic salmon were angled at the Ontario Ministry of Agriculture and Fisheries Research Station, Alma, Ontario, at a temperature of 8 ±1 °C. Survival rate for the angled salmon was 20% at 20 ± 2 °C; 100± at 16.5 ±1 °C; and 100% at 8 ± 1 °C. Mean resting heart rate for the fish angled at 16.5 °C and 20 ° C was approximately 1.6 and 1.8 times greater than that of fish angled at 8 °C. Heart rate, post angling, was found to increase 1.2 fold in the 8 °C group, 1.3 fold in the 16.5 °C group and approximately 1.15 fold in the 20 °C group. Time to recovery was assessed as a return to observed resting heart rate for each individual fish and was found to be similar for both the 8 °C and 16.5 °C angled groups (approximately 16 h). Although heart rate telemetry in fish is, perhaps, not an ideal measure of metabolic rate, the present study has demonstrated that remote monitoring of heart rate is a good indicator of post exercise physiological activity.