Author
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Mitchell, Andrew |
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Submitted to: Annual Eastern Fish Health Workshop
Publication Type: Abstract Only Publication Acceptance Date: 2/8/2004 Publication Date: 3/22/2004 Citation: Mitchell, A.J. 2004. Bolbophorus infections in catfish: identification, impact and treatment [abstract]. Annual Eastern Fish Health Workshop. p. 58. Interpretive Summary: Technical Abstract: Bolbophorus trematodes infect pelicans (the definitive host), rams-horn snails (first intermediate host), and a number of fish species (second intermediate host). These trematodes are characterized by having lateral pseudosuckers surrounding the oral sucker, interconnecting excretory channels, hind- and forebody, a holdfast organ, and a clear parasite cyst within the host cyst. The taxonomy of these parasites is in transition and at present there are at least four known Bolbophorus species with two (B. damnificus and B. sp) identified in the US. Prior to 2002, B. confusus was the name given to most of these trematodes worldwide, but it is now considered the name of one species found in Europe. Bolbophorus damnificus has been found in the flesh of channel catfish and in one case a fathead minnow, while B. sp. has been found in several fish including some from the cyprinid, centrarchid, and percichthyid families. Bolbophorus damnificus has been responsible for serious losses in the catfish industry and is now found on more than 50 catfish farms in Arkansas, California, Louisiana, and Mississippi. At present, the trematode is spreading to new farms and fish losses continue to be reported throughout the industry. Pond shoreline treatments of copper sulfate and hydrated lime as well as the stocking of black carp seem to have lessened the impact of the parasite. Ten pounds of copper sulfate applied along 250 ft of shoreline in a 6 ft wide band reduced the rams-horn snails that host B. damnificus to an average of about 5% in the study ponds at temperatures above 21°C. The hydrated lime treatment, although reported as effective, is not well defined or tested: recommended treatment rate per shoreline length and treatment width varied, the influence of temperature on the treatment was unknown, and no treatment results were published. In tests initiated to define the effectiveness of the hydrated lime treatment and to compare it to the copper sulfate treatment, it was found a rate of about 90 lbs of hydrated lime applied along 100 ft of shoreline in a 3 ft wide band should make an effective treatment. More testing is planned. |
