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Flashcards in Food technology 4 Deck (107)
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Outline welfare in fish production

- No inherent factors in fish farming that result in inevitable poor welfare
- Only where poorly run
- 6 key stressors in aquaculture environment


What are the 6 key stressors in aquaculture?

- Water quality
- Crowding
- handling
- Disturbance
- Nutrition
- Hierarchy


How may water quality lead to stress in farmed fish?

Contaminated water can make it hard to breathe


How may crowding lead to stress in farmed fish?

Intense crowding can result in cannibalism


How may handling lead to stress in farmed fish?

Invasive handling results in stress and poor health


How may nutrition lead to stress in farmed fish?

Nutritional deficiencies can weaken the immune system and affect development e.g. spinal deformities


How may hierarchy lead to stress in farmed fish?

If unable to form a stable social hierarchy e.g. due to frequent mixing, can result in cannibalism


How is maximum survival and maintenance of healthy fish stocks primarily achieved?

- Good husbandry and health management practices and policies
- Reduce exposure to pathogens and risk of health challenges


How can diseases be prevented in fish?

- Vaccination at early stages of development
- Medicinal treatment in some instances to maximise survival
- However for several diseases no effective vaccines are currently available


List the common salmon diseases

- Sea lice
- Pancreas Disease (PD)
- Salmonid Rickettsial Septicaemia (SRS)
- Infectious Pancreatic Necrosis (IPN virus)
- Heart and Skeletal Muscle inflammation (HSM)
- Infectious Salmon Anaemia (ISA)
- Gill Disease (GD)


Outline sea lice

- Several species
- Sea water
- Can cause lesions, secondary bacterial infections
- Controlled through good husbandry, management, use of cleaner fish
- Where necessary, licensed medicines


Outline Pancreas Disease in salmon

- Salmonid Alphavirus (present in Europe)
- Contagious
- Reduces appetite, causes muscle and pancreas lesions, lethargy, elevated mortality
- Seawater
- Affects Atlantic salmon and Rainbow trout


Outline the control of Pancreas disease

- Management and mitigation practices
- Vaccination where PD presents risk, provides some additional level of protection


Outline Salmonid Rickettsial Septicaemia

- Intracellular bacteria
- Mainly Chile, also Norway, Ireland, UK
- Lethargy, appetite loss, elevated mortality


Outline the control of Salmonid Rickettsial Septicaemia

- Vaccination
- Licensed antibiotics


Outline Infectious Pancreatic Necrosis in salmon

- Widely reported
- Contagious
- Mortality if not properly managed
- Atlantic salmon fry, smolts and larger fish post-transfer affected


Outline the control of Infectious Pancreatic Necrosis

- Vaccination
- Optimise husbandry and biosecurity
- Selection of IPN resistant fish


Outline Heart and Skeletal Muscle Inflammation in salmon

- Norway and Scotland
- Reduced appetite, abnormal behaviour
- But low mortality
- generally affects fish in first year in seawater


Outline the control of Heart and Skeletal Muscle Inflammation

Good husbandry and management practices


Outline Infectious Salmon Anaemia (ISA)

- Virus
- Contagious
- Causes lethargy, anaemia and significant mortality in seawater with poor management


Outline the control of ISA

- Vaccines in high risk areas
- Culling or harvesting of affected fish
- Other biosecurity and mitigation measures


Outline Gill Disease in salmon

- Any gill condition occurring in seawater
- Changes caused by different infectious agents e.g. amoeba, virus, bacteria
- Also environmental factors e.g. algae, jelly-fish blooms
- Little known about cause and to what extend infectious or environmental factors are primary or secondary to cause of disease


List environmental impacts associated with aquaculture

- Water abstraction
- Suspended solids/organic loading
- Reduced O2
- Nitrogenous waste products
- Chemicals/drugs
- Spread of enzootic pathogens
- introduction/movement of alien species
- Genetic contamination
- Water quality and density
- Sea lice


Outline water abstraction by fish production

depending on production size and size, large proportions of water may be extracted from natural sources


Outline how fish production increases suspended solids/organic loading

Water returning to natural water systems will contain higher proportions of organic matter


Outline how fish production affects the presence of nitrogenous waste products in water

Large populations of fish can result in higher levels of nitrogen in water and eutrophication


Outline the effects of fish production on the presence of chemicals/drugs in water

Residues of drugs/chemicals used in fish farming could be present in water ad contaminate the environment


Outline how fish production may lead to the spread of enzootic pathogens

- Possibility that having increased fish population in area may favour the spread of enzootic diseases
- No strong evidence supporting this except for sea lice


Outline the effects of fish production with regards to alien species

- Large scale movement of animals between countries into non-native area
- Higher risk of spreading fish diseases globally
- Introduction of new diseases


Outline the effects of fish production on genetic contamination

Evidence of reduced genetic variability in salmon due to interbreeding between farmed and wild salmon