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Grieg expanding use of semi-closed salmon farm system off Island’s West Coast

Made-in-BC technology resulted in lower sea lice levels in trial, company says
A diagram of the semi-closed containment system Grieg Seafood BC Ltd. has trialed, showing tarp barriers extended. Figure courtesy Grieg.

After trialling a new made-in-B.C. semi-closed system at its salmon farms on the Sunshine Coast, Grieg Seafood BC Ltd. will be expanding the use of this technology to its farms in Esperanza Inlet on the west coast of Vancouver Island.

This system, called ‘CO2L Flow’ (pronounced ‘cool flow’) is a type of semi-closed containment, allowing salmon farmers to raise or lower custom-designed farm enclosures. This ensures farmed salmon can benefit from natural ocean conditions, while providing protection to wild salmon, according to a Grieg news release.

The barriers can be lifted outside of wild salmon migration periods, allowing the farmed fish to benefit from natural ocean conditions, temperatures, currents, and oxygen levels, the release says.

Grieg Seafood BC Ltd. tested the system at its farm off the Sunshine Coast. During this trial, farmers noted better growth, lower mortality, better feed conversion rates (meaning feed is more efficiently converted to growth), and a reduction in the need for sea lice treatments, according to Grieg.

“As a company, we are always looking for ways to improve our operations, and this includes transitioning from standard farming equipment, to new, cutting-edge technology aimed at reducing potential impacts from our operations,” Rocky Boschman, managing director, Grieg Seafood BC Ltd, said in the news release.

“This has several benefits, including preventing the lateral interaction of wild and farmed salmon populations, providing protection for farmed populations from harmful algae, and allowing our farmers to better control water quality in the system using a unique aeration technology.”

The amount the system reduced sea lice levels during the trials was such that the fish did not require treatment for lice, said Boschman.

During wild salmon migration periods or when there is algae, the system’s barriers can be lowered, forming a barrier between wild salmon and the farmed population, said ​​Dean Trethewey, Grieg seawater production, certifications and regulatory director, in the release.

“This prevents lateral interaction, and significantly reduces the transmission of sea lice between the populations,” said Trethewey.

When barriers are lowered, the system features technology that works to increase oxygen levels.

“The barriers can be fully lifted outside of these periods, allowing the farmed fish to benefit from natural ocean conditions, temperatures, currents, and oxygen levels,” he said.

The company announced on Feb. 8 that it will install the semi-closed system at all three of its farms in Esperanza Inlet, located off the west coast of Vancouver Island, in time for the out-migration of juvenile wild salmon in early 2023. On Jan. 14, representatives from Grieg Seafood BC Ltd., CPI Equipment, Poseidon Ocean Systems, Oxzo Technologies Canada, and Fidelis Aquauculture joined virtually to mark the signing of construction contracts for the new system.

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