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Fish Health Management

Fish Health Management. Dr. Craig Kasper Aquaculture Disease Processes FAS 2253. Fish Health Management. GOALS : Prevent introduction of disease to healthy animals. Prevent propigation of existing disease agents. Production of healthy, high quality fish.

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Fish Health Management

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  1. Fish Health Management Dr. Craig Kasper Aquaculture Disease Processes FAS 2253

  2. Fish Health Management • GOALS : • Prevent introduction of disease to healthy animals. • Prevent propigation of existing disease agents. • Production of healthy, high quality fish.

  3. Principles of Health Maintenance • Maintain conditions which are designed to optimize growth, feed conversion, reproduction and survival. • Intensive aquaculture – high numbers, close quarters, lots of food!! (optimal?) • Enhance natural resistance • Well managed fish have healthy immune systems! • Healthy fish give rise to healthier offspring!

  4. Maintaining Health • Inverse relationship between environmental quality and disease status of fish • Changes occur over time (type of system) • Water quality degrades. • Fish become more crowded. • Emphasis of Health management: • Physical features of facility • Use of genetically improved fish • “SPF” stocks • Environmental control • Prophylactic/preventative therapy • Feed quality and quantity

  5. REM: Stress • Adverse situation that affects the well-being of individual animals...

  6. Stress related disease • Environmental associated • Wild fish are in equilibrium with there pathogens. • Captive fish are much more effected by changes in temp. or water quality due to excessive crowding, handling, etc. • Microbial diseases • Decreased resistance to pathogens • Endemic pathogens

  7. Location of site • Soil, water and fish species must be compatible • Chose site properly • Pond aquaculture • Soil characteristics • Drainage Good, bad, or just ugly??

  8. Avoiding exposure • Best method to control infectious disease • Water is effective at delivering pathogens to fish (endemic) • Don’t feed contaminated feed.

  9. Avoiding exposure • REM: U.S.: Title 50? • What about other countries? • Do they have regulations? • Quarantine • Isolate fish 2 weeks + • Eradication of Stocks • Last resort! • Is it worth it? • Can you manage around problem?

  10. Avoiding exposure (cont.) • Example: • VHSV (or Egtved) Washington (1989) • Destroyed adults that were found to have viru • 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?”

  11. Exposing Dose • To be sick, fish must be exposed! If no exposure, liklihood of disease greatly reduced. • Introduction of disease agent = potential trouble as we disscussed last time. • Once pathogen load increases (due to poor resistance) = DISEASE • Exposing dosage data usually confined to toxicity studies.

  12. Extent of contact • Infection vs Disease? • Facultative – may live under many conditions • Obligate – require host to complete life cycle • Viruses, some bacteria, and few parasites • Route of transmission • Oral • External • Vertical • Horizontal • Direct exposure • Carriers

  13. Protection through segregation • Young fish/newly hatched fish • Only innate immunity • Highly suceptable to stress and water quality issues • May need medicated feed. • Fingerlings • Immunity increasing • survive poor water quality for short duration. • Growout • Immune system well established. • Approaching market/release size • Very resistant to disease • Can survive in poorest water quality

  14. Addition of new fish • Should take needed precautions when adding new fish to existing stocks...duh!! • Home aquaria or large facilities • Again...Quarantine!

  15. Breeding and Culling • Important in the development of domesticated stocks that perform well • Improve by selecting for desired traits • disease resistance • fast growth • tolerance of stressors • Future possibilities (genetic engineering) • Gene manipulation • Hybridization/transgenic

  16. REM: EPC • Eradication: Kill ‘em all!! • Prevention: Kill what kill’s ‘em!! • Control: Reduction of problem to an economically/biologically manageable level • Do all you can. • Be prepared for the worst. • Sometimes fish just get sick!!

  17. Anticipating problems • Plan ahead. • Good health records for each pond. • Good observations. • Good feed. • Water quality/quantity. • Stay on top of things!!

  18. Fish Health Monitoring • Early diagnosis • Know what “normal” is! • Know what treatments are available. (and how to utilize them.) • Know what abnormal is. • Remain proactive.

  19. 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?

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