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U.S. Department of Health and Human Services

Animal & Veterinary

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AQUACULTURE UPDATE

FDA Veterinarian Newsletter September/October 1999 Volume XIV, No V

Aquaculture is becoming an increasingly important source of fish available for human consumption. As the number of aquaculture facilities grows, so does the need to develop safe and effective drugs for treating fish diseases. It is also important to understand the effect these treatments have on non-target organisms and on the aquatic environment. As a result, the FDA's Center for Veterinary Medicine (CVM) Office of Research (OR) has greatly expanded its commitment to aquaculture research. In January 1999, Renate Reimschuessel V.M.D., Ph.D., accepted a position at CVM to begin to develop a research program in aquaculture.

Dr. Reimschuessel, former Director of the Aquatic Pathobiology Center at the University of Maryland School of Medicine, has over fifteen years experience conducting research on aquatic animals. She has a multidisciplinary background and has published work in the areas of fish husbandry, aquatic toxicology, microbiology, pharmacokinetics, developmental biology and pathology.

One of Dr. Reimschuessel’s first tasks is to enhance the capacity of the current aquaculture facility. Additional water delivery lines are being installed to increase water flow to the fish systems and improve water quality. Work is also in progress to construct closed, recirculating water systems to simulate more intensive aquacultural techniques.

"This is an incredible facility that will allow us to conduct state-of-the-art aquaculture research" stated Dr. Reimschuessel as she toured the building. There are four main research rooms of approximately 4600 sq. ft., one radioisotope fish lab of 600 sq. ft., a storage room, two mechanical/filtration rooms and two support rooms which house computers, desks and a small library. Incoming water from either the well or municipal supply goes into the primary filtration system comprised of separate calcite and carbon contactors. Temperature is controlled by separate heat exchangers and chillers, which provide hot and cold running water to mixing valves at the fish tanks. A centralized computer system monitors the flow-through water system temperature and pH.

Outside the building is a 25,000-gallon water storage tank with venturi systems to remove carbon dioxide from the well water. Wastewater is sent to either two 20,000-gallon "clean" water holding tanks or two 10,000-gallon radioactive wastewater holding tanks. Dr. Reimschuessel is in the process of obtaining three 1500-gallon tanks to hold saltwater.

Research at the facility will focus on both regulatory priorities and the needs of the aquaculture community. Species that will be studied during the first year include tilapia (Oreochromis sp.), rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar), channel catfish (Ictalurus punctatus) large mouth bass (Micropterus salmoides), toadfish (Opsanus tau), and goldfish (Carassius auratus). All of these species, except goldfish, are currently raised or maintained for food purposes. Goldfish will serve as a model for ornamental fish and as a disease model. Goldfish are an established model of infection by atypical Mycobacteria spp.(fish pathogens as well as increasingly important pathogens for immune-compromised humans).

Dr. Reimschuessel has designed her research objectives, in general, to provide data to assist the Food and Drug Administration in assuring that fish derived from the aquaculture production environment are safe for human consumption. Her priorities include studying the biodistribution, residue persistence, metabolism, efficacy, and environmental effects of drugs and other chemicals used in aquaculture. There will be a large effort to develop a rationale for crop grouping (grouping species for drug approvals based on similarities in anatomy, physiology and drug metabolism). Other studies are designed to investigate the impact of drugs on the environment, non-target species and the pathogens associated with aquatic species. Of increasing importance are studies designed to understand the development and transmission of antimicrobial resistance in both pathogens and environmental microbes. Understanding those mechanisms will help in the development of treatment strategies that minimize the development of resistant pathogens.

Dr. Reimschuessel is currently preparing research protocols designed to address a number of these priorities. She is actively collaborating with scientists conducting aquaculture-related research at the University of Maryland, Johns Hopkins University, Fort Detrick, and the Maryland Department of Natural Resources. She also teaches veterinary students and veterinarians in the AquaVetâ program each May at the Marine Biological Laboratory, Woods Hole, Massachusetts. She will be developing a research internship program at CVM for fourth-year veterinary students interested in aquaculture. She says "I hope to continue getting veterinarians involved in fish medicine and research. It is a specialty in its infancy. Programs that educate veterinarians about aquatic species will help increase correct diagnosis and treatment of diseases, thereby reducing arbitrary or inappropriate use of therapeutic agents in farm-raised fish. With CVM’s increasing research efforts and support for the minor species drug program, we should be able to provide veterinarians with a greater choice of safe and effective treatments."