New case study: optimising freshwater health Interventions in seawater salmon production (Optibath)

To optimise and validate best practices for the treatment of AGD and sealice using low salinity water

Gill health is a challenge for Scottish aquaculture, directly affecting fish survival and welfare. Traditionally, hydrogen peroxide treatments have been used to manage gill disorders, but these carry risks and limitations. Freshwater or low-salinity baths offer an alternative although barriers, e.g., sourcing water and handling fish, have slowed adoption.

Recent advances in desalination and fish-handling technologies have enabled producers to trial low-salinity interventions. The Optibath project aimed to optimise these treatments by improving water quality monitoring, exploring modified seawater approaches, and assessing welfare impacts. Planned work included testing different salinity levels, treatment durations, and oxygenation methods, alongside real-time water quality monitoring.

Valued at £419k, the project partners were Nevis Marine, University of Stirling, Loch Duart Ltd, and the Norwegian Institute of Marine Research.

The project faced a number of setbacks, e.g., COVID-19 restrictions halted on-site activities and sampling and staff changes further disrupted progress, resulting in the project ending in before its goals could be fully achieved. Despite these challenges, some sampling was completed.

Although the project was curtailed, it highlighted the potential of low-salinity treatments and advanced monitoring tools to improve fish health and welfare. These findings lay the groundwork for future research and innovation in sustainable gill health management, supporting the Scottish Government’s Farmed Fish Health Framework and the sector’s commitment to responsible aquaculture.

The full title of this project is ‘Optimising freshwater health interventions in seawater salmon production (Optibath)’

Read the case study