Aquaculture Royal Veterinary College January 2004 Jimmy Turnbull
Aquaculture Royal Veterinary College January 2004 Jimmy Turnbull Institute of Aquaculture - University of Stirling 1
Outline of the morning u Aquaculture u Introduction to aquatic animal health u Aquatic animal disease diagnosis and investigation u Disease control and treatment Institute of Aquaculture - University of Stirling 2
What is aquaculture? u Fisheries are a form of hunting u Aquaculture is a form of farming u u Any type of aquatic animal or plant Seaweed, mussels, shrimps, fish, crocodiles etc Institute of Aquaculture - University of Stirling 3
Aquaculture u Huge u 75% of population in some of SE Asia u Very u industry / source of livelihoods diverse Climate/Water source/Species/ Systems/Intensification u Great opportunities to travel Institute of Aquaculture - University of Stirling 4
FAO 1995 u Aquaculture = 23% of total aquatic prod. Institute of Aquaculture - University of Stirling 5
FAO 1995 u Fisheries declining, aquaculture fastest growing food production sector u Aquaculture produced nearly 28 million tonnes u Aquaculture more important in developing and LIFD countries Institute of Aquaculture - University of Stirling 6
FAO 1995 Institute of Aquaculture - University of Stirling 7
Aquaculture + and u Exhausted u Food production vs use of fish meal u Food u security Low cost high quality food vs export orientated production u Food u wild catches safety High quality protein and lipid vs chemical residues u Environment u Sustainable resource vs pollution Institute of Aquaculture - University of Stirling 8
Size and value of aquaculture u UK u u Atlantic salmon industry 120, 000 tonnes/year £ 300 million 1999 u World production 472, 000 tonnes/year Institute of Aquaculture - University of Stirling 9
Example - Salmon life cylce Sea Fresh water Institute of Aquaculture - University of Stirling 10
Value of ornamentals u World u £ 4, 800 to 2, 000 million u UK u u wholesale market wholesale value £ 13 million (1994) UK retail value in 1990 = £ 203 million u 1998 = £ 104. 6 million u Institute of Aquaculture - University of Stirling 11
Institute of Aquaculture - University of Stirling 12
1 st 2 nd 3 rd 4 th USA Japan Germany UK Institute of Aquaculture - University of Stirling 13
Value of ornamentals u Fish 3 rd most popular pet after dogs and cats u 35 u u to 40 million fish imported / year 1, 000 tropical species <20 cold water species u Fish = 75% of airlines livestock income Institute of Aquaculture - University of Stirling 14
Role of vets in aquaculture u Diagnosticians u Health management / management u Research u Training / teaching u Government animal health control u Development Institute of Aquaculture - University of Stirling 15
Introduction to Aquatic Animal Health JF Turnbull Institute of Aquaculture - University of Stirling 16
Why Study Aquatic disease? Institute of Aquaculture - University of Stirling 17
Costs of Poor Health u u u Loss of fish - mortalities Loss of production Loss of investor confidence Loss of opportunity Cost of control or prevention Wild stock u u Broodstock Fisheries Institute of Aquaculture - University of Stirling 18
Health management and the system u The health of aquatic animals is more related to their environment and husbandry than in terrestrial animals u Diagnosis and control depend on an understanding of system Institute of Aquaculture - University of Stirling 19
Unit of Interest u Usually u only interested in the population Not usually interested in the individual Individuals only important as far as they relate to the population u Try to develop an idea of what is happening in the whole population u u What is the population? Institute of Aquaculture - University of Stirling 20
Unit of Interest u Population can be : Ponds, cage or tank u Farms u Areas of a country u A whole region u u EPIDEMIOLOGY you should know about this already Institute of Aquaculture - University of Stirling 21
Host/Environment/Pathogen Institute of Aquaculture - University of Stirling 22
Environment u What can cause stress = anything!!!! u For example : u u u Environment or management Nutrition Behaviour Other diseases Treatments Institute of Aquaculture - University of Stirling 23
Host u Very u wide range of species Salmon and carp more different than dog and cow Institute of Aquaculture - University of Stirling 24
Host u Fish - inherent defences u Normal microflora u u u Skin Stomach acid and gut u u Especially in the gut Carnivore vs herbivore Fish - immunity u u Non-specific immunity Specific immunity Institute of Aquaculture - University of Stirling 25
Fish Skin Institute of Aquaculture - University of Stirling 26
Host u Fish - Non-specific immunity u u u Humoral - compounds in body fluids Circulating cells Tissue-dwelling cells Institute of Aquaculture - University of Stirling 27
