1 Institute of Aquaculture - University of Stirling Aquaculture Royal Veterinary College January 2004 Jimmy Turnbull

2 Institute of Aquaculture - University of Stirling Outline of the morning  Aquaculture  Introduction to aquatic animal health  Aquatic animal disease diagnosis and investigation  Disease control and treatment

3 Institute 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

4 Institute 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/Intensification  Great opportunities to travel

5 Institute of Aquaculture - University of Stirling FAO 1995  Aquaculture = 23% of total aquatic prod.

6 Institute of Aquaculture - University of Stirling FAO 1995  Fisheries declining, aquaculture fastest growing food production sector  Aquaculture produced nearly 28 million tonnes  Aquaculture more important in developing and LIFD countries

7 Institute of Aquaculture - University of Stirling FAO 1995

8 Institute 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

9 Institute 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

10 Institute of Aquaculture - University of Stirling Example - Salmon life cylce Fresh water Sea

11 Institute 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

12 Institute of Aquaculture - University of Stirling

13 Institute of Aquaculture - University of Stirling 1 st USA 2 nd Japan 3 rd Germany 4 th UK

14 Institute of Aquaculture - University of Stirling Value of ornamentals  Fish 3 rd 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

15 Institute of Aquaculture - University of Stirling Role of vets in aquaculture  Diagnosticians  Health management / management  Research  Training / teaching  Government animal health control  Development

16 Institute of Aquaculture - University of Stirling Introduction to Aquatic Animal Health JF Turnbull

17 Institute of Aquaculture - University of Stirling Why Study Aquatic disease?

18 Institute of Aquaculture - University of Stirling 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

19 Institute 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

20 Institute of Aquaculture - University of Stirling 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?

21 Institute of Aquaculture - University of Stirling 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

22 Institute of Aquaculture - University of Stirling Host/Environment/Pathogen

23 Institute of Aquaculture - University of Stirling Environment  What can cause stress = anything!!!!  For example :  Environment or management  Nutrition  Behaviour  Other diseases  Treatments

24 Institute of Aquaculture - University of Stirling Host  Very wide range of species  Salmon and carp more different than dog and cow

25 Institute of Aquaculture - University of Stirling Host  Fish - inherent defences  Normal microflora  Especially in the gut  Skin  Stomach acid and gut  Carnivore vs herbivore  Fish - immunity  Non-specific immunity  Specific immunity

26 Institute of Aquaculture - University of Stirling Fish Skin

27 Institute of Aquaculture - University of Stirling Host  Fish - Non-specific immunity  Humoral - compounds in body fluids  Circulating cells  Tissue-dwelling cells

28 Institute of Aquaculture - University of Stirling Host  Fish - Specific immunity  Humoral - compounds in body fluids  Circulating cells  Lymphocytes - Antibody production  Phagocytes - Phagocytosis and APC

29 Institute of Aquaculture - University of Stirling 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

30 Institute of Aquaculture - University of Stirling 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

31 Institute of Aquaculture - University of Stirling Pathogens  Same range of infectious pathogens as in mammals  viruses  bacteria  fungi  protozoa  metazoa

32 Institute of Aquaculture - University of Stirling Pathogen  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

33 Institute of Aquaculture - University of Stirling Pathogen

34 Institute of Aquaculture - University of Stirling Pathogens  Examples  WSD  EUS  Ich  Salmon lice

35 Institute of Aquaculture - University of Stirling  Cause WSSV and other factors  Massive impact US$600 million in Thailand in 1997  Affects all systems Extensive to Intensive e (WSD) White Spot Disease (WSD)

36 Institute of Aquaculture - University of Stirling E.U.S. outbreaks

37 Institute of Aquaculture - University of Stirling  Aphanomyces invaderens

38 Institute of Aquaculture - University of Stirling 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. O 2  Genetic/congenital  Increased susceptibility to infections

39 Institute 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

40 Institute 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

41 Institute 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

42 Institute of Aquaculture - University of Stirling Aquatic animal disease Diagnosis and Investigation Jimmy Turnbull

43 Institute 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

44 Institute of Aquaculture - University of Stirling Standard Growth Curve and Tolerance

45 Institute of Aquaculture - University of Stirling Standard Growth Curve and Tolerance

46 Institute 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

47 Institute 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

48 Institute of Aquaculture - University of Stirling Diagnosis  Very similar to terrestrial animals  Identify and determine cause of problem  Presented information - often misleading  History PATTERN OF THE DISEASE  Species / age / N o affected / Groups affected / Onset / Duration / Clinical signs / Previous diseases / Treatments  General farm information

49 Institute 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

50 Institute 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

51 Institute of Aquaculture - University of Stirling 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

52 Institute of Aquaculture - University of Stirling 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

53 Institute 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

54 Institute of Aquaculture - University of Stirling 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

55 Institute of Aquaculture - University of Stirling 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

56 Institute of Aquaculture - University of Stirling Health Control and Treatment JF Turnbull

57 Institute of Aquaculture - University of Stirling Course of action  Do nothing  May not be acceptable  Change management!!!!!!!!!!!  Kill fish  Loss or emergency harvest  Insurance and welfare  TREATMENT

58 Institute of Aquaculture - University of Stirling Management changes  May be all that is possible  Increase oxygenation  Reduce exposure to carriers  Improve hygiene

59 Institute of Aquaculture - University of Stirling 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

60 Institute of Aquaculture - University of Stirling Cost benefit analyses 2/2 Disease problem DiagnosisSignificance Course of Action 1. Nothing 2. Change management 3. Kill fish 4. Treatment Drug Method Cost benefit analyses ACTION

61 Institute of Aquaculture - University of Stirling Treatment - general precautions  Check fish health  Starve fish  Trial therapy  Check calculations  Mix drug adequately  Beware of stock solutions  Ensure adequate O 2  Dispose of waste carefully

62 Institute of Aquaculture - University of Stirling Treatment  Drug?  Method of treatment?

63 Institute of Aquaculture - University of Stirling Types of treatment  Immersion  Flowing  Flush  Dip  Bath

64 Institute of Aquaculture - University of Stirling Immersion Flowing Flush

65 Institute of Aquaculture - University of Stirling Bath Treatment in cages

66 Institute of Aquaculture - University of Stirling No containment Fish movement Water currents

67 Institute of Aquaculture - University of Stirling Curtain 1/3

68 Institute of Aquaculture - University of Stirling Curtain 2/3

69 Institute of Aquaculture - University of Stirling Curtain 3/3

70 Institute of Aquaculture - University of Stirling Full bag 1/6

71 Institute of Aquaculture - University of Stirling Full bag 2/6

72 Institute of Aquaculture - University of Stirling Full bag 3/6

73 Institute of Aquaculture - University of Stirling Full bag 4/6

74 Institute of Aquaculture - University of Stirling Full bag 5/6

75 Institute of Aquaculture - University of Stirling Full bag 6/6

76 Institute of Aquaculture - University of Stirling Bath treatment  If it goes wrong  Increase aeration  Dilute drug or allow fish to escape from drug  Increase volume  Increase flow

77 Institute of Aquaculture - University of Stirling 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

78 Institute of Aquaculture - University of Stirling Types of treatment  Topical  Injection

79 Institute of Aquaculture - University of Stirling Thank you

80 Institute of Aquaculture - University of Stirling These lectures and other links are on