Lobster and aquaculture: Studying interactions on Canada's East Coast
On Canada’s east coast, Fisheries and Oceans Canada scientists conduct studies into the impacts that aquaculture may have on lobsters and crabs. Watch to learn how they collect data both in the field and in their labs.
Transcript
Shawn Robinson (researcher)
There's a real interest in the interaction that an aquaculture farm plays in a marine environment. One of the things that it does is give structure to a whole lot of other organisms.
So what was once just plain water that things would drift by, now is almost like an oasis.
Chris McKindsey (researcher)
Most of the studies in the past have been looking at the negative impact on the animals living in the sediments directly underneath and surrounding the farm.
But there's also a potential that there's other more positive impacts of aquaculture because we're essentially putting a bunch of energy, a bunch of food into the system that the animals that live under and around that farm can take advantage of and increase their fitness and their productivity.
With this research, we're looking at two main things.
One is the movement of crabs and lobsters in and around aquaculture sites, and the second is the condition of these animals.
So to follow the crabs and lobsters, what we've done is, we set out a whole big grid of hydrophones and we glued little sound emitters onto the back of crabs and the lobsters.
And then, the hydrophones can follow the movement of the animals on the bottom by triangulation of the noise.
Émilie Simard (biologist)
Using this data, we can find out a lot about the behaviour of lobsters and crabs.
For example, were the individuals present under the culture site?
Did they exhibit foraging behaviour?
Did they exhibit habitat-seeking behaviour?
How large were their home ranges under the culture site?
“869 – they were all gone from there.”
"They moved."
Unknown
"So they're moving around!"
Chris McKindsey
So the way we're doing the second part of this experiment is we're looking at the lipids within the crabs and the lobsters that we're out sampling.
The idea is that the food that's being given to the salmon, that we think that the lobsters and crabs are eating, has a different class of lipids inside of it.
And so, we should be able to follow those lipids, those fats, inside the crabs and the lobsters.
Annick Drouin (researcher)
Lobster and crab samples were collected near the farming site to check the lipid profiles of these individuals as well as in a reference area to compare the numbers with data from an area free of influence from salmon feed.
During dissection of the lobster, I remove the hepatopancreas, which is similar to the liver in that it’s an accumulating organ.
And this is the organ in which we think the omega-3/omega-6 ratio signal will be the most off-balance, making it the best indicator of the vegetable oil signature that we expect to see.
We’re also conducting a lab experiment to confirm how long animals have to be exposed to this feed before we detect a signal.
David Drolet (researcher)
What we’re doing in the lab is basically calibration work.
We have 60 lobsters, all in individual tanks, and for about the past two months now, each lobster has been on a precision-calculated diet ranging from between 0% and 100%.
So at the end of the experiment, we’ll collect samples of hemolymph, which is more or less the lobster equivalent of blood, and we’ll send it off to the lab so they can do a detailed analysis of all fatty acids detected in the hemolymph.
And this helps us to make the connection between the lobster’s lipid profile and the proportion of its diet coming from aquaculture feed.
Once the method is calibrated, we’ll be able to take any lobster out of its natural environment, do the same analysis and compare the result with our lab findings.
Then, by comparing the lipid profiles of lobsters in different regions, we’ll get a better idea of how much an influence aquaculture feed has on bottom-dwelling invertebrates living near aquaculture sites.
Shawn Robinson
And so, this whole interaction is important to understand because there's a lot of interest on the part of the fishermen, for example, that are fishing lobsters in the area, and whether there's any benefits or problems that are occurring because of that, but also to the farmers.
I mean, they want to know what's going on around their farm so they can at least be benign and, possibly they can even enhance some things that we want enhanced.
Chris McKindsey
I like the work that I do because the results from my research are used in the management of aquaculture.
That's to say that we're now looking at aquaculture in a much more holistic point of view than we used to in the past and that's, to some extend, based on the research that I've been doing for the past few years.
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