Prevention Remains Key to Tackling Salmon Lice


Prevention, not treatment, remains key to sea lice problem

March 2, 2016, 7:40 am
Ross Davies    

BERGEN, Norway -- In summing up the “Zero Lice” workshop, the preliminary event to this year’s 11 North Atlantic Seafood Forum (NASF), Kjell Maroni said prevention is still a better alternative than treatment to salmon farmers in their fight against sea lice.

Maroni, who is research and development director at the Norwegian Seafood Research Fund (FHF), said there was “no discussion” that prevention – whether it be technological, physical or biological – remains the number one recourse.

Maroni drew to a close a day that had been distinguished by a number of muscular addresses on everything from the cost impacts of sea lice to the potential of using feed as weapon, and moving operations further offshore.

The general consensus – as has been for some time – is that sea lice remains the enemy number one for the salmon farming sector. And with lice having become more and more resistant to treatment, farmers are left with no choice to but to seek preventative methods.

“Salmon lice are smart,” he said. “They have acclimatized and developed resistance. They will always be there, too, from wild sources, so prevention is better than treatment.”

Early detection should be the first port of call for farmers. This, said Maroni, means a greater focus on sessile lice stages, with checks, ideally, taking place across every cage on a weekly basis.

In terms of biological prevention, vaccines could be “the golden bullet” in the future, he added, but warned delegates that such a solution is still years away.

Instead, farmers could focus on methods already within their grasp, such as large or fast-growing smolts, reared on anti-attachment feed – as recommended by Ewos’ aqua health research lead, Simon Wadsworth earlier in the day – which were described as “key” in Maroni’s roundup.

Technological prevention, including the deployment of semi-closed systems, skirts, underwater lights and submergible cages – were also posited for consideration, as well as the utilization of moving into freshwater fjords.

But, when his presentation moved on to cleaner fish, Maroni sounded a note of caution.

“We think there is still a bit too much hype around cleaner fish,” he said. “Okay, they can be efficient, but it varies. There’s also a biological risk, due to disease. We can reduce their number in the future.”

“They will be used for years to come, but, maybe in ten years, cleaner fish will be an anecdote. Who knows?”

The subject of laser technology for the physical removal of lice also invoked a further caveat.

“They work, but capacity is still an issue,” he said. “There are question marks over production, and tons per hour.”

Similarly, farmers should remember the need to “collect removed lice”, while the focus on fish welfare should always remain high in the mix (“a bit tricky when dealing with the likes of hydrogen peroxide”) – which Maroni, added, has not always been the case in treating sea lice.

“If and when we get new medicines, I urge you to please remember the history,” he said. “I was a farmer in the late 1980s, and I can remember when we developed hydrogen peroxide, when sea lice may have been reduced, but at a cost to fish welfare.”

Echoing the sentiment of fellow speaker Tom Kjode, of the Christian Michelsen Research Centre, Maroni suggested that the salmon farming industry was spoiled for choice by an array of strategies and tools.

However, unlike Kjode, who advocated the use of site and coastal models, on which decisions can be made, Maroni said that current models still carry the danger of being misleading and inaccurate.

“It’s better to avoid sea lice larvae production [altogether] than to rely on inaccurate models,” he countered. “If you can reduce larvae production, models are redundant.”

But it is better to have the quandary of too many tools at one’s disposal than too few – as is the case of industry as it steps up its fight against sea lice.

However, for best management practices to truly click into place and reap the desired effects, players from across the spectrum of aquaculture and science will surely need to put such words of collaboration -- which were in plenty at this event -- into practice, said Maroni.

“I think the tools are probably available, but there is need for large investments, and a need for a total openness and cooperation,” he said, concluding his speech. “It needs to be accepted throughout the industry – also at board and top management level of companies.”