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AQUA 2012: Minimising Pain of Eyestalk Ablation in Freshwater Prawn

Crustaceans Health Welfare +3 more

CZECH REPUBLIC - Carlos Sainz-HernJuan from the Centro Interdisciplinario de Investigacipara el Desarrollo Integral Regional (CIIDIR IPN -SINALOA), Mexico, has examined the most pain free way to remove the eyestalk from freshwater prawn, writes Lucy Towers, TheFishSite Editor, at AQUA 2012, Prague, Czech Republic.

Lucy Towers thumbnail

Mr Sainz-HernJuan noted how eyestalk removal is neccessary in order to study the hormone/reproduction of prawn.

To propose a better and less painful procedure to eliminate the flow of hormones from the X Organ Sinus Gland in adult prawn, Mr Sainz-HernJuan looked at prawn response to four different procedures in his study.

Procedure one was ligation of the bottom of the eyestalk to stop hormone flow. The second method involved cutting at the base and then squeezing, the third involved cutting at the base and squeezing but was followed by covering of the bleeding area and technique four only manipulated the eyestalk.

Mr Sainz-HernJuan decided that pain in the prawn could be defined by:

  • tail flicking
  • rubbing wounded area
  • disorientation
  • sheltering
  • recoil
  • stooping

Of the three procedures, ligation presented all the affects listed above with the use of Xylocaine not helping to minimise pain. Ligation caused 50 per cent more flicking, 90 per cent more rubbing, disorientation and up to 80 per cent more recoil than the other techniques.

The technique that seemed to cause the least discomfort was the treatment in females which used an anaesthetic and covered the ablated eyestalk. This presented only 20 per cent more flicking and rubbing and only 30 per cent were not sheltered. The prawns also did not show disorientation, recoil or stooping

In conclusion, Mr Sainz-HernJuan stated that eyestalk ablation is traumatic in both males and females. The use of Xylocaine as an anaesthetic helped to alleviate some of the affects seen, but not all. Mr Sainz-HernJuan did not recommend ligation as a method as this was seen to cause the most pain