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1Institute of Aquaculture - University of Stirling
Aquaculture
Royal Veterinary CollegeJanuary 2004Jimmy Turnbull
2Institute of Aquaculture - University of Stirling
Outline of the morning
Aquaculture Introduction to aquatic animal
healthAquatic animal disease diagnosis
and investigation Disease control and treatment
3Institute of Aquaculture - University of Stirling
What is aquaculture?
Fisheries are a form of hunting Aquaculture is a form of farming
Any type of aquatic animal or plant Seaweed, mussels, shrimps, fish,
crocodiles etc
4Institute of Aquaculture - University of Stirling
Aquaculture
Huge industry / source of livelihoods 75% of population in some of SE Asia
Very diverse Climate/Water source/Species/
Systems/IntensificationGreat opportunities to travel
5Institute of Aquaculture - University of Stirling
FAO 1995 Aquaculture = 23% of total aquatic prod.
Total aquatic production
Aquaculture
Fisheries
6Institute of Aquaculture - University of Stirling
FAO 1995
Fisheries declining, aquaculture fastest growing food production sector
Aquaculture produced nearly 28 million
tonnesAquaculture more important in
developing and LIFD countries
7Institute of Aquaculture - University of Stirling
FAO 1995
0
20
40
60
80
100
Million tonnes
Pigs Cattle Chickens Aquatic Sheep
Global meat production
8Institute of Aquaculture - University of Stirling
Aquaculture + and -
Exhausted wild catches Food production vs use of fish meal
Food security Low cost high quality food vs
export orientated production
Food safety High quality protein and lipid vs
chemical residues
Environment Sustainable resource vs pollution
9Institute of Aquaculture - University of Stirling
Size and value of aquaculture
UK Atlantic salmon industry 120,000 tonnes/year £300 million 1999
World production 472,000 tonnes/year
10Institute of Aquaculture - University of Stirling
Example - Salmon life cylce
Fresh water
Sea
11Institute of Aquaculture - University of Stirling
Value of ornamentals
World wholesale market £ 4,800 to 2,000 million
UK wholesale value £13 million (1994) UK retail value in
1990 = £203 million 1998 = £104.6 million
12Institute of Aquaculture - University of Stirling
Ornamental fish exporters
Europe
16% Asia
63%
Other
5%Americas
16%
13Institute of Aquaculture - University of Stirling
Ornamental fish importers
Asia
26%
Other
4%
Americas
33%Europe
37%
1st USA2nd Japan3rd Germany4th UK
14Institute of Aquaculture - University of Stirling
Value of ornamentals
Fish 3rd most popular pet after dogs and cats
35 to 40 million fish imported / year 1,000 tropical species <20 cold water species
Fish = 75% of airlines livestock income
15Institute of Aquaculture - University of Stirling
Role of vets in aquaculture
DiagnosticiansHealth management / managementResearchTraining / teachingGovernment animal health controlDevelopment
16Institute of Aquaculture - University of Stirling
Introduction to Aquatic Animal Health
Introduction to Aquatic Animal Health
JF TurnbullJF Turnbull
17Institute of Aquaculture - University of Stirling
Why Study Aquatic disease?Why Study Aquatic disease?
A ccademic int er est
Control losses Prevent losses
I ncrease profi tability / secure livelihoods
I ncrease product ion
W hy study disease?
18Institute of Aquaculture - University of Stirling
Costs of Poor HealthCosts of Poor Health
Loss of fish - mortalities Loss of production Loss of investor confidence Loss of opportunity Cost of control or
prevention Wild stock
Broodstock Fisheries
Loss of fish - mortalities Loss of production Loss of investor confidence Loss of opportunity Cost of control or
prevention Wild stock
Broodstock Fisheries
19Institute of Aquaculture - University of Stirling
Health management and the system
The health of aquatic animals is more related to their environment and husbandry than in terrestrial animals
Diagnosis and control depend on an understanding of system
20Institute of Aquaculture - University of Stirling
Unit of InterestUnit of Interest
Usually only interested in the population Not usually interested in the individual
Individuals only important as far as they relate to the population
Try to develop an idea of what is happening in the whole population
What is the population?
Usually only interested in the population Not usually interested in the individual
Individuals only important as far as they relate to the population
Try to develop an idea of what is happening in the whole population
What is the population?
