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Fish Health Management. GOALS : Production of healthy, high quality fish. Principles of Health Maintenance. Maintain conditions which are designed to optimize growth, feed conversion, reproduction and survival Intensive aquaculture – Enhance natural resistance. Maintaining Health.
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Fish Health Management • GOALS : • Production of healthy, high quality fish
Principles of Health Maintenance • Maintain conditions which are designed to optimize growth, feed conversion, reproduction and survival • Intensive aquaculture – • Enhance natural resistance
Maintaining Health • Inverse relationship between environmental quality and disease status of fish • Changes occur over time (type of system) • Emphasis of Health management: • Physical features of facility • Use of genetically improved fish • “SPF” stocks • Environmental control • Prophylactic/preventative therapy • Feed quality and quantity
Stress • Adverse situation that affects the well-being of individual animals
Stress related disease • Environmental associated • Microbial diseases • Decreased resistance to pathogens • Endemic pathogens
Location of site • Soil, water and fish species must be compatible • Chose site properly • Pond aquaculture • Soil characteristics • Drainage
Avoiding exposure • Best method to control infectious disease • Water is effective at delivering pathogens to fish (endemic)
Avoiding exposure (cont.) • U.S.: Title 50 • Other countries? • Quarantine • Isolate stocks for a predetermined period before contact with resident fish • Eradication of Stocks • Last resort! • Is it worth it? • Can you manage around it without introducing disease to area
Avoiding exposure (cont.) • Example: • VHSV (1989) Washington • Destroyed adults that were found to have virus • Destroyed juveniles • Great lakes (lake trout) Epidermal epitheliotropic disease (herpesvirus) • Destroyed fish and disinfected contaminated facilities • Appears to have worked • BKD (Wyoming) (1990) • Destruction of RBT, lake, CTT, and BrT brood stock • Based on highly sensitive detection technique (ELISA) • No evidence for disease • “Was the cost and consequence greater than the value of what was saved?”
Exposing Dose • Once pathogen load increases (due to poor resistance) = DISEASE
Extent of contact • Infection vs Disease? • Facultative – • Obligate – require host to complete life cycle • Viruses, some bacteria, and few parasites • Route of transmission • Carriers
Protection through segregation • Young fish/newly hatched fish • Fingerlings • Immunity increasing • Growout • Approaching market/release size • Very resistant to disease • Can survive in poorest water quality
Addition of new fish • Should take needed precautions when adding new fish to existing stocks • Home aquaria or large facilities
Breeding and Culling • Important in the development of domesticated stocks that perform well • Improve by selecting for desired traits • Future possibilities (genetic engineering) • Gene manipulation • Hybridization/transgenic
Eradication/prevention/control • Eradication: • Prevention: • Control: Reduction of problem to an economically/biologically manageable level
Anticipating problems • Good health records for each pond • Water quality/quantity • Stay on top of things!!
Fish Health Monitoring • Early diagnosis • Know what “normal” is!
Question? You are in charge of fish health monitoring at an aquaculture facility. During morning rounds you notice that a first use pond containing RBT (50g/fish) is having some problems. Fish appear lethargic, and some dark fish are observed. • What possible problems may be causing this? • How would you narrow the possibilities down? • You suspect the problem to be disease related, what would you do?