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United States Department of Agriculture

Agricultural Research Service

Research Project: EVALUATION OF COMPOUNDS AND STRATEGIES FOR CONTROLLING AQUATIC ANIMAL DISEASE
2007 Annual Report


1a.Objectives (from AD-416)
Develop data needed to demonstrate safety (animal, human, and environmental) and efficacy of compounds that are relevant to the needs of aquaculture. Determine the efficacy of compounds, biological control strategies, clearance rate and pathogenesis of parasites and fungi applicable to catfish, baitfish, and Morone sp. culture.

Improve performance efficiency of important warm water aquaculture species by identifying optimal management practices related to mitigation of disease outbreaks, evaluation of blue/channel hybrid catfish production characteristics and disease resistance, evaluation of oxygen transfer technology related to cost, and harvesting and transport.


1b.Approach (from AD-416)
Submit the FDA-required Efficacy data for control of Ichthyophthiriasis by Potassium Permanganate. Submit the environmental assessment data for potassium permanganate and copper sulfate on channel catfish in earthen ponds. Submit the target animal safety data for potassium permanganate in channel catfish. Use in vivo challenge models and in vitro assays to investigate the efficacy of florofenicol against streptococcus infection in hybrid striped bass and tilapia. Evaluate the safety of florofenicol use in hybrid striped bass and tilapia. Evaluate praziquantel for control of asisan tapeworm in grass carp and golden shiners. Evaluate the biological control of trematode vectoring mollusks by determining comparative consumption and preference by snail-eating fishes. Determine the clearance rate of the catfish trematode (bobophorus) in channel catfish and the gil trematode in hybrid striped bass, golden shiners, and channel catfish. Determine the prevalence of trematodes in black and yellow crown night herons, little blue herons, snowy egrets, cattle egrets, and belted kingfishers. Determine efficacy of dimilin for the control of anchor parasites and fish lice in morone sp., golden shiners, and gold fish. Evaluate copper sulfate treatments to control snails under commercial farm conditions. Use the DNA sequence of F. columnare and F. psychrophilum or F. Branchiophilum to detect and "fingerprint" strains of pathogens by molecular techniques as restriction fragment length polymorphism (RELP) using polymerase chain reaction, or pulse field gel electrophoresis (PEGE).


4.Accomplishments
DOSE CONFIRMATION STUDIES FOR USING COPPER SULFATE TO CONTROL FUNGUS ON CATFISH EGGS; STEPS TOWARD FDA-APPROVAL: This research addresses egg mortality from fungus (i.e., watermolds) aggressively destroying eggs in catfish hatcheries. A laboratory dose-confirmation study by scientists at the HKD Stuttgart National Aquaculture Research Center was completed to demonstrate a statistical difference between treating catfish eggs daily with 10 ppm copper sulfate and a sham treatment; this research is required by FDA for a future label claim. The impact will be to improve the economics of the industry by providing increased survival rates in catfish hatcheries. (NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

IMPROVED TREATMENT FOR ASIAN TAPEWORM IN BAIT FISH: Commercially raised fish infected with Asian tapeworms have limited potential for sale and therefore can be a detriment to the producer. The efficacy of bath treatments of praziquantel against these tapeworms was evaluated by scientists at the HKD Stuttgart National Aquaculture Research Center in heavily infected grass carp, and a 24-h bath treatment of 0.75 mg/L eliminated all tapeworms from the fish. The impact will be an economic benefit by allowing producers to ship their fish to states that require tapeworm-free fish. (FY2008 milestone of NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

USING PCR TO RAPIDLY IDENTIFY FUNGUS AFFECTING CATFISH HATCHERIES: This research addresses the incorrect diagnoses of egg diseases (bacterial growths may appear to be similar to fungal growths) in catfish hatcheries. Fungus (i.e., watermolds) isolates were cultured from catfish egg masses and identified using PCR/sequencing and morphological characterizations of sexual/asexual reproductive structures by scientists at the HKD Stuttgart National Aquaculture Research Center. Four different types of fungus were identified from 18 samples, and their sequences have been deposited in the internet database GenBank. The impact of this accomplishment is an increased scientific knowledge and quick identification of fungus affecting the catfish industry. (NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

