Evaluation of portable electrosedation system (PES) for anaesthetizing channel catfish to produce channel x blue hybrid catfish embryos in hatcheries

Authors: Chatakondi, Nagaraj; KELLY, ANITA - University Of Arkansas At Pine Bluff

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2019
Publication Date: 7/19/2019
Citation: Chatakondi, N.G., Kelly, A.M. 2019. Evaluation of portable electrosedation system (PES) for anaesthetizing channel catfish to produce channel x blue hybrid catfish embryos in hatcheries. North American Journal of Aquaculture. 81:269-274.

Interpretive Summary: Channel x blue hybrid catfish are increasingly raised in commercial catfish ponds in Southeastern USA because of superior production traits. Handling stress on channel catfish is unavoidable and hence the only FDA approved chemical sedative, Tricaine Methanesulphonate (MS222) is used to reduce physical damage and handling stress for routine procedures. Under practical conditions, broodfish are often exposed to higher concentration and held for longer duration in sedative solution than required to result in an increased stress response that would succumb to disease and or post-spawning mortality. The present study was conducted to determine the efficacy of a physical sedative, portable electrosedation (PES) to sedate channel catfish and to determine feasibility of PES for possible application in hybrid catfish hatcheries. The results of the study are important to commercial hybrid catfish hatcheries. The study suggests PES has a shorter sedation time and moderate time to recover from sedation. Stress response and reproductive performance of PES sedated fish were comparable to MS222 sedation. With the advantages of controlled sedation exposure (dose and duration), no discharge or accumulation of sedative during routine sedation, and minimal recurring costs to sedate fish with PES in hatcheries would improve the efficiency of hatchery production. Even though PES has a one-time significant cost but has a potential to replace the only FDA approved chemical sedative, MS222 used by food fish farmers.

Technical Abstract: Female Channel Catfish Ictalurus punctatus x male Blue Catfish I. furcatus hybrid fry are produced by hormone-induced spawning of Channel Catfish in hatcheries. Anesthetics are used to make the fish easier to handle and reduce the stress in Channel Catfish by reducing the activation of the hypothalamus-pituitary-interrenal (HPI) axis hormones associated with handling stressors. The present study was conducted to determine 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 volts, 25% duty cycle at 30, 60, 90 or 100 Hz to sedate mature Channel Catfish to stage IV of sedation. Electrosedation was compared with 200 mg/L of tricaine methanesulfonate (MS-222) and 6 mg/L of metomidate hydrochloride (Aquacalm). Electrosedation at 30 Hz sedated Channel Catfish in 4 seconds, significantly faster than the 120 seconds needed for MS-222 sedation. However, time to recover from sedation and mean plasma cortisol response with MS-222 (104 + 9 sec; 35 ng/mL) and PES (119 + 15 sec; 32 ng/mL) were similar (P > 0.05). Relative fecundity of fish sedated by electrosedation and MS-222 averaged 5222 eggs/kg BW; 5593 eggs/kg BW, percent hatch 46.1%; 50.9%, and hybrid catfish fry production 1644 fry/kg BW; 1711 fry/kg BW, respectively, were all similar (P > 0.05). No internal injuries were noted in any of the fish subjected to electrosedation. Electrosedation effectively sedated female Channel Catfish with a quicker induction time, provided moderate time to recover from sedation, and elicited a stress response with no known internal injuries. The results of the study suggest PES has a potential to replace the existing FDA approved chemical sedative to improve the efficiency of hybrid catfish fry production in hatcheries. Electrosedation is also environmentally safe as it does not expire nor degrade and requires no disposal or withdrawal period.