Evaluation of a Portable Electrosedation System for Anesthetizing Mature Channel Catfish

Abstract

AbstractHybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) fry are produced by hormone‐induced spawning of Channel Catfish in hatcheries. Anesthetics are used routinely to reduce handling stress by limiting the activation of the hypothalamic–pituitary–interrenal axis hormones. As a comparison, the present study determined the efficacy of electrosedation using a portable electrosedation system (PES) and its feasibility for possible application in hybrid catfish hatcheries. The PES was evaluated at 100 V and a 25% duty cycle at 30, 60, 90, or 100 Hz to anesthetize mature Channel Catfish to stage IV of sedation. The PES was compared to the chemical sedatives tricaine methanesulfonate (MS‐222; 200 mg/L) and metomidate hydrochloride (Aquacalm; 6 mg/L). The PES at 30 Hz anesthetized Channel Catfish in 4 s, significantly faster than the 120 s needed for MS‐222. However, the mean (±SE) time to recover from anesthesia and mean plasma cortisol response were similar (P > 0.05) with MS‐222 (104 ± 9 s; 35 ng/mL) and the PES (119 ± 15 s; 32 ng/mL). Relative fecundity of fish sedated by the PES and MS‐222 averaged 5,222 and 5,593 eggs/kg of body weight (BW), respectively; percent hatch averaged 46.9% and 50.4%, respectively; and hybrid catfish fry production averaged 1,644 and 1,711 fry/kg BW, respectively. Relative fecundity, percent hatch, and hybrid fry production were not significantly different between the PES and MS‐222 groups (P > 0.05). No internal injuries were noted in any of the fish subjected to electrosedation. The PES at 30 Hz effectively anesthetized female Channel Catfish with a quicker induction time, provided moderate time to recover from anesthesia, and elicited a cortisol response, with no known internal injuries. The results suggest that the PES has the potential to replace MS‐222 usage in hybrid catfish hatcheries. The PES is environmentally safe, does not expire or degrade, and requires no disposal or withdrawal period.