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Aquaculture research: Alternative control methods for managing sea lice

In Canada's aquaculture sector, Fisheries and Oceans Canada is particularly concerned with helping this industry develop in a sustainable and responsible way.


Narrator: In Canada's aquaculture sector, Fisheries and Oceans Canada, or DFO, is particularly concerned with helping this industry develop in a sustainable and responsible way.

DFO's focus is based on sound science: the importance of research that informs regulatory decision making, ensures healthy aquatic animals, and explores new technologies and innovative techniques to improve aquaculture practices...including the development of better preventative tools.

One specific challenge being faced by fish farmers today is sea lice...
Sea lice are a natural marine parasite that have been attaching themselves to fish populations for millions of years and continue to affect both farmed and wild fish, worldwide.

Although not a risk to human health, sea lice have become a troublesome problem in aquaculture, particularly for salmon farmers.
They tend to multiply quickly at aquaculture sites in some regions of the country, and in large enough numbers could pose health risks to the farmed salmon. So far, different methods have been used to address the issue with mixed results.
Fortunately, science offers great promise to help control sea lice at fish farms. Already, we are seeing important progress as researchers look for newer and 'greener' control methods.

DFO scientists, Dr. Shawn Robinson at St. Andrews Biological Station, on the Bay of Fundy...and Dr. Chris Pearce at the Pacific Biological Station in Nanaimo, BC...are working with partners in industry and academia to find alternate solutions for dealing with sea lice.

Dr. Shawn Robinson: "...Our research on sea lice right now is, is sort of targeted at coming up with alternative treatments than the status quo, right now.
The reason for that research is twofold. One is to try and better understand the life history of sea lice, so that we can intervene and kind of break that cycle. Second of all, we are trying to find additional tools that the industry can use.”

Narrator: One set of "alternative tools" Dr. Robinson is working are "attractants", sensory and behavioural cues that sea lice larvae and juveniles use to find a fish to latch on to:

Dr. Robinson: "... We've found that the larvae and even the adults to a certain extent are attracted to light. It could be white light, but we find that they are particularly attracted to blues.

We also find that they're also attracted to pheromones. So pheromones are sort of sex attractant chemicals that animals use for communication. And so, for sea lice, some of those attractants are probably salmon smell or whatever is, you know, sexy at the time to a sea louse.
In nature, it helps them find a mate. In the industrial world, hopefully it helps them find a trap.”

Narrator: Though the traps seem to work well, there is still a challenge facing the scientists and their industry partners:

Dr. Robinson: "And the problem is that sea lice aren't the only things out there. And they're of relatively low abundances in comparison with the others...and so we're gonna have to refine that, to create a more specific attractant that will just draw the sea lice in”

Narrator: There is another, perhaps more promising angle that DFO and their partners in industry and academia are exploring:

Dr. Chris Pearce: “And one of the ideas that we came up with a number of years ago, and it fact, it was Dr. Shawn Robinson's original idea ...we thought maybe we could use filter feeding shellfish around salmon farms as a natural vacuum cleaner, to suck up planktonic sea lice larvae and reduce lice populations on the farmed fish.

Up until now, we've been primarily focussed on doing lab trials, looking to see if these species of filter feeding shellfish can indeed consume sea lice larvae.
And the research on both coasts has been very positive. It's shown that all species that we've tested, can indeed consume planktonic sea lice larvae.”

Dr. Robinson: "I am very pleased with the results we have so far. We found in the lab, that if we take sea lice into the lab...the egg bearing females, we can produce lots of larvae, we can put those larvae in the tanks with filter feeding shell fish such as the blue mussel. We can put it in with the sea scallop. And they will eat lots and lots of larvae. They will filter them out of the water chunk, chomp them right up and they digest them so the larvae are gone.”

Dr. Pearce: "That's great. But, where do you go from there? Because, in the natural environment, out on the field, you have a lot of different things to deal with. Water currents, turbulence, waves, the fish. So, the next thing to do after the lab experiments is to follow up with field trials which is what we're actually doing right now.

So we have commercial scale quantities of filter feeding shellfish set up at a commercial salmon farm around certain pens and over time we're going to be monitoring planktonic sea lice levels, sea lice larvae levels, as well as adult lice on the fish in both experimental cages that have the shellfish around them and compare those numbers with numbers in control pens, without shellfish, to see if there is any difference in either the planktonic lice larval levels or the adult lice levels on the fish.”

Narrator: These two areas of research - traps and filter feeders - are aimed at sea lice in their early growth stages; DFO and its partners are also starting work on other ways to reduce sea lice who've made it through to the adult stage.

Dr. Robinson: “On that strategy, we are using sort of predators of those and those would be things like the cleaner fish...and a lot of those fish are like wrasse, in the wrasse family. And we are using similar fish here. So the Cunner, that we... that's local. And that will pick off some of the adult lice. Particularly the large egg-bearing females.

And there's another fish as well, called the Lumpfish. And it's, it's a small cute little fish, kind of looks like Nemo a bit maybe, but it sticks on the side of the salmon, and can actually pick off the lice”

Narrator: The question may be asked: is the challenging relationship between sea lice and aquaculture close to being finally resolved?

Dr. Pearce: "I'm thinking it's going to be a constant battle. This is a natural species that's out there in the wild. It's always going to be there. It's always going to be an issue for the salmon farmers that they have to deal with. They will probably end up having a variety of potential fixes in their toolbox to address sea lice issues.”

Narrator: And so, along with its partners in academia and the aquaculture industry, DFO and its scientists continue their research to find innovative ways to help manage these types of issues using an integrated approach... this investment in essential research will ultimately facilitate improved fish health practices for a growing industry.

Special thanks to:

Natural Sciences and Engineering Research Council of Canada (NSERC)

The Canadian Integrated Multi-Trophic Aquaculture Network (CIMTAN) and
its Scientific Director Dr. Thierry Chopin, Professor, University of New Brunswick, as well as the
scientists and graduate students who have contributed to this important research under CIMTAN

University of New Brunswick, University of Victoria, and Vancouver Island University

Cooke Aquaculture Inc., Grieg Seafood BC Ltd., Marine Harvest Canada Ltd.

The Huntsman Marine Science Centre

Fisheries and Oceans Canada’s Aquaculture Collaborative Research
and Development Program (ACRDP)

Fisheries and Oceans Canada Scientists: Dr. Chris Pearce and Dr. Shawn Robinson

Fisheries and Oceans Canada’s Pacific Biological Station and the St. Andrews Biological Station

Video Production Team
Production and Direction: Stonehaven Productions, Michael Taylor and Scott Mason
Project Management (DFO): Tara Donaghy and Emily Nelson

Special thanks to Ryan Leblanc (St. Andrews, New Brunswick) for generously providing the music


© Her Majesty the Queen in Right of Canada, 2013

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