Efffects of handling methods on cortisol response and reproductive performance to produce hybrid catfish fry

Authors: Peterson, Brian; Chatakondi, Nagaraj

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2019
Publication Date: 3/1/2020
Citation: Peterson, B.C., Chatakondi, N.G. 2020. Efffects of handling methods on cortisol response and reproductive performance to produce hybrid catfish fry. North American Journal of Aquaculture. 82:153-158.

Interpretive Summary: There is a need to optimize production protocols to improve the efficiency of hybrid (female Channel Catfish Ictalurus punctatus x male Blue Catfish I. furcatus) embryo production in commercial catfish hatcheries. The present study compared two methods of handling Channel Catfish broodfish from pond to hatchery. Sexually mature females were seined and transported in a hauling truck to the hatchery prior to being hormone injected. Fish placed in soft-mesh bags (confined) were compared to fish allowed to freely swim (non-confined) in the hauling truck and raceway in the hatchery. The fish were bled at seining (0 h), after transport to the hatchery (1 h), and while in the raceway at 4 and 24 h, respectively and plasma levels of cortisol were measured. All fish were placed in a soft-mesh bag to monitor ovulation and fish were stripped spawned and relative fecundity (eggs/kg of body weight) and the number of fry/kg body weight of body weight were determined. Results showed that cortisol levels were high after seining in both groups. Cortisol concentrations were lower at 1 and 4 h in the non-confined group compared to the confined group. By 24 h, cortisol levels decreased in both treatment groups. Average relative fecundity (9,617 vs 8,576) and the number of fry/kg body weight (3,039 vs 2,710) were higher in the non-confined compared to the confined fish. Minimizing handling stress during transport and holding gravid fish (non-confined) for four hours in hatchery tanks prior to hormone injection appears to be beneficial for hatchery production of hybrid catfish fry.

Technical Abstract: There is a need to optimize production protocols to improve the efficiency of hybrid (female Channel Catfish Ictalurus punctatus x male Blue Catfish I. furcatus) embryo production in commercial catfish hatcheries. The present study compared two methods of handling Channel Catfish broodfish from pond to hatchery. Sexually mature females (average weight = 3.9 kg/fish) were seined and transported in a hauling truck to the hatchery prior to being hormone injected. Fish placed in soft-mesh bags (confined) were compared to fish allowed to freely swim (non-confined) in the hauling truck and raceway in the hatchery. The fish were bled at seining (0 h), after transport to the hatchery (1 h), and while in the raceway at 4 and 24 h, respectively and plasma levels of cortisol were measured. All fish were placed in a soft-mesh bag to monitor ovulation and fish were stripped spawned and relative fecundity (eggs/kg of body weight) and the number of fry/kg body weight of body weight were determined. Results showed that cortisol levels were high after seining in both groups. Cortisol concentrations were lower at 1 and 4 h in the non-confined group compared to the confined group (P < 0.05). By 24 h, cortisol levels decreased in both treatment groups. Average relative fecundity (9,617 vs 8,576) and the number of fry/kg body weight (3,039 vs 2,710) were higher in the non-confined compared to the confined fish (P = 0.05). Minimizing handling stress during transport and holding gravid fish (non-confined) for four hours in hatchery tanks prior to hormone injection appears to be beneficial for hatchery production of hybrid catfish fry.