21Institute of Aquaculture - University of Stirling
Unit of InterestUnit of Interest
Population can be : Ponds, cage or tank Farms Areas of a country A whole region
EPIDEMIOLOGY you should know about this already
Population can be : Ponds, cage or tank Farms Areas of a country A whole region
EPIDEMIOLOGY you should know about this already
22Institute of Aquaculture - University of Stirling
Host/Environment/PathogenHost/Environment/Pathogen
23Institute of Aquaculture - University of Stirling
EnvironmentEnvironment
What can cause stress = anything!!!!
For example : Environment or management Nutrition Behaviour Other diseases Treatments
What can cause stress = anything!!!!
For example : Environment or management Nutrition Behaviour Other diseases Treatments
24Institute of Aquaculture - University of Stirling
Host
Very wide range of species Salmon and carp more different than
dog and cow
25Institute of Aquaculture - University of Stirling
HostHost
Fish - inherent defences Normal microflora
Especially in the gut
Skin Stomach acid and gut
Carnivore vs herbivore
Fish - immunity Non-specific immunity Specific immunity
Fish - inherent defences Normal microflora
Especially in the gut
Skin Stomach acid and gut
Carnivore vs herbivore
Fish - immunity Non-specific immunity Specific immunity
26Institute of Aquaculture - University of Stirling
Fish Skin
27Institute of Aquaculture - University of Stirling
HostHost
Fish - Non-specific immunity Humoral - compounds in body
fluids Circulating cells Tissue-dwelling cells
Fish - Non-specific immunity Humoral - compounds in body
fluids Circulating cells Tissue-dwelling cells
28Institute of Aquaculture - University of Stirling
Host
Fish - Specific immunity Humoral - compounds in body
fluids Circulating cells
Lymphocytes - Antibody production Phagocytes - Phagocytosis and APC
29Institute of Aquaculture - University of Stirling
HostHost
Normal defences are labile, subject to Endogenous changes
Moulting in crustaceans Reproductive state, especially in salmonids
Skin, gut, cardiovascular, immune system Genetics - resistant strains not successful Immunity Immunomodulation
Normal defences are labile, subject to Endogenous changes
Moulting in crustaceans Reproductive state, especially in salmonids
Skin, gut, cardiovascular, immune system Genetics - resistant strains not successful Immunity Immunomodulation
30Institute of Aquaculture - University of Stirling
HostHost
Normal defences are labile, subject to Exogenous factors :
Nutrition Environment esp’ temperature
Degree days Growth Immune response Inflammation Healing - skin less affected Growth of tumours
Physical damage
Normal defences are labile, subject to Exogenous factors :
Nutrition Environment esp’ temperature
Degree days Growth Immune response Inflammation Healing - skin less affected Growth of tumours
Physical damage
31Institute of Aquaculture - University of Stirling
PathogensPathogens
Same range of infectious pathogens as in mammals
viruses bacteria fungi protozoa metazoa
Same range of infectious pathogens as in mammals
viruses bacteria fungi protozoa metazoa
32Institute of Aquaculture - University of Stirling
PathogenPathogen
Number of pathogens varies with : Number of sick animals Available nutrients
Access for pathogen to hosts Easier in aquatic environment
Terrestrial disease often in fluid blood, droplets, sexual
In aquaculture systems hosts concentrated
Number of pathogens varies with : Number of sick animals Available nutrients
Access for pathogen to hosts Easier in aquatic environment
Terrestrial disease often in fluid blood, droplets, sexual
In aquaculture systems hosts concentrated
33Institute of Aquaculture - University of Stirling
PathogenPathogen
34Institute of Aquaculture - University of Stirling
Pathogens
Examples WSD EUS Ich Salmon lice
35Institute of Aquaculture - University of Stirling
Cause WSSV and other factorsMassive impact
US$600 million in Thailand in 1997Affects all systems
Extensive to Intensive
White Spot Disease (WSD)e (WSD)
36Institute of Aquaculture - University of Stirling
E.U.S. outbreaksE.U.S. outbreaks
1972
1983
1972
1988
1998
37Institute of Aquaculture - University of Stirling
Aphanomyces invaderens
38Institute of Aquaculture - University of Stirling
Non-infectious DiseaseNon-infectious Disease Nutritional
Proportion of nutrients e.g. Ca / P Deficiencies e.g. hypovitaminosis or malnutrition Excesses of nutrient e.g. hypervitaminosis Toxic compounds e.g. rancid fats, fungal toxins
etc. Environmental
Too much e.g. ammonia Too little e.g. O2
Genetic/congenital Increased susceptibility to infections
Nutritional Proportion of nutrients e.g. Ca / P Deficiencies e.g. hypovitaminosis or malnutrition Excesses of nutrient e.g. hypervitaminosis Toxic compounds e.g. rancid fats, fungal toxins
etc. Environmental
Too much e.g. ammonia Too little e.g. O2
Genetic/congenital Increased susceptibility to infections
39Institute of Aquaculture - University of Stirling
Why deal with populations?
