Photo: Scottish Sea Farms

Holistic Health and Welfare Strategy Drives Increased Survival Rates at Scottish Sea Farms

Scottish Sea Farms achieved a significant improvement in fish health last year, demonstrated by a 41% reduction in mortality compared to the previous year. This improvement followed increased investment in mitigation strategies and a focus on preventative measures.

Survival rates returned to historically high levels, reaching 90% from 82% in 2023, as favorable biological conditions and improved gill health replaced the warmer seawater temperatures that had previously posed sector-wide challenges. Harvesting volumes also increased substantially, reaching 40,400 gutted weight tonnes (gwt) from 24,900 gwt in 2023, with higher harvest weights. "We're back to where we should be, but we remain vigilant," stated Ralph Bickerdike, Head of Fish Health and Welfare. "We've learned from the challenges of 2022-23 and reviewed all operations, aiming for even higher survival rates."

A key factor in this improved performance is the company's breeding program, developed in collaboration with AquaGen Scotland. This program has produced broodstock from Scottish Sea Farms salmon selected for their robustness in the Scottish environment. "The first crops from these fish, harvested in 2024, performed exceptionally well," Bickerdike noted. "We are continually selecting fish from our farms for broodstock, anticipating further improvements in climate resilience through successive generations."

Feeding strategies were also refined to meet the seasonal nutritional requirements for fish health and welfare. "We collaborated with our feed supplier to adjust feed composition in Q3, when fish health is most vulnerable, yielding promising early results," Bickerdike explained. Temporary feed withdrawal during challenging periods, such as jellyfish and plankton blooms, further contributed to survival and enhanced fish welfare by keeping fish away from surface hazards.

Technological advancements in the supply chain have also aided fish health across Scottish Sea Farms' operations, enabling earlier disease detection and rapid intervention. "We've been evaluating advanced underwater biomass cameras, which monitor individual fish for weight estimation and condition assessment without handling," Bickerdike added. "These provide real-time welfare data, allowing for timely action." Modern diagnostics, such as PCR swabs for amoebic gill disease (AGD), and daily water sampling have improved treatment decisions and environmental monitoring.

New biosecurity protocols, pioneered in Shetland, have minimized disease introduction through an air table-based app for vessel and equipment inspections. The acquisition of two wellboats equipped with reverse osmosis for freshwater treatments and FLS delousing systems has enabled simultaneous AGD and sea lice treatments, reducing fish handling and improving welfare.

Mainland Regional Production Manager Innes Weir attributed the improved results to a combination of increased resources, lower lice levels, reduced jellyfish presence, and cooler water temperatures. "We have gained a deeper understanding of effective practices," Weir stated. "We relocated some farms to more suitable locations with improved water exchange and wellboat access. We also upgraded farms with fewer but larger pens, with all mainland Scotland farms transitioning to larger pens by April, enhancing hydrological dynamics and promoting growth."

Revised training programs for enhanced fish husbandry have complemented the new farm layouts, with Weir acknowledging the instrumental role of the farm teams in achieving these results.

Scottish Sea Farms is continuing to enhance secondary predator netting, evaluate cleaner fish deployment, upgrade freshwater facilities, and collaborate on R&D projects to further improve fish health and welfare. Notably, the company achieved improved survival without antibiotic use in production farms. "We have improved best practice sharing across our farms, with regular reviews of fish welfare and biological performance," Bickerdike concluded. "This allows us to anticipate and address challenges more effectively."

editorial@seafood.media
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Address:	Laurel House, Laurelhill Business Park, Polmaise Road
City:	Stirling
State/ZIP:	Stirlingshire (FK7 9JQ )
Country:	United Kingdom
Phone:	+44 1786 445 541
Fax:	+44 1786 450 164
E-Mail:	sales@scottishseafarms.com
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