Difference between revisions of "Sea Lice"

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[[Image:Sea Lice.jpg|right|thumb|200px|Sea Lice - Copyright Joseph G. Kunkel at The Kunkel Fish & Aquatic Invert Site]]
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[[File:Male female sea lice.jpg|thumb|200px|right|Male and female sea lice. Wikimedia Commons]]
 
[[File:Sea lice on salmon.jpg|thumb|200px|right|Sea lice on a salmon. Wikimedia Commons]]
 
[[File:Sea lice on salmon.jpg|thumb|200px|right|Sea lice on a salmon. Wikimedia Commons]]
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*Economic importance to the fish farming industries
 
*Economic importance to the fish farming industries
 
**Especially in North American and in Northern Europe
 
**Especially in North American and in Northern Europe

Revision as of 19:32, 11 July 2011

Caligidae
Kingdom Metazoa
Phylum Arthropoda
Super-class Crustacea
Class Copepoda
Order Siphonostomatoida
Family Caligidae
Species Caligus spp. and Lepeotheirus spp.


Male and female sea lice. Wikimedia Commons
Sea lice on a salmon. Wikimedia Commons
  • Economic importance to the fish farming industries
    • Especially in North American and in Northern Europe
  • Lepeophtheirus is found only in the Northern hemisphere
  • Caligus is found worldwide

Recognition

  • Males measure 6mm in length
  • Females measure 1cm long
    • Have a long egg sac
  • 5 pairs of legs
    • 3 pairs for swimming
    • 2 pairs modified for eating
  • Brown to red in colour
  • Similar in appearance to the horse shoe crab

Life Cycle

  • Eggs released from long egg sacs into environment
  • 2 non-parasitic larval stages
  • 7 parasitic larval stages (nauplius)
    • Copepod, chalimus and pre-adult
  • Life cycle takes 3 weeks to 4 months depending on temperature

Epidemiology

  • Largely found in salt water
  • Most wild salmonids migrate to the sea for part of their life cycle
  • Sealice numbers are low on wild salmonids (adults only)
  • Sealice numbers are high on farmed salmonids (larvae and adults)
    • 90% prevalence
    • Average of 5-10 sealice upon a single fish
    • Most sealice found on dorsal fin, head and back and underside of tail and fins
    • Adults survive for over 3 weeks
    • Migration of larval stages can be up to 1km
    • Larvae locate host by responding to changes in light and vibration

Pathogenesis

  • Adults and larval stages are epidermal browsers
  • Mouth tube of toothed ridges abrades fish epidermis
  • Heavy infections leads to:
    • Epidermal abrasion
    • Haemorrhage
    • Immunosuppression
    • Decreased productivity
    • Death

Control

  • Ectoparasiticides
  • Hidden antigen vaccine
  • Wrasse which feed on sealice
  • Management improvements
    • E.g. All in, all out and 6 week fallowing
  • Stock selection
    • e.g. Selective breeding for resistance

Test Yourself with the Mites Flashcards

Crustacea Flashcards