Lab’ experiments cannot be generalised to the farm Level of immune stimulation
Will differ between lab’ and farm Field challenges may (will) differ from
experimental challenges May be unpredictable effects
40Institute of Aquaculture - University of Stirling
Why deal with populations? (continued)
Large populations have inherent and unpredictable dynamics as a result of :
Sum of individual variation in: Non-specific defence mechanisms Response to stress, Level of pre-existing
immunostimulation Inherent population effects including :
Proportion infected and Rate of transmission
41Institute of Aquaculture - University of Stirling
Why deal with populations?
Without field trial data You cannot advise on :
The magnitude of any benefits vs costs How to use treatment for best results
The treatment is a gamble Improved chance of success or Another cost with no return
42Institute of Aquaculture - University of Stirling
Aquatic animal disease Diagnosis and Investigation
Jimmy Turnbull
43Institute of Aquaculture - University of Stirling
Diagnoses
Need to look at a range of information
Clinical signs e.g. behaviour, appearance Production information Laboratory information e.g.
Fresh preparations Bacteriology Virology Histology Parasitology & others
44Institute of Aquaculture - University of Stirling
Standard Growth Curve and Tolerance
45Institute of Aquaculture - University of Stirling
Standard Growth Curve and Tolerance
46Institute of Aquaculture - University of Stirling
Problems with diagnosis!
Identifying aquatic health is difficult Cannot see the animals
Abnormal behaviour Mortalities
Feeding often only time to observe Clinical signs not much use
47Institute of Aquaculture - University of Stirling
Problems with diagnosis!
Clinical signs / examination not very useful Farmers may use CS to spot a
problem Cannot often use CS to diagnose a
problem Aquatic animals limited capacity to express CS Same CS different disease or same disease
different CS
48Institute of Aquaculture - University of Stirling
DiagnosisDiagnosis
Very similar to terrestrial animals
Identify and determine cause of problem Presented information - often misleading History PATTERN OF THE DISEASE
Species / age / No affected / Groups affected / Onset / Duration / Clinical signs / Previous diseases / Treatments
General farm information
Very similar to terrestrial animals
Identify and determine cause of problem Presented information - often misleading History PATTERN OF THE DISEASE
Species / age / No affected / Groups affected / Onset / Duration / Clinical signs / Previous diseases / Treatments
General farm information
49Institute of Aquaculture - University of Stirling
Patterns of disease
Patterns one of the most important aspects Should lead to useful interventions
Spread over time and geographically Associations with :
Environmental events Batches of seed Batches of feed
50Institute of Aquaculture - University of Stirling
Patterns of disease
Sudden acute sever mortality - CAUSES?
Infectious problems - PATTERN? Propagating Point-source
Nutritional problems - PATTERN? Associations with risk factors
51Institute of Aquaculture - University of Stirling
Significance of diagnosisSignificance of diagnosis
Significance of the diagnosis Are there other problems? Which is the most important of the
problems? What is the underlying cause? What is the impact of the disease
On profitability On livelihood
Significance of the diagnosis Are there other problems? Which is the most important of the
problems? What is the underlying cause? What is the impact of the disease
On profitability On livelihood
52Institute of Aquaculture - University of Stirling
Methods to identify pathogensMethods to identify pathogens
All techniques used to identify pathogens have some very serious practical limitations Cannot sample a large enough
proportion of the animals Difficult to get representative samples Test always have limitations
All techniques used to identify pathogens have some very serious practical limitations Cannot sample a large enough
proportion of the animals Difficult to get representative samples Test always have limitations
53Institute of Aquaculture - University of Stirling
Diagnostic tests - no such thing!
