RAS hatchery cuts two months off fish time at sea
Scottish Sea Farms is celebrating the harvest and sale of the first smolts from its new recirculating aquaculture system (RAS) hatchery at Barcaldine, near Oban.
The smolts, which were grown to harvest size at SSF’s Loch Nevis C farm, has an average weight of 178 grams when put to sea - more than double the weight of SSF’s previous smolts – and required two months fewer in the sea to reach market size.
“Thanks to its state-of-the-art RAS we now have much greater control over the key growth factors of water quality, oxygen levels, temperature, light and speed of flow,” said SSF freshwater manager Pål Tangvik in a press release.
Peak health
“This creates a more stable environment compared to conventional flow-through hatcheries which, due to the fact they draw in freshwater from rivers or lochs, can be subject to changes in weather.
“We’re also able to keep each generation of fish completely separate and bio-secure, meaning we can maintain peak health throughout the freshwater cycle.
“We’re seeing is bigger, healthier smolts which not only require less time at sea but are better able to withstand the natural challenges of the marine environment.”
Energy re-use
SSF’s 17,500m² hatchery can produce up to 10 million smolts annually for the company’s 42 marine sites around Scotland’s west coast, Orkney and Shetland.
Up to 99% of the 5,200m³ of fresh water used daily is recirculated, and is cleaned every 30 minutes via a complex system of filters and UV light. The water is maintained at a constant temperature using a combination of heat pumps and heat exchangers. These use less energy than traditional kerosene boilers or electric chillers and can also recover heat from wastewater for re-use.
A biomass system run on locally sourced wood chip provides heating and hot water throughout the rest of the facility.
Agricultural fertiliser
SSF managing director Jim Gallagher said: “When it came to transforming our freshwater farming, it seemed only natural that we do so in the greenest way possible: from reducing our use of fossil fuels or finite resources such as fresh water, to provision for our own hydro scheme.
“Through the technologies available to us, we’re also able to capture any waste material from the growing cycle. This is then removed by Invergordon-based waste management company, Rock Highland, who recirculate it as nutrient-rich agricultural fertiliser.
“It’s all part of our commitment to responsible, sustainable food production.”
