MARINE Harvest has confirmed that the outbreak of a bacterial infection at one of its Lewis farms has resulted in the loss of 500 tonnes of fish.
Some 125,000 salmon of around 4kg each have died so far, with regular lorry loads carrying the carcasses from the island.
Steve Bracken, the company’s business support manager, said: ‘The health issues we have had at Loch Erisort since the end of August are the result of a bacterial infection called Pasteurella skyensis which only affects fish and is completely harmless to humans.
‘Strains of the Pasteurella bacteria are present in many species of fish and outbreaks of infection occur from time to time.
‘In the salmon farming industry we are experiencing ongoing changes in the sea conditions, due to factors such as climate change and global warming, which mean we have to monitor our fish even more carefully and be ready to respond accordingly.
‘The salmon are responding well to treatment from our team of vets and we hope that we are close to resolving the problem.
‘So far, 500 tonnes or approximately 125,000 fish have died. The dead fish are handled by a specialist waste management company who take them away by lorry to the mainland where they are treated by anaerobic digestion.
‘The biogas produced is sold to the National Grid and the end product is used for fertiliser.’
He said the fish are being treated with antibiotics, which now seem to be working, and the farm is ‘through the worst of it’.
Strict biosecurity measures have prevented the infection from spreading to a neighbouring farm, said Bracken.
The devastating infection comes at a time when Marine Harvest has achieved better control of other health challenges, such as sea lice and AGD, which have cost the whole industry millions to treat.
‘This year we got off to a very, very good start; we’ve still got AGD and lice present, albeit at a much lower level, but it’s clear that when your fish are challenged with these two things and then they are exposed to a third challenge, that takes its toll,’ Bracken said earlier this month.
‘We’ve been here before and we know what can happen, but we also know what we can do to prevent the spread of it.’
Production volumes in Scotland overall dropped to 162,000 tonnes in 2016 but are expected to be back to previous levels of more than 170,000, tonnes this year after success with an array of treatments.
Picture: Marine Harvest’s Steve Bracken