Farms see drop in salmon disease and sea lice
Scotland’s two leading salmon farmers have reported a sustained improvement in fish health during the first five months of 2018, with a marked reduction in disease-related mortalities.
Figures for Marine Harvest Scotland and Scottish Sea Farms show the number of fish that died as a result of disease fell by more than half between January and May compared with the previous six months.
Disease-related mortality is also lower year on year, with the two sea farmers reporting a reduction of 61 per cent and 27 per cent respectively compared with the first six months of 2017.
The sustained improvement follows a challenging year for some farms owing to warmer than average sea surface temperatures. These warmer temperatures can encourage marine organisms to thrive where ordinarily they might not occur in abundance, posing threats to fish health in the form of harmful algal or jellyfish blooms, as experienced in 2017. In response, both producers have invested in new technologies, including equipment to monitor salinity and oxygen concentration in real-time, helping farmers make swift and informed decisions, innovative new netting helping to eliminate gill disease and underwater cameras to observe salmon within the pens and respond quickly to any changes in innate behaviour.
Both producers are also investing in multi-million pound state-of-the-art hatcheries which will enable young salmon to be grown to a larger, more robust size, thereby shortening their time at sea and lessening the chance of infection from other marine creatures. Meanwhile, adding to the improvement in overall fish health, both companies have reported significantly lower lice levels from January to May 2018. In the case of Marine Harvest Scotland, sea lice levels were 49 per cent lower compared with the previous six months, while Scottish Sea Farms were 34 per cent lower.
Ralph Bickerdike, head of fish health at Scottish Sea Farms, said: ‘Colder temperatures over winter 2017 have some part to play. However, we’re also seeing the cumulative impact of investment in integrated sea lice management, including sea lice shields which reduce the number of lice entering salmon pens, use of cleaner fish which eat sea lice and hydro and thermolicer technology which washes off and collects sea lice.
‘The result is we’re seeing some of our healthiest, strongest fish yet.’
Across the sector, the Scottish Salmon Producers’ Organisation says figures show sea lice levels are at their lowest since July 2013.