Millions in whatever currency you prefer to choose have been thrown at trying to crack the stubborn problem of sea lice in fish farms – so far, with relatively modest success.

This issue is costing the industry dearly, at least £500m each year in Norway and more than £300m in Scotland over the past decade.

According to one leading aquaculture expert, however, part of the solution could be found by taking a simpler approach.

Are Nylund, a fish health professor at the University of Bergen, has been investigating the lice issue for several years and has come to the conclusion that the deeper at sea the fish farms, the healthier the fish.

He has been working closely with the food research institute Nofima, and the technology organisation CtrlAQUA, which is working to make closed containment aquaculture systems more efficient.