INVESTIGATIONS ON THE USE OF POTASSIUM PERMANGANATE ON COLUMNARIS: The effectiveness of this compound to columnaris-infected fish has not been widely explored in the literature. Research by scientists at the HKD Stuttgart National Aquaculture Research Center demonstrated that exposing the causative agent (/F. columnare/) to 2 mg/L for 8 h resulted in a 75% reduction of colony forming units; additionally, the compound proved effective as a prophylactic treatment against an artificially induced columnaris outbreak in catfish. Potassium permanganate significantly accelerated the mortality of acutely infected fish, but the infection method did not simulate a natural outbreak. This research demonstrates the benefits and limitations of potassium permanganate for developing effective control methods for columnaris, one of the two most costly diseases to the catfish industry in the United States. (FY2008 milestone of NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

USE OF DIQUAT TO CONTROL COLUMNARIS IN CATFISH: There are few treatments for columnaris in catfish. Scientists at the HKD Stuttgart National Aquaculture Research Center determined that infected fish treated with Diquat had significantly higher survival than infected non-treated fish. Diquat has the potential for reducing mortality from columnaris, which is one of the two most costly diseases to the catfish industry in the United States. (FY2008 milestone of NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

USING DIQUAT AS A FUNGUS TREATMENT ON CATFISH EGGS: Fungus (i.e., watermolds) growing on catfish eggs in commercial production facilities can severely limit hatching. Scientists at the HKD Stuttgart National Aquaculture Research Center determined that dosing with 25 to 50 mg/L Diquat daily until hatching begins proved effective against fungal infection, thereby increasing survival. The impact of this accomplishment is to have another treatment that could offer an affordable and effective method for controlling fungal infestations on catfish eggs. (NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

USING ICE WATER AS A NET DISENFECTANT FOR SNAIL CONTROL: The red-rim melania, an aquatic snail that carries fish parasites, can be introduced to pristine waters on fishery and sampling equipment. A treatment developed by scientists at the HKD Stuttgart National Aquaculture Research Center that uses a mixture of water, ice, and salt was found to be effective in killing all snails held in dip nets. The impact of this research is to provide an inexpensive and environmentally friendly treatment to help stop the spread of this snail and the disease organisms it vectors. (NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)

MICRODILUTION METHOD DEVELOPED FOR COLUMNARIS: A new method to determine the minimum inhibitory concentration of a compound to bacteria would be useful. A simple, accurate and reliable microdilution method was developed by scientists at the HKD Stuttgart National Aquaculture Research Center to test the susceptibility of /Flavobacterium columnare/ to antibiotics, including florfenicol. Testing of bacterial sensitivity to antimicrobials is essential for assessing the potential therapeutic value of antibiotics. This assessment will be indispensable for controlling /F. columnare/ infections, one of the two most costly infections to the channel catfish industry in the US. (FY2008 milestone of NP106, 4b Integrated Aquatic Animal Health Management, Vaccines and Medicines)


6.Technology Transfer

Number of non-peer reviewed presentations and proceedings11
Number of newspaper articles and other presentations for non-science audiences4

Review Publications
Wise, D.J., Mischke, C.C., Greenway, T., Byars, T., Mitchell, A.J. 2006. Uniform application of copper sulfate as a potential treatment for controlling snail populationsin channel catfish ponds. North American Journal of Aquaculture. 68:364-368.

Mitchell, A.J., Hobbs, M.S. 2007. The acute toxicity of praziquantel to grass carp and golden shiners. North American Journal of Aquaculture. 69:203-206.

Darwish, A.M. 2007. The efficacy of florfenicol against stretococcus iniae infection in sunshine bass. Journal of Aquatic Animal Health. 19:1-7.

Goodwin, A.E., Straus, D.L. 2006. Solid and liquid formulations of copper sulfate: Efficacy at high and low alkalinities. North American Journal of Aquaculture. 68(4):359-363.

Last Modified: 10/23/2014
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