A Local Analgesic, Lidocaine, Did Not Affect Short‐Term Welfare During Electroanesthesia of a Teleost Fish

In recent decades, fisheries research has benefited from the use of various forms of electroimmobilization to facilitate fish handling through rapid induction and recovery times, capacity to allow immediate release, and other advantages not shared by pharmaceuticals. However, as electroimmobilization becomes increasingly prevalent, it is expected that animal care committees may require electroimmobilized fish to also receive chemical anesthetics or analgesics. We experimentally investigated whether the administration of lidocaine (a local analgesic at similar to 1 mg/kg body mass) to electroanesthetized fish resulted in any welfare-relevant differences in the behavior and physiology of Largemouth Bass Micropterus salmoides during and after standardized intracoelomic tag implantation surgeries relative to a group that received a saline sham. We also used multiple control treatments to examine potential behavioral and physiological effects of handling, electroanesthesia, surgery, and the drug administration process. We quantified voluntary movements on the surgery table, ventilation rates after surgery, reflexes, and emergence/exploration in a behavioral arena. Primary and secondary stress biomarkers also were used to evaluate physiological stress over a 2-h period postsurgery. The administration of lidocaine at the tested dose did not facilitate fish handling during surgery and did not affect changes in the physiological stress response relative to the saline control. Swimming activity postsurgery was lower in fish treated with lidocaine; however, other differences in behavior were negligible. Electroanesthesia alone was able to sufficiently facilitate the surgical procedures by limiting voluntary escape attempts without significantly exacerbating physiological stress from handling. There does not appear to be any advantage to adding lidocaine to the protocol.