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Aquaculture Royal Veterinary College January 2004 Jimmy Turnbull Institute of Aquaculture - University of Stirling 1 Outline of the morning Aquaculture Introduction to aquatic animal health Aquatic animal disease diagnosis and investigation Disease control and treatment Institute of Aquaculture - University of Stirling 2 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 Institute of Aquaculture - University of Stirling 3 Aquaculture Huge 75% of population in some of SE Asia Very industry / source of livelihoods diverse Climate/Water source/Species/ Systems/Intensification Great opportunities to travel Institute of Aquaculture - University of Stirling 4 FAO 1995 Aquaculture = 23% of total aquatic prod. Total aquatic production Fisheries Aquaculture Institute of Aquaculture - University of Stirling 5 FAO 1995 Fisheries declining, aquaculture fastest growing food production sector Aquaculture produced nearly 28 million tonnes Aquaculture more important in developing and LIFD countries Institute of Aquaculture - University of Stirling 6 FAO 1995 Global meat production 100 80 Million tonnes 60 40 20 0 Pigs Cattle Chickens Aquatic Institute of Aquaculture - University of Stirling Sheep 7 Aquaculture + and Exhausted Food production vs use of fish meal Food security Low cost high quality food vs export orientated production Food wild catches safety High quality protein and lipid vs chemical residues Environment Sustainable resource vs pollution Institute of Aquaculture - University of Stirling 8 Size and value of aquaculture UK Atlantic salmon industry 120,000 tonnes/year £300 million 1999 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 World £ 4,800 to 2,000 million UK wholesale market wholesale value £13 million (1994) UK retail value in 1990 = £203 million 1998 = £104.6 million Institute of Aquaculture - University of Stirling 11 Ornamental fish exporters Other Americas 5% 16% Europe 16% Institute of Aquaculture - University of Stirling Asia 63% 12 Ornamental fish importers Americas 33% Europe 37% Other 1st 2nd 3rd 4th USA Japan Germany UK 4% Asia 26% Institute of Aquaculture - University of Stirling 13 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 Institute of Aquaculture - University of Stirling 14 Role of vets in aquaculture Diagnosticians Health management / management Research Training / teaching Government animal health control 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? Why study disease? Accademic interest Prevent losses Control losses Increase production Increase profitability / secure livelihoods Institute of Aquaculture - University of Stirling 17 Costs 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 Institute of Aquaculture - University of Stirling 18 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 Institute of Aquaculture - University of Stirling 19 Unit 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? Institute of Aquaculture - University of Stirling 20 Unit of Interest Population can be : Ponds, cage or tank Farms Areas of a country A whole region 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 What can cause stress = anything!!!! For example : Environment or management Nutrition Behaviour Other diseases Treatments Institute of Aquaculture - University of Stirling 23 Host Very wide range of species Salmon and carp more different than dog and cow Institute of Aquaculture - University of Stirling 24 Host Fish - inherent defences Normal microflora Skin Stomach acid and gut Especially in the gut Carnivore vs herbivore Fish - immunity Non-specific immunity Specific immunity Institute of Aquaculture - University of Stirling 25 Fish Skin Institute of Aquaculture - University of Stirling 26 Host Fish - Non-specific immunity Humoral - compounds in body fluids Circulating cells Tissue-dwelling cells Institute of Aquaculture - University of Stirling 27 Host Fish - Specific immunity Humoral - compounds in body fluids Circulating cells Lymphocytes - Antibody production Phagocytes - Phagocytosis and APC Institute of Aquaculture - University of Stirling 28 Host 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 Institute of Aquaculture - University of Stirling 29 Host 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 Institute of Aquaculture - University of Stirling 30 Pathogens Same range of infectious pathogens as in mammals viruses bacteria fungi protozoa metazoa Institute of Aquaculture - University of Stirling 31 Pathogen Number of pathogens varies with : Number of sick animals Available nutrients Access Easier in aquatic environment Terrestrial disease often in fluid 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 Examples WSD EUS Ich Salmon lice Institute of Aquaculture - University of Stirling 34 White Spot Disease (WSD) Cause WSSV and other factors Massive impact US$600 million in Thailand in 1997 Affects all systems Extensive to Intensive Institute of Aquaculture - University of Stirling 35 E.U.S. outbreaks 1972 1998 1988 1983 1972 Institute of Aquaculture - University of Stirling 36 Aphanomyces Institute of Aquaculture - University of Stirling invaderens 37 Non-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 Institute of Aquaculture - University of Stirling 38 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 Institute of Aquaculture - University of Stirling 39 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 Institute of Aquaculture - University of Stirling 40 Why deal with populations? Without You cannot advise on : field trial data 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 Institute of Aquaculture - University of Stirling 41 Aquatic animal disease Diagnosis and Investigation Jimmy Turnbull Institute of Aquaculture - University of Stirling 42 Diagnoses Need to look at a range of information signs e.g. behaviour, appearance Production information Laboratory information e.g. Clinical Fresh preparations Bacteriology Virology Histology Parasitology & others Institute of Aquaculture - University of Stirling 43 Standard Growth Curve and Tolerance Standard Growth Curve & Tolerance 50 45 40 ABW (g) 35 30 25 20 15 10 5 0 1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 Days of Culture Institute of Aquaculture - University of Stirling 44 Standard Growth Curve and Tolerance Average Growth (AA) 35.00 30.00 ABW (g) 25.00 20.00 15.00 10.00 5.00 0.00 30 37 44 51 58 65 72 79 86 93 100 107 114 121 128 135 142 DOC Institute of Aquaculture - University of Stirling 45 Problems with diagnosis! Identifying Cannot see the animals 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! 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 Institute of Aquaculture - University of Stirling 47 Diagnosis 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 Institute of Aquaculture - University of Stirling 48 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 Institute of Aquaculture - University of Stirling 49 Patterns of disease Sudden acute sever mortality - CAUSES? Infectious problems - PATTERN? Propagating Point-source Nutritional problems - PATTERN? Associations with risk factors Institute of Aquaculture - University of Stirling 50 Significance 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 Institute of Aquaculture - University of Stirling 51 Methods 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 Institute of Aquaculture - University of Stirling 52 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 Institute of Aquaculture - University of Stirling 53 Methods to identify pathogens How many do you sample? PCR < 1g = 10+ > 1g =6 ‘ish pls. approx’ 100 How 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 Test limitations False negatives (sensitivity) False positives (specificity) Best tests including PCR 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 Do nothing May not be acceptable Change Kill management!!!!!!!!!!! fish Loss or emergency harvest Insurance and welfare TREATMENT Institute of Aquaculture - University of Stirling 57 Management changes May be all that is possible Increase oxygenation Reduce exposure to carriers Improve hygiene Institute of Aquaculture - University of Stirling 58 Cost 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 treatment 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 Check fish health Starve fish Trial therapy Check calculations Mix drug adequately Beware of stock solutions Ensure adequate O2 Dispose of waste carefully Institute of Aquaculture - University of Stirling 61 Treatment Drug? Method of treatment? Institute of Aquaculture - University of Stirling 62 Types of treatment Immersion 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 If it goes wrong Increase aeration Dilute drug or allow fish to escape from drug Increase volume Increase flow Institute of Aquaculture - University of Stirling 76 Types 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 Institute of Aquaculture - University of Stirling 77 Types of treatment Topical 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