Evaluation of Two Types of Anesthesia for Performing Surgery on Striped Bass

Abstract

Tricaine (MS-222) is the most widely used anesthetic for fishes, but induction and recovery times are rather long. Studies on salmonids have shown that electroanesthesia is a good alternative to MS-222 for short term (<1 min) immobilization. However, data on longer-duration (3–5-min) immobilization needed for surgical procedures are lacking. We analyzed induction and recovery times for 20 adult (52–81-cm) striped bass Morone saxatilis immobilized with electroanesthesia and MS-222. We defined induction time as the interval from the onset of each treatment until the fish was immobilized (i.e., did not respond to tactile stimuli) and recovery time as the interval from the fish's return to the water to its resumption of normal swimming. Surgical procedures similar to those necessary to implant a radio transmitter were performed on each fish. Induction time for fish immobilized with electroanesthesia (geometric mean, 8 s; 95% confidence interval [CI], 3–21 s) was much shorter than that for fish immobilized with MS-222 (geometric mean, 47 s; 95% CI, 38–58 s) (P = 0.0006). Additionally, fish immobilized with electroanesthesia recovered much faster (geometric mean, 9 s; 95% CI, 4–19 s) than fish immobilized with MS-222 (geometric mean, 206 s; 95% CI, 156–272 s) (P ⩽ 0.0001). Faster induction and recovery times of fish immobilized with electroanesthesia and the ability to process more fish per unit time are major benefits of this technique.