Host u Fish - Specific immunity u u Humoral - compounds in body fluids Circulating cells u Lymphocytes - Antibody production u Phagocytes - Phagocytosis and APC Institute of Aquaculture - University of Stirling 28
Host u Normal defences are labile, subject to u Endogenous changes u Moulting in crustaceans u Reproductive state, especially in salmonids u Skin, gut, cardiovascular, immune system u Genetics - resistant strains not successful u Immunity u Immunomodulation Institute of Aquaculture - University of Stirling 29
Host u Normal defences are labile, subject to u Exogenous factors : u Nutrition u Environment esp’ temperature u Degree days u Growth u Immune response u Inflammation u Healing - skin less affected u Growth of tumours u Physical damage Institute of Aquaculture - University of Stirling 30
Pathogens u Same range of infectious pathogens as in mammals u u u viruses bacteria fungi protozoa metazoa Institute of Aquaculture - University of Stirling 31
Pathogen u Number of pathogens varies with : u u Number of sick animals Available nutrients u Access u Easier in aquatic environment u Terrestrial disease often in fluid u u for pathogen to hosts blood, droplets, sexual In aquaculture systems hosts concentrated Institute of Aquaculture - University of Stirling 32
Pathogen Institute of Aquaculture - University of Stirling 33
Pathogens u. Examples u WSD u EUS u Ich u Salmon lice Institute of Aquaculture - University of Stirling 34
White Spot Disease (WSD) u Cause WSSV and other factors u Massive impact US$600 million in Thailand in 1997 u Affects all systems Extensive to Intensive Institute of Aquaculture - University of Stirling 35
E. U. S. outbreaks 1972 1998 1983 1972 Institute of Aquaculture - University of Stirling 36
u. Aphanomyces Institute of Aquaculture - University of Stirling invaderens 37
Non-infectious Disease u Nutritional u Proportion of nutrients e. g. Ca / P u Deficiencies e. g. hypovitaminosis or malnutrition u Excesses of nutrient e. g. hypervitaminosis u Toxic compounds e. g. rancid fats, fungal toxins etc. u Environmental u Too much e. g. ammonia u Too little e. g. O 2 Genetic/congenital u Increased susceptibility to infections u Institute of Aquaculture - University of Stirling 38
Why deal with populations? u Lab’ experiments cannot be generalised to the farm u Level of immune stimulation u u u Will differ between lab’ and farm Field challenges may (will) differ from experimental challenges May be unpredictable effects Institute of Aquaculture - University of Stirling 39
Why deal with populations? u (continued) u Large populations have inherent and unpredictable dynamics as a result of : u Sum of individual variation in: u u Non-specific defence mechanisms Response to stress, Level of pre-existing immunostimulation Inherent population effects including : u u Proportion infected and Rate of transmission Institute of Aquaculture - University of Stirling 40
Why deal with populations? u Without u You cannot advise on : u u u field trial data The magnitude of any benefits vs costs How to use treatment for best results The treatment is a gamble u u Improved chance of success or Another cost with no return Institute of Aquaculture - University of Stirling 41
Aquatic animal disease Diagnosis and Investigation Jimmy Turnbull Institute of Aquaculture - University of Stirling 42
Diagnoses u Need to look at a range of information u. Clinical signs e. g. behaviour, appearance u. Production information u Laboratory information e. g. w w w Fresh preparations Bacteriology Virology Histology Parasitology & others Institute of Aquaculture - University of Stirling 43
Standard Growth Curve and Tolerance Institute of Aquaculture - University of Stirling 44
Standard Growth Curve and Tolerance Institute of Aquaculture - University of Stirling 45
Problems with diagnosis! u Identifying u Cannot see the animals u u aquatic health is difficult Abnormal behaviour Mortalities Feeding often only time to observe Clinical signs not much use Institute of Aquaculture - University of Stirling 46
Problems with diagnosis! u Clinical u u signs / examination not very useful Farmers may use CS to spot a problem Cannot often use CS to diagnose a problem u u Aquatic animals limited capacity to express CS Same CS different disease or same disease different CS Institute of Aquaculture - University of Stirling 47
Diagnosis u Very u u u 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 u General farm information u Institute of Aquaculture - University of Stirling 48
Patterns of disease u Patterns one of the most important aspects u Should lead to useful interventions u u Spread over time and geographically Associations with : u u u Environmental events Batches of seed Batches of feed Institute of Aquaculture - University of Stirling 49
