Effect of Dummy Telemetry Transmitters on Stamina of Atlantic Salmon (Salmo salar) Smolts

Abstract

Effects of three different-sized, internally placed dummy ultrasonic transmitters and one size externally placed dummy radio transmitter on swimming performance of Atlantic salmon (Salmo salar) smolts were determined. Critical swimming speeds were similar for fish in control groups and two of the groups tagged with internal transmitters. The widest internal dummy tag (19 mm long × 10 mm diameter) caused a significant (P < 0.05) decrement in swimming performance; the size representing the smallest available transmitters (33 mm long × 8 mm diameter) did not. Linear regression analysis of this latter group demonstrated that larger smolts carried the transmitter better than smaller smolts. Results indicated that fish longer than about 20 cm can successfully be tagged with the available transmitter. Externally placed dummy radio transmitters caused a highly significant (P < 0.01) decrease in swimming speed compared with that of controls.