Cleaner Fish: A new tool to mitigate sea lice

Clayton Hunt
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The connor to the rescue

A cunner being measured at the Ocean Sciences Centre in Logy Bay.

Submitted photo

They say that every creature on the planet has a purpose, that every animal has a reason to be here.

And now, it seems possible that the once lowly connor or cunner that hangs out at any wharf in Newfoundland and Labrador, may play a prominent role in the province’s aquaculture industry. It appears that cunners may be used to help control sea lice on cultured salmon.

Danny Boyce is the Facility and Business Manager of the Dr. Joe Brown Research Aquatic Building which is part of Memorial University’ Ocean Sciences Centre in Logy Bay.

Boyce said that lice infestations are one of the biggest challenges in salmon aquaculture and it can cost the producers up to $300 a tonne produced each year in losses and treatments.

Aquaculture companies around the world are seeking alternative methods to control sea lice as lice may build up a resistance to the therapeutants used to control them and these treatments may have possible effects on non-target organisms.

Wrasses, called connors or cunners in Canada, are being used in commercial production cycles in Norway and Scotland as part of an integrated pest management approach and to avoid dependence on chemical lice treatments.

Boyce and his colleagues – John Evely, Denise Tucker and Jennifer Monk -  – are involved in a project to raise cunners in Newfoundland that may be used to help alleviate sea lice issues in provincial aquaculture projects.

Boyce said, “Up to this point some 30 million cunners have been taken from the wild in Norway for this purpose. When you remove that number of any species from the wild it may have some profound effect on the ecosystem.

“We are completing a project where we are raising cunners from the eggs using local stocks. We’re looking at this from the culture end but it remains to be seen if this is a project and investment that the aquaculture companies will be willing to invest in.

“Wrasses or cunners are already being used in salmon aquaculture in Europe and Cooke Aquaculture is testing this idea in some of its projects in New Brunswick.

“The cunner has received attention as the best candidate to serve as a Cleaner Fish for the Canadian Atlantic salmon industry.

However, little is know about its ability in cleaning lice from salmon or its adaptivity to captive culture conditions.”

Boyce said that the MUN project is in the very early stages and it takes while to grow a cunner, as the eggs are only about .8 mm in size to start with. It also takes a while to understand the biology and culture conditions that come with a new species.

“It may be a slow process but sea lice are probably going to be with the industry for a long time especially with our warming water temperatures.

“What we’re looking at basically is a possible alternative measure to treat sea lice that could be really beneficial to the salmonid industry. These cunners could be user friendly and this may be something the general public would look at and say that this is an alternative to the other treatments being used today.”

Geographic location: Newfoundland and Labrador, Norway, Logy Bay Canada Scotland Europe New Brunswick

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