Location: Warmwater Aquaculture Research UnitTitle: Impacts of Bolbophorus damnificus (Digenea: Bolbophoridae) on production characteristics of channel catfish, Ictalurus punctatus, raised in experimental ponds Author
Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2013
Publication Date: 8/2/2013
Citation: Wise, D.J., Li, M.H., Griffin, M.J., Robinson, E.H., Khoo, L.H., Greenway, T.E., Byars, T.S., Walker, J.R., Mischke, C.C. 2013. Impacts of Bolbophorus damnificus (Digenea: Bolbophoridae) on production characteristics of channel catfish, Ictalurus punctatus, raised in experimental ponds. Journal of the World Aquaculture Society. 44(4):557-564. Interpretive Summary: Laboratory and field studies were conducted to evaluate sublethal acute and chronic infections of B. damnificus on catfish production. This work confirmed previous studies showing that mild infections reduced feed consumption, fish production and economic returns. However, it also demonstrated that once the metacercarial cysts are fully developed and the source of infection is removed, there is little impact on performance of the fish.
Technical Abstract: Bolbophorus damnificus was recognized as a threat to channel catfish, Ictalurus punctatus, production in Louisiana and Mississippi in 1997 and 1999, respectively. Severe to moderate outbreaks (=34% prevalence) are correlated to heavy losses, but impact of mild outbreaks with low prevalence (<33%) was unknown. Laboratory and field studies were conducted to evaluate sublethal acute (early stage) and chronic (late stage) trematode infection impacts on catfish production. Fish raised in ponds seeded with ram's horn snails from ponds harboring active B. damnificus outbreaks resulted in infection prevalence ranging from 1.6 to 20.4%. Compared to fish raised in ponds not seeded with infected snails (0% prevalence), fish biomass, number harvested, and total feed fed were significantly lower. These data agree with previous studies where mild infections reduced feed consumption, fish production, and economic returns. Infected fish were collected from ponds and used in a laboratory growth study. Once removed from the infection source, weight gain, growth rate, feed consumption, and feed efficiency were equal to or greater than trematode-free fish. This suggests that although early B. damnificus infection (premetacercarial development) can severely impact production, infection has little impact on performance once metacercarial cysts are fully developed, and the infection source is removed.