Appendix 1
RSPCA welfare standards for farmed Atlantic salmon 52 September 2015
* indicates an amendment
5. Information on major common parasites and diseases
Sea lice
See RSPCA welfare standards - H 4.1 to H 4.7.1
Due to severe welfare problems caused by sea lice infestation, and the possible risk to wild salmonids,
farms must take all reasonable steps to maintain a minimal ovigerous lice population. Farms must develop
an integrated pest management policy based on stocking/fallowing times, strategic treatment regimen and
area management agreements. A sea lice prevention and treatment programme shall be drawn up in
conjunction with the veterinary surgeon; this shall include frequency of monitoring, sampling and monitoring
protocols and threshold lice levels triggering treatments. The programme shall include agreed treatment
regimes, treatment monitoring to ensure fish welfare, critical control and post-treatment monitoring.
Sea lice infestation must be monitored on a weekly basis by sampling a minimum of five fish from a
representative number of pens (depending on the size of the farm). To enable appropriate choice and
timing of treatments, Lepeoptheirus species must be classified into mobile, attached and gravid female
stages; Caligus species are counted but not grouped. A strategic treatment regime must be implemented to
avoid the 'spring settlement' of high numbers of copepodid stages. Treatment regimes and choice of
treatment must at all times consider the welfare of the fish and preference must be given to more 'welfare
friendly' treatments whenever possible, e.g. in-feed treatments are preferred to bath treatments; some bath
treatments may be considered by the veterinary surgeon to be less damaging to fish than other bath
treatments. Consideration must be given to treatment strategies to avoid the potential development of
resistant lice.
* Infectious Pancreatic Necrosis (IPN) virus
IPN can cause serious losses of fish in freshwater and following sea transfer of smolts. Losses can be
as high as 50% with affected fish often showing few presenting symptoms. Outbreaks of clinical IPN
are frequently related to levels of stress to which fish are subjected, particularly at seawater transfer.
Every effort must be made to ensure that stress is minimised and particular attention should be paid to
the following:
adequate and continuing biosecurity and hygiene
avoiding putting infected fish to sea
consideration of stock selection and possible susceptibility to IPN
correct timing of vaccination
size, health, condition and nutritional status of presmolts
use of nutriceuticals, particularly around sea transfer
timing of sea water transfer, judgement of smoltification and the utilisation
of sea water tolerance tests
minimising stress during transport and keeping transport times to a minimum
frequent removal of dead and dying fish
fallowing and area management agreements
controlling other disease conditions such as lice (which can carry IPN virus).
There is no treatment for IPN and control is based upon avoidance and paying attention to the above
factors. The practice of starving the fish at the first sign of the disease is not thought to be an effective
control measure.