SAGB2013 Dr Clive Askew - Drummond Lecture


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SAGB2013 Dr Clive Askew - Drummond Lecture

  1. 1. 50 years of modern shellfish farming Where can we go from here? Dr. Clive Askew
  2. 2. Traditional oyster Culture- As of 1960
  3. 3. The Turning Point Whitstable beach 1963 Acknowledgements Canterbury City Museum
  4. 4. Dr. Alan Ansell Acknowledgements; SAMS
  5. 5. Dr. Peter Walne Acknowledgements; Buckland Foundation
  6. 6. Gerald Gardner
  7. 7. Oyster mortality rates Benign bureaucracy
  8. 8. Marcultura hatchery Esteiro-Muros Benign bureaucracy
  9. 9. Marcultura hatchery Esteiro-Muros Benign bureaucracy
  10. 10. Seasalter (Walney) hatchery Benign bureaucracy
  11. 11. Seasalter (Walney) Hatchery Benign bureaucracy
  12. 12. Seasalter (Walney) Hatchery Benign bureaucracy
  13. 13. Seasalter Shellfish (Whitstable) Nursery Benign bureaucracy
  14. 14. Seasalter (Walney)) Nursery Benign bureaucracy
  15. 15. Seasalter (Walney)) Nursery Benign bureaucracy
  16. 16. Seasalter (Walney) oyster farm Benign bureaucracy
  17. 17. Seasalter (Walney) oyster farm
  18. 18. Some lessons from life (Things we have had to learn in SAGB) • TBT • Shellfish toxins •Norovirus and oysters -It ain’t necessarily so-The Party Problem •Conservation, absolute and relative sustainability-The iterative process •Eating shellfish is good for you •We live in a democracy and society makes choices
  19. 19. More lessons from life • Not many people in the UK today understand much about shellfish • The industry is very small and very specialised
  20. 20. Even more lessons from life • We have to live with society’s choices, but we can influence them with sound argument
  21. 21. And a few more • We have to live with ever more complex bureaucracies (benign or Kafka-esque?)
  22. 22. And finally • We should presume they are essentially benign, try to educate them on the value of shellfish and our environmental credentials
  23. 23. Things we are still learning The 3 big ones •Take shellfish seriously-its good for you •MCZs •Norovirus
  24. 24. Seasalter (Walney) oyster farm
  25. 25. MARINE CONSERVATION ZONES (MCZs) • An iterative process ??? Acknowledgements Natural England (Iterare- to repeat)
  26. 26. Norovirus-The Party Problem Oysters v. Humans Were the oysters a risk ? Is it likely that the oysters caused the problem? (In any one instance) We don’t usually know the corresponding human risk NB. WE DO WANT TO KNOW AS BEST WE CAN
  27. 27. The Party Problem The lady holding the party worked in a hospital We can’t hold that against her- we should thank her for concentrating our minds on the problem
  28. 28. The Party Problem The answer to Q1 is Yes The answer to Q2 is we don’t know (irrespective of the norovirus count)
  29. 29. The Party Problem How far does the norovirus count help in answering the question?
  30. 30. The Cruise Liner Problem Ban strawberries or limit the number of passengers?
  31. 31. Has CEFAS (EURL) been asked an impossible question? Out of context-YES (How many people will be on the ship?) There is no ‘right answer’- It is a societal choice which people whose job it is to design the best way to count viruses are not necessarily the best people to ask-but they can help up to a point Bletchley Park statisticians may have been able to give a statistically risk-based answer
  32. 32. Turning it on its head We only know about the passengers, not the food Who should be allowed on? Answer- It depends on the cruise; is it a trip round the bay or Churchill- Roosevelt Summit How serious is the disease? It’s a societal choice
  33. 33. Turning it on its head It’s a societal choice and without guidance the answer is inevitable- Lowest quantifiable level Without guidance, the question prejudices the outcome. The norovirus level just determined how quickly you get there
  34. 34. The Kaplan Criteria are; • Mean illness duration 12-60 hrs •Mean incubation period 24-48 hrs •More than 50% of people with vomiting •No Bacterial agent found NB about 30% of outbreaks do not meet these criteria
  35. 35. Oysters v. Humans Probability in any one case; At random Humans 97 : Oysters 3? Using Kaplan Criteria (24-48hrs) Humans 30: Oysters 70? Using relaxed Kaplan Criteria (12-72 hrs) ?????????????
  36. 36. Oysters v. Humans And in any 2 or 3 case incidents? ?????????????
  37. 37. Oysters v. Humans Probability overall; Is the score ever likely to be Oysters 100 :Humans 0 ?????????????
  38. 38. Has CEFAS (EURL) been asked an impossible question? •They have developed the measuring technique •It is usually applied to give cautionary advice •How much of that can be used in answering the science? •The question now is one of logic, statistics and societal choice about risk
  39. 39. • What are the statistical consequences of relaxing Kaplan’s time criterion from 24-48 hrs to 12-72 hrs for norovirus, given that oysters are usually served in ‘norovirus prone situations’?
  40. 40. Prof. Bill Lands SAGB Conference 2006
  41. 41. New Game ‘Simple Gifts’ Its good to come down where you ought to be
  42. 42. Prof. Bill Lands SAGB Conference 2006
  43. 43. What are the implications of 30%uncertainty? Exclude lowest 30% of single case data? And lowest 10% of 2-case data? And lowest 3% of 3-case data?
  44. 44. We need the help of some Bletchley Park calibre statisticians and logicians, otherwise the oyster industry will pay a heavy price.
  45. 45. Or we need an iterative and risk-based approach starting from the top (most reliable data) down
  46. 46. • Start with the most reliable data (multiple outbreaks) •Have there been multiple outbreaks credibly caused by oysters with low counts of norovirus? •If the ‘outbreaks’ were 3 incidents or less, have statistical methods been used to either exclude unreliable data or deduct probable person-to-person confounding?
  48. 48. Norovirus outbreaks do not stay in one place! One place this year- somewhere else next Can the industry survive that????
  49. 49. What will I do in my (real) retirement?
  50. 50. Prof. Bill Lands SAGB Conference 2006
  51. 51. CHD Mortality and Tissue HUFA y = 3.0323x - 74.8 R 2 = 0.9866 0 50 100 150 200 20 30 40 50 60 70 80 % n-6 HUFA in Total HUFA CHDMortality Greenland Japan Quebec Inuit Quebec Cree USA Quebec Urban HUFA imbalance is a diet-induced dyslipidemia HUFA are long-chain highly unsaturated fatty acids Crete Spain Padova
  52. 52. It may only be an association, but when you find an association as convincing as this- YOU SHOULD PAY ATTENTION Apologies Prof. Bill Lands