There are tests to identify pathogens BUT the presence of the pathogen is not
the same as the presence of the disease
Few tests compared to terrestrial animals
54Institute of Aquaculture - University of Stirling
Methods to identify pathogens
Methods to identify pathogens
How many do you sample? < 1g = 10+ > 1g =6 ‘ish
PCR pls. approx’ 100
How do you obtain the fish or shrimp? Random sample e.g. from cast net Selected sample from sick
How many do you sample? < 1g = 10+ > 1g =6 ‘ish
PCR pls. approx’ 100
How do you obtain the fish or shrimp? Random sample e.g. from cast net Selected sample from sick
55Institute of Aquaculture - University of Stirling
Methods to identify pathogensMethods to identify pathogens
Test limitations False negatives (sensitivity) False positives (specificity) Best tests including PCR
95% sensitive and specific Get 5% false negatives and 5% false
positives
Test limitations False negatives (sensitivity) False positives (specificity) Best tests including PCR
95% sensitive and specific Get 5% false negatives and 5% false
positives
56Institute of Aquaculture - University of Stirling
Health Control and Treatment
JF Turnbull
57Institute of Aquaculture - University of Stirling
Course of actionCourse of action
Do nothing May not be acceptable
Change management!!!!!!!!!!!
Kill fish Loss or emergency harvest Insurance and welfare
TREATMENT
Do nothing May not be acceptable
Change management!!!!!!!!!!!
Kill fish Loss or emergency harvest Insurance and welfare
TREATMENT
58Institute of Aquaculture - University of Stirling
Management changes
May be all that is possible
Increase oxygenation Reduce exposure to carriers Improve hygiene
59Institute of Aquaculture - University of Stirling
Cost benefit analysesCost benefit analyses
Cost of Drug Labour Lost production Withdrawal periods Mortalities resulting from
treatment Efficacy of treatment Political / legal and ethical
considerations
Verses benefit of treatmentRe-consider course of action
Cost of Drug Labour Lost production Withdrawal periods Mortalities resulting from
treatment Efficacy of treatment Political / legal and ethical
considerations
Verses benefit of treatmentRe-consider course of action
60Institute of Aquaculture - University of Stirling
Cost benefit analyses 2/2Disease problem
Diagnosis Significance
Course of Action1. Nothing2. Change management3. Kill fish4. Treatment
Drug MethodCost benefit analyses
ACTION
61Institute of Aquaculture - University of Stirling
Treatment - general precautions
Treatment - general precautions
Check fish health Starve fish Trial therapy Check calculations Mix drug adequately
Beware of stock solutions
Ensure adequate O2
Dispose of waste carefully
Check fish health Starve fish Trial therapy Check calculations Mix drug adequately
Beware of stock solutions
Ensure adequate O2
Dispose of waste carefully
62Institute of Aquaculture - University of Stirling
TreatmentTreatment
Drug?Method of treatment?
Drug?Method of treatment?
63Institute of Aquaculture - University of Stirling
Types of treatmentTypes of treatment
Immersion Flowing Flush Dip Bath
Immersion Flowing Flush Dip Bath
64Institute of Aquaculture - University of Stirling
Immersion
Flowing
Flush
65Institute of Aquaculture - University of Stirling
Bath Treatment in cages
66Institute of Aquaculture - University of Stirling
No containment
Fish movement
Water currents
67Institute of Aquaculture - University of Stirling
Curtain 1/3
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Curtain 2/3
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Curtain 3/3
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Full bag 1/6
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Full bag 2/6
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Full bag 3/6
73Institute of Aquaculture - University of Stirling
Full bag 4/6
74Institute of Aquaculture - University of Stirling
Full bag 5/6
75Institute of Aquaculture - University of Stirling
Full bag 6/6
76Institute of Aquaculture - University of Stirling
Bath treatmentBath treatment
If it goes wrong Increase aeration Dilute drug or allow fish to escape from drug
Increase volumeIncrease flow
If it goes wrong Increase aeration Dilute drug or allow fish to escape from drug
Increase volumeIncrease flow
77Institute of Aquaculture - University of Stirling
Types of treatmentTypes of treatment
In feed Usually antibiotics Reduce total feed and top up if necessary Medicated food spread throughout the
day Mixing
Surface coating Incorporation at mill
Volume Time
In feed Usually antibiotics Reduce total feed and top up if necessary Medicated food spread throughout the
day Mixing
Surface coating Incorporation at mill
Volume Time
78Institute of Aquaculture - University of Stirling
Types of treatmentTypes of treatment
Topical Injection
Topical Injection
79Institute of Aquaculture - University of Stirling
Thank you
http://staff.stir.ac.uk/j.f.turnbull/
80Institute of Aquaculture - University of Stirling
http://www.aquaculture.stir.ac.uk
These lectures and other links are on
http://staff.stir.ac.uk/j.f.turnbull/