Aquaculture

1. Aquaculture Royal Veterinary College January 2004 Jimmy Turnbull

2. Outline of the morning • Aquaculture • Introduction to aquatic animal health • Aquatic animal disease diagnosis and investigation • Disease control and treatment

3. 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. 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. FAO 1995 • Aquaculture = 23% of total aquatic prod.

6. 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. FAO 1995

8. 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. Size and value of aquaculture • UK Atlantic salmon industry • 120,000 tonnes/year • £300 million 1999 • World production 472,000 tonnes/year

10. Example - Salmon life cylce Sea Fresh water

11. 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

13. 1st USA 2nd Japan 3rd Germany 4th UK

14. 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

15. Role of vets in aquaculture • Diagnosticians • Health management / management • Research • Training / teaching • Government animal health control • Development

16. Introduction to Aquatic Animal Health JF Turnbull

17. Why Study Aquatic disease?

18. 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. 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. 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. 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. Host/Environment/Pathogen Over used and abused

23. Environment • What can cause stress = anything!!!! • For example : • Environment or management • Nutrition • Behaviour • Other diseases • Treatments

24. Host • Very wide range of species • Salmon and carp more different than dog and cow

25. 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. Fish Skin

27. Host • Fish - Non-specific immunity • Humoral - compounds in body fluids • Circulating cells • Tissue-dwelling cells

28. Host • Fish - Specific immunity • Humoral - compounds in body fluids • Circulating cells • Lymphocytes - Antibody production • Phagocytes - Phagocytosis and APC

29. 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. 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. Pathogens • Same range of infectious pathogens as in mammals • viruses • bacteria • fungi • protozoa • metazoa

32. 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. Pathogen

34. Pathogens • Examples • WSD • EUS • Ich • Salmon lice

35. White Spot Disease (WSD) • Cause WSSV and other factors • Massive impact US$600 million in Thailand in 1997 • Affects all systems Extensive to Intensive

36. 1972 1988 1983 1972 E.U.S. outbreaks 1998

37. Aphanomyces invaderens

38. 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

39. 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. 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. 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. Aquatic animal disease Diagnosis and Investigation Jimmy Turnbull

43. 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. Standard Growth Curve and Tolerance

45. Standard Growth Curve and Tolerance

46. 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. 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. 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

49. 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. Patterns of disease • Sudden acute sever mortality - CAUSES? • Infectious problems - PATTERN? • Propagating • Point-source • Nutritional problems - PATTERN? • Associations with risk factors