Economic Loss Flashcards
Controlling - Environment/Host/Pathogen
How can stress be caused in aquaculture?
Over crowding
Injury/Poor handling
Environmental Conditions beyond the physical norm
What parameters can you adjust to control the environment?
- Temperature,
- Salinity
- Dissolved Oxygen
- pH
- Ammonia
Environment Example: With bitter crab disease, what can be done to minimise infection?
- virulence of hematodinium spp declines at low salinities
- Increase temperature (evidence suggests disease is more prevalent during winter months
Environment Example: With Dermo disease, what can be done to minimise infection?
- Perkinsus marines
- disease more prevalent in summer months so low temperatures and salinities would reduce virulence
- low temp and salinity also favours plasma Lysozyme production which can counteract pathogen
Environment Example: With Aeroccoccus viridians, what can be done to minimise infection?
- lobsters infected
- store lobsters at low temperatures (can only go so low as the lobsters take longer to grow so high aquaculture costs
- HOWEVER potenially ends up in physiological niche of another parasite at low temperatures - ANOPHYROIDES HAEMOPHILIA (3degrees)
What does the term pathogenic evolution mean
applying selection pressures to the pathogenic organism
What does SPF mean?
Specific pathogen free
Who/What monitors shellfish beds
CEFAS
What does CEFAS stand for?
Center for environmental, fishery and aquaculture science
What is a cheap and practical solution to minimise infection between farms?
Restricted movements - monitored by CEFA or FRS
What term is used to describe measures which prevent disease in aquaculture
Biosecurity
What ways can you control the host?
- Reduce Stock (less stress)
- Mixed Culture
- Immunostimulents
- Genetic manipulation
- Selective Breeding
Give some examples of Immunostimulents
- beta-1,3-glycans from yeast
- Peptidoglycans
What are some limitations of using immunostimulants
- Don’t seem to work against viruses
- effects on immune system are short lived
- effects are not always reproducible in situ
- effects not always confirmed by scientists
- reduced growth rate
What does SPR stand for?
Specific Pathogen Resistant
Give an example of and SPR organism
SPR shrimp = ‘Super Shrimp’
- Have been selectively bred
- Shrimp are immune to IHHNV (Infectious hypodermic and haematopoietic necrosis virus)
What are the limitations of Selective Breeding
- Aquiring survived individuals (often discarded with the rest of infected stock)
- Inbreeding depression
What ways can you control pathogens?
- Fungicides
- Chemotherapeutants
- Antibiotics
- Probiotics
What are the concerns for using antibiotics?
- usage has declined in past years
- Antibiotic resistance
- Residuals in harvested stock - food safety
What is meant by the term veterinary cascade?
Vets have a code of conduct to conserve species and animal lives
- Usage of antibiotics is frowned upon in aquaculture communities but vets can use them if it is the only thing that can help
What is the difference between pre- and probiotics?
Prebiotics - chemicals which create optimal conditions for bacterial growth
Probiotics - Actual bacteria
