Loch Duart develops sea lice filter

Scottish salmon farmer Loch Duart Ltd. is developing an innovative way of collecting and removing sea lice during the handling and sorting process.

“Sea lice have been around as long as salmon have existed,” said Nick Joy, the company’s managing director. “Loch Duart hopes and aims to work to ensure that salmon have a long future ahead and that sea lice will not be a significant factor affecting the species’ future. While we are not yet at the point where we can say that sea lice are over as an issue, we can say that we have taken a new step in the control of this perennial pest.”

Many times during their life cycle, salmon are sorted by size to reduce bullying, to separate maturing salmon and to be harvested. When the salmon are pumped from the net, sea lice are often dislodged as they enter the high pressure flow, according to Loch Duart.

Over the past year, Loch Duart has developed a filter system that removes the eggs from the sea lice and traps them so that they can be removed and destroyed. The system had to cope with big flows of water and microscopic sea lice while maintaining the flow of fish. The speed of handling and the quick return of salmon to the water are critical to their welfare.

After trialing a prototype filter successfully, Loch Duart is installing additional units to allow filtration of harvests and grading at the same time. The company’s engineering team is also working to refine and integrate the pump and filter for more efficient energy use.

“We know from previous use that our pumps cause about 70 percent of sea lice to detach. Thus if we could catch all of these, both the numbers and the potential future numbers of sea lice would be considerably reduced without recourse to medicines,” said development team leader Sonja Brown.

Loch Duart produces about 5,600 metric tons of salmon annually.


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