Patterns of disease u Sudden acute sever mortality - CAUSES? u Infectious problems - PATTERN? u u Propagating Point-source u Nutritional problems - PATTERN? u Associations with risk factors Institute of Aquaculture - University of Stirling 50
Significance of diagnosis u Significance u u 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 u u On profitability On livelihood Institute of Aquaculture - University of Stirling 51
Methods to identify pathogens u All techniques used to identify pathogens have some very serious practical limitations u u u Cannot sample a large enough proportion of the animals Difficult to get representative samples Test always have limitations Institute of Aquaculture - University of Stirling 52
Diagnostic tests - no such thing! u There u are tests to identify pathogens BUT the presence of the pathogen is not the same as the presence of the disease u Few tests compared to terrestrial animals Institute of Aquaculture - University of Stirling 53
Methods to identify pathogens u How u u many do you sample? < 1 g = 10+ > 1 g =6 ‘ish u PCR u pls. approx’ 100 u How u u do you obtain the fish or shrimp? Random sample e. g. from cast net Selected sample from sick Institute of Aquaculture - University of Stirling 54
Methods to identify pathogens u Test u u u limitations False negatives (sensitivity) False positives (specificity) Best tests including PCR u u 95% sensitive and specific Get 5% false negatives and 5% false positives Institute of Aquaculture - University of Stirling 55
Health Control and Treatment JF Turnbull Institute of Aquaculture - University of Stirling 56
Course of action u Do u nothing May not be acceptable u Change u Kill u u management!!!!!! fish Loss or emergency harvest Insurance and welfare u TREATMENT Institute of Aquaculture - University of Stirling 57
Management changes u May u u u be all that is possible Increase oxygenation Reduce exposure to carriers Improve hygiene Institute of Aquaculture - University of Stirling 58
Cost benefit analyses u Cost of u u u u Drug Labour Lost production Withdrawal periods Mortalities resulting from treatment Efficacy of treatment Political / legal and ethical considerations Verses benefit of treatment u Re-consider course of action Institute of Aquaculture - University of Stirling 59
Cost benefit analyses 2/2 Disease problem Diagnosis Significance Course of Action 1. Nothing 2. Change management 3. Kill fish 4. Treatment Drug Method Cost benefit analyses ACTION Institute of Aquaculture - University of Stirling 60
Treatment - general precautions u Check fish health u Starve fish u Trial therapy u Check calculations u Mix drug adequately u Beware of stock solutions u Ensure adequate O 2 u Dispose of waste carefully Institute of Aquaculture - University of Stirling 61
Treatment u Drug? u Method of treatment? Institute of Aquaculture - University of Stirling 62
Types of treatment u Immersion u u Flowing Flush Dip Bath Institute of Aquaculture - University of Stirling 63
Immersion Flowing Flush Institute of Aquaculture - University of Stirling 64
Bath Treatment in cages Institute of Aquaculture - University of Stirling 65
No containment Fish movement Water currents Institute of Aquaculture - University of Stirling 66
Curtain 1/3 Institute of Aquaculture - University of Stirling 67
Curtain 2/3 Institute of Aquaculture - University of Stirling 68
Curtain 3/3 Institute of Aquaculture - University of Stirling 69
Full bag 1/6 Institute of Aquaculture - University of Stirling 70
Full bag 2/6 Institute of Aquaculture - University of Stirling 71
Full bag 3/6 Institute of Aquaculture - University of Stirling 72
Full bag 4/6 Institute of Aquaculture - University of Stirling 73
Full bag 5/6 Institute of Aquaculture - University of Stirling 74
Full bag 6/6 Institute of Aquaculture - University of Stirling 75
Bath treatment u If u u it goes wrong Increase aeration Dilute drug or allow fish to escape from drug u. Increase volume u. Increase flow Institute of Aquaculture - University of Stirling 76
Types of treatment u In u u feed Usually antibiotics Reduce total feed and top up if necessary Medicated food spread throughout the day Mixing u Surface coating u Incorporation at mill u u Volume Time Institute of Aquaculture - University of Stirling 77
Types of treatment u Topical u Injection Institute of Aquaculture - University of Stirling 78
Thank you http: //staff. stir. ac. uk/j. f. turnbull/ Institute of Aquaculture - University of Stirling 79
http: //www. aquaculture. stir. ac. uk These lectures and other links are on http: //staff. stir. ac. uk/j. f. turnbull/ Institute of Aquaculture - University of Stirling 80
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