Co-culture of channel catfish with hybrid catfish facilitates 'herd effect' to improve production performance

Authors: Chatakondi, Nagaraj; Peterson, Brian

Submitted to: American Fisheries Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/9/2014
Publication Date: 3/18/2014
Citation: Chatakondi, N.G., Peterson, B.C. 2014. Co-culture of channel catfish with hybrid catfish facilitates 'herd effect' to improve production performance. American Fisheries Society Annual Meeting. P.22.

Interpretive Summary:

Technical Abstract: Herd effect is an epidemiological phenomenon, where the presence or proximity of a certain proportion of improved (superior) individuals improve the performance of less improved (normal) individuals. Channel catfish, Ictalurus puntatus is the single largest aquaculture species cultured in US. However, catfish production has been declining due to inefficiencies in farming practices and influx of cheap imports. Channel catfish ' x blue catfish, I.furcatus ' F1 hybrid represent a major improvement in the production efficiency due to its higher growth rate, better survival, and improved production compared to channel catfish under research and commercial conditions. However, hybrid catfish fry production in hatcheries is expensive and a time regimented process. Presently, hybrid catfish fingerling production cannot meet the demand of commercial food fish producers in the catfish industry even at higher prices. One approach to augment lower hybrid catfish fingerlings availability would be to co-culture hybrid catfish with channel catfish in production units to implicate herd effect for higher aquaculture production. We hypothesize channel catfish (lower performing fish) in the presence of hybrid catfish (better performing fish) at optimal proportions improve the performance traits of channel catfish. To test our hypothesis, we co-cultured channel catfish and hybrid catfish in five proportions (0, 25, 50, 75 and 100%) in six replicated 80 L flow-through aquaria per proportion under controlled conditions for a 8 week growth study. The second growth study with similar proportions of genotypes was conducted in six replicated 600 L tanks supplied with recirculated pond water for a 16 week growth study. Production traits (growth, feed conversion, and survival) did not differ between the two genotypes at the five proportions. At the end of the growth study, fish raised in controlled aquaria were subject to disease challenge with Edwardsiella ictaluri, the bacterium that causes ESC disease. In this third study, percent mortality of channel catfish when co-habituated with an equal proportion of hybrid catfish was significantly (P <0.05) lower compared to channel catfish co-cultured with the other four proportions of hybrid catfish. The time of the death was also delayed in channel catfish in this treatment. This improved disease protection in channel catfish may be to the attributed to the ‘herd effect’ phenomenon. This preliminary data suggests that co-culture of channel catfish and hybrid catfish in equal proportions may reduce the cost of raising US farm raised catfish in the catfish industry.