Submitted to: Southeastern Association of Fish and Wildlife Agencies Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2014
Publication Date: 10/19/2014
Citation: Chatakondi, N.G., Peterson, B.C. 2014. Plasma cortisol stress response in channel catfish, Ictalurus punctatus influences susceptibility to Edwardeseilla ictaluri. Southeastern Association of Fish and Wildlife Agencies Conference. 38:23.
Technical Abstract: Cortisol is a primary stress hormone in fish as its plasma variations correlate with the occurrence of various stressful situations. Past studies have demonstrated that fish subjected to handling stress or poor water quality had a reduced ability to resist pathogens. Channel catfish fingerlings that belonged to a select strain, developed at our facility were subject to standardized hypoxia stress test. We classified the fish either as ’low responders (LR)’ or ‘high responders (HR)’ based on their cortisol stress response, and were pit-tagged for identification. HR and LR fish were held either in separate or co-cultured in replicated aquaria, supplied with flow-through water and diffused air. We evaluated the susceptibility of LR and HR channel catfish fingerlings to Edwardseilla ictaluri disease challenge under controlled conditions. At the end of 21 days post-challenge, mean percent of mortalities of LR were 15 percent lower (P<0.05) than mean HR group. The difference in mortalities were more pronounced, when the two groups of fish were co-cultured. However, the mean days to death between the groups was similar, suggesting the mode of the action of the pathogen is similar in channel catfish with varying cortisol stress response. Quantitative genetic studies in channel catfish have revealed a moderate to high degree of heritability of the cortisol stress response trait, and the validity of this trait for genetic improvement is presently being evaluated. Stress is unavoidable in aquaculture or stock enhancement programs in natural waters, hence LR fish would be resilient and adaptable for handling and associated stressful conditions.