Transcript SELF DEFENSE SYSTEMS

Fish Health Management
• GOALS :
– Production of healthy, high quality fish
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Principles of Health Maintenance
• Maintain conditions which are designed
to optimize growth, feed conversion,
reproduction and survival
• Intensive aquaculture –
• Enhance natural resistance
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Maintaining Health
• Inverse relationship between environmental
quality and disease status of fish
• Changes occur over time (type of system)
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• Emphasis of Health management:
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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 wellbeing of individual animals
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Stress related disease
• Environmental associated
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• 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)
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Avoiding exposure (cont.)
• U.S.: Title 50
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– 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)
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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
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• 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
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– Carriers
Protection through segregation
• Young fish/newly hatched fish
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• Fingerlings
– Immunity increasing
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• Growout
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• 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
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Breeding and Culling
• Important in the development of
domesticated stocks that perform well
• Improve by selecting for desired traits
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• Future possibilities (genetic engineering)
– Gene manipulation
– Hybridization/transgenic
Eradication/prevention/control
• Eradication:
• Prevention:
• Control: Reduction of problem to an
economically/biologically manageable level
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Anticipating problems
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• Good health records for each pond
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• Water quality/quantity
• Stay on top of things!!
Fish Health Monitoring
• Early diagnosis
– Know what “normal” is!
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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.
1. What possible problems may be causing this?
2. How would you narrow the possibilities
down?
3. You suspect the problem to be disease related,
what would you do?