Location: Warmwater Aquaculture Research UnitTitle: Developing a low cortisol responsive line of channel catfish, Ictalurus punctatus Author
Submitted to: International Symposium on Fish Endocrinology
Publication Type: Abstract Only
Publication Acceptance Date: 5/27/2016
Publication Date: 6/28/2016
Citation: Chatakondi, N.G., Peterson, B.C. 2016. Developing a low cortisol responsive line of channel catfish, Ictalurus punctatus. International Symposium on Fish Endocrinology. P. 93.
Technical Abstract: Nagaraj G. Chatakondi and Brian C. Peterson USDA ARS Warmwater Aquaculture Research Unit, 141 Experiment Station Road, Stoneville, MS 38776. email@example.com Channel catfish, Ictalurus punctatus is the most important farm-raised aquacultured species in the USA. Stressors in aquaculture are unavoidable and stressors exacerbate disease susceptibility of cultured fish. Developing mitigating strategies to overcome stress in aquaculture conditions is a strategy to develop low cortisol responding fish to standardized stressors. The goals of the study were to determine cortisol responsiveness was a heritable trait in channel catfish and to determine if a relationship exist between cortisol responsiveness and performance traits. Low responding (LR) and High responding (HR) parental fish were identified by periodic stress tests. Four pairs of LR and four pairs of HR parental fish were strip-spawned to produce 64 families with four categories of progeny: LRxLR, LRxHR, HRxLR and HRxHR. All the families were produced within a 3-hour interval and hatched in individual aquarium under optimal conditions. After documenting percent fertilization, neurulation and hatch, the density of fish were reduced to 200 fish per aquarium. At the end of six weeks, the fish density was further reduced to 10 fish per aquarium. Excess fish were stocked equally in two 0.25 acre ponds. At 4 months post-hatch, catfish fingerlings raised in individual aquaria were subjected to standardized stress condition to measure plasma cortisol concentration (CORT) and body weight (BW) of individual fish. Traits, BW and CORT were analyzed by a linear animal model in a bivariate setup using ASREML. Heritability estimates were low for body weight (h2=0.12 +0.06), and moderate for cortisol (h2=0.42+0.09), and the genetic correlation (rg) between body weight and cortisol was negative (rg=-0.64+0.24). The cortisol responsive trait was heritable in channel catfish and negatively correlated with body weight. At 6 months post-hatch, 1600 fish raised in ponds were fin-clipped, pit-tagged, weighed (g), measured (mm), and were stocked equally in three 0.1 acre ponds. Progeny are presently genotyped with DNA microsatellite markers to identify parental fish. Cortisol responsiveness of the families will be compared with performance traits of pond-raised channel catfish.