Evaluation of a Portable Electrosedation System for Anesthetizing Mature Channel Catfish

Abstract

Hybrid 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.

Best practices for non‐lethal blood sampling of fish via the caudal vasculature

“…Any lingering effects of the sedation agent may contribute to alterations in natural behaviour (Losey & Hugie, 1994;Mettam et al, 2011;Prystay et al, 2017) or lead to postrelease predation (reviewed in Raby et al, 2014). Lingering effects would be suboptimal for studies in which post-release behaviour is monitored (i.e., telemetry studies; see Brownscombe et al, 2019) g., Chatakondi & Kelly, 2019;Nguyen et al, 2018;Rucinque et al, 2018;Trushenski et al, 2017). Nonetheless, it is possible, and often preferable, to sample fish from the caudal vasculature without the use of any anaesthesia (as described later).…”

“…Low‐voltage electricity has been proposed as an anaesthetic to aid in fish restraint because of relatively short recovery times after exposure ( i.e ., seconds; Vandergoot et al ., 2011; Trushenski & Bowker, 2012; Ward et al ., 2017; Abrams et al ., 2018; Reid et al ., 2019). Indeed, because of its relatively low and transient impacts, electricity is widely used as an anaesthetic in aquaculture ( e.g ., Chatakondi & Kelly, 2019; Nguyen et al ., 2018; Rucinque et al ., 2018; Trushenski et al ., 2017). Nonetheless, it is possible, and often preferable, to sample fish from the caudal vasculature without the use of any anaesthesia (as described later).…”

“…g., Chatakondi & Kelly, 2019;Nguyen et al, 2018;Rucinque et al, 2018;Trushenski et al, 2017). Nonetheless, it is possible, and often preferable, to sample fish from the caudal vasculature without the use of any anaesthesia (as described later).…”

Effects of Handling Methods of Gravid Channel Catfish on Cortisol Response and Reproductive Performance to Produce Hybrid Catfish Fry

“…However, there are several inefficiencies in the production of hybrid fry. The production of hybrid catfish requires crossing two separate catfish species, which requires seining, selecting, and transporting broodfish to the hatchery and then injecting the broodfish with hormones, checking for ovulation, and finally stripping eggs from the ovulating females, all of which can be stressful to the fish (Chatakondi and Kelly 2019). Strip-spawned eggs are often of a lower quality than natural pondspawned eggs because of handling stress, hormone treatment, variations in the sexual maturation of fish, and possible mechanical damage to the eggs that is caused by stripping (Chatakondi and Torrans 2012a).…”