Scottish Sea Farms upgrades Knock hatchery to increase flexibility

Scottish Sea Farms announced that it has upgraded its freshwater hatchery in Knock, on the Isle of Mull, Scotland, to increase its flexibility. The upgrade will improve egg supply and boost smolt capacity by 300,000, enabling the production of 1.5 million smolts per year, thereby complementing production from the RAS (recirculating aquaculture system) hatcheries the company has at Barcaldine and Girlsta, in Shetland.

The company, jointly owned by Norwegian salmon producers SalMar and Lerøy Seafood, announced the improvement in its October newsletter, explaining that the continuous flow-through facility has been equipped with five new 8-meter tanks, replacing several smaller 3-meter outdoor tanks.

According to Scottish Sea Farms, in addition to greater capacity and flexibility in smolt production, this enables a better outcome for the fish, as the new tanks are housed within a large polytunnel with a dark cover that allows for light control, a significant enhancement for fish welfare that also provides weather-protected working conditions.

Much greater flexibility throughout the cycle

As mentioned, Knock has increased its smolt capacity, but Scottish Sea Farms' Head of Freshwater, Rory Conn, explained what other implications the improvement to the freshwater hatchery has beyond this.

"The changes at Knock have been comprehensive and allow us to produce more smolts at the size we want, at the appropriate time for stocking our marine sites, and to do that in a more cost and environmentally efficient way," Conn said.

The company's Head of Freshwater added that in recent years, Scottish Sea Farms has joined the post-smolt trend, more than doubling the average size of smolts, and that its strategy is to introduce larger, more robust animals into the sea, which is equally applicable to Knock and its other hatcheries.

"The development on Mull has also given us much greater flexibility throughout the cycle," he continued. "The plan here had been to move away from egg production and take in fry at around 3-5g from the recirculation hatcheries at Barcaldine or Girlsta where we have greater ability to manage temperature."

"But with egg availability being constrained at certain times of the year,  which pressurises incubation capacity on all sites, maintaining egg incubation and first feeding capacity at Knock is important to ensure we can produce the smolt numbers when they are required," he added.

Rory Conn also pointed out that repurposing tanks, space, and heat recovery infrastructure has been very efficient in terms of capital expenditure, providing production flexibility at a lower operating cost compared to what was previously available at the Knock facility.

First feeding capacity for up to one million fish

The new tanks were supplied by local contractors, and the installation work was supervised by Scottish Sea Farms' Senior Freshwater Engineer, Stephen King, together with regular contractor Archie MacKinnon.

However, Conn credited Knock's veteran manager, Ian Fraser—who Scottish Seafarms noted celebrated 38 years with the company in April—with reimagining the new hatchery configuration to enable a steady supply of smolts.

"The hatching and first feeding stages require more heating and it tends to be less economical to heat water in a flow-through unit than in the RAS at Barcaldine, where water is used multiple times," Ian Fraser explained.

"But when we took the old tanks out, we repositioned eight of them in the back of the shed and, with the new water system, we now have first feeding capacity for up to one million fish," he continued.

"The development, which did not disrupt production at Knock, is now complete and the freshwater team is finding it easier managing the bigger but fewer tanks," Knock's Manager finally pointed out.