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Risks in farming salmon

Risks in farming salmon. Dan Minchin Marine Organism Investigations Killaloe, Ireland. ERASMUS Course, Coastal Research and Planning Institute, Klaipeda, Lithuania. October 2012. Salmon farming in temperate waters. Collect eggs from fish Fertilize these Rear these in trays

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Risks in farming salmon

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  1. Risks in farming salmon Dan Minchin Marine Organism Investigations Killaloe, Ireland ERASMUS Course, Coastal Research and Planning Institute, Klaipeda, Lithuania. October 2012

  2. Salmon farming in temperate waters • Collect eggs from fish • Fertilize these • Rear these in trays • The hatched fish indoors • Then introduced to freshwater • When smolts introduced to the sea • Harvested after ~18 months

  3. Fish losses can occur due to: • Sea-lice • Diseases • Gelatinous zooplankton • Storm damage • Waste accumulations • Algal events • Predation • Poor management

  4. Sea- liceRelative sizes CAL Caligus elongatus LEP Lepeophtherius salmonis

  5. Lepeophtheirus salmonis =LEP • Compact ectoparasite • In northern hemisphere • On salmon-like fish in the sea • Several generations a year • Two sexes • Normally largest copepod parasite on salmon

  6. Life cycle LEP

  7. Attachment to fish in cages • Fish less active at night, likely infection time • Fish in four cages have similar behaviour • Note: logarithmic scale SUMMER Night

  8. LEP Salmon blood Male Female Eggs = Ovigerous

  9. LEP • Larvae in egg cases resistant to most chemicals • Dark eggs can hatch once detatched from adult

  10. Lice monitoring in Ireland Number of egg bearing lice Number of mobile lice Number of attached lice 30 fish in 3 cages Sample once per month More frequently in spring

  11. Management of egg-bearing LEP in Ireland

  12. Caligus elongatus= CAL • Smaller • Occurs on a wide range of native fish • Generally builds up to problem levels in mid to late summer • Other events may cause high levels of infestation

  13. Normally sea-lice burden of LEP or CAL varies greatly between individual fish • Consequently some fish may be almost free of lice while others have many • Fish nearest surface not feeding or are ‘sick’ tend to have highest burdens

  14. Sea lice burden LEP & CAL • Small number of fish have high burdens • Those with high burdens provide a risk for other fish • Those with high burdens often are not behaving normally, often at surface Irish data

  15. CAL epizootic events • High variability between years • Changing conditions may result in new events Irish data – bottom axis 327 days

  16. CAL epizootic events • Large burdens can appear within a month • Normally take place in summer • Can take place in winter, storm events, harvesting • Sea temperature important 30 days Irish data – bottom axis 104 days

  17. Recently introduced fish to the sea have low lice levels • Older and larger fish have a higher surface area • Low burdens on small fish can be a problem CAL LEP

  18. Broodstock salmon • Surface areas very different for different salmon year classes Salmon smolt

  19. CAL epizootic treatment • Blind small fish have high burdens and usually are small • High burdens of CAL can occur on small ‘runts’ • Some treatments are effective

  20. Sea lice

  21. Sea lice treatments

  22. Other treatments

  23. Cleaner fish • Goldsinny • Rock Cook • Ballan

  24. Fallowing LEP • All indications are that larvae become retained within net cages • Leaving a site idle for 1month or more • But needs to have separated year classes CAL • Not shown to be of advantage

  25. CAL also infest cod-like fish Saithe can have a CAL lice burden and often near cages Cod farming nearby may add to CAL lice burden on salmon

  26. CAL infestation from non-salmon • The farming of cod is likely to result in infestations of CAL • Cod farming close to salmon farming may result in epizootic events cod

  27. Donors within a fish cage • Sick fish (“runts”) and poorly conditioned and diseased fish often swim near to the surface • High parasite loads can be shed to infest other fish in the cage “runt”

  28. During harvesting lice drop off and can infest other fish CAL Salmon blood

  29. Infestation from detatched CAL A likely infestation is from harvesting of fish at other farms Harvesting and drop off of CAL

  30. Normal infestation build-up Infestation from: • ‘Runts’ • Older salmon • Wild fish 3. Saithe may even enter cages during net changes and carry CAL saithe

  31. CAL – Summary of opportunities for sea-lice population growth Harvesting Storm events Salinities Older fish Runts Migratory fish Saithe

  32. Farm losses • High density • Capital costs • Inability to escape impacts

  33. UDN • Occurring on wild fish • Not known on farmed fish

  34. Infectious Salmon anaemia • liver and spleen are swollen and dark (early sign) • pinpoint haemorrhages in internal fat • blood in intestines • haemorrhaging of the liver • pale heart • pale gills • swimming near surface • Might be spread with well boats VIRUS

  35. Pancreas Disease VIRUS • Has beed known as SDS (Suden death syndrome) • Yellow faeces • Motionless fish, unusual behaviors • Not feeding • Regression of pancreas tissue

  36. Furunculosis BACTERIUM • freshwater and marine • produces boils • easily spread • can reside in sediments • widely distributed Aeromonas salmonicida

  37. Bacterial Kidney Disease Renibacterium salmoninarum • creamy white granulomas in kidney and sometimes in liver and spleen • fluid in stomach cavity • haemorrhages on abdominal wall and in the viscera • diffuse white membranous layer on one or more internal organs • enlarged spleen • holes in muscle blocks BACTERIUM

  38. Salmon flesh colour • In the wild from crustaceans • Additives to feed create colour

  39. Kudoa • A protozoan growing in salmon flesh and softening the tissues • Not common problem

  40. Gelatinous zooplankton • Generally affects most offshore sites but problems inshore as well. • Young stages of moon jellyfish • Siphonophores

  41. Storm damage/loss

  42. More exposed areas • Single units • Less problems from accumulations beneath cages • Storm losses

  43. Cage blocks • Sheltered areas • Build-up of fungi from wastes and food pellets • Hydrogen sulphide

  44. Waste accumulations

  45. Fungal accumulations • Mainly in sheltered areas • Wastes can accumulate • Fish feces and uneaten food pellets • Hydrogen sulphide & methane

  46. Algal events • Algal bloom collapses • Icthyotoxins • High densities of algae • Not always evenly distributed

  47. Managing predators • Cormorants • Seals • Humpback whales

  48. SUMMARY • Fallowing sites

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