Fighting off the invasion

Kevin Curley
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FFAW and DFO collaborating to attack green crab

Part 2 in a two-part series

Often called the cockroach of the sea, the green crab is one of the world’s most invasive species, and they’ve given anyone who fishes in Placentia Bay plenty of cause for concern.

Green crab like this one have become a blight on Placentia Bay. Members of the Department of Fisheries and Oceans and the Fish, Food and Allied Workers union are co-ordinating efforts this summer to try and get the population under control.
— Submitted photo

Since they’ve been discovered in 2007, two people have been fighting against the infestation.

Harry Jarvis, project manager for the Fish, Food and Allied Workers (FFAW) union, and Cynthia McKenzie at Department of Fisheries and Ocean Science, have been trying to raise awareness for a number of years on the issue of Green Crab in Placentia Bay.

Some work has been done in years prior with the DFO and DFA. Jarvis says he hoped industrial users in the bay would play a role in their stewardship efforts to handle the problem but so far that hasn’t materialized.

Recently the nickel-processing corporation, Vale Inco, has provided funding to enable trials to see what can be done to control the population.

“As far as the seriousness of the problem, in the whole of North America, Placentia Bay is second only to the state of Maine. In Maine it’s devastated the clam industry and there is a move on by government to take some action,” says Jarvis.

Jarvis says he's hoping DFO and the FFAW and can show a need for a similar focus in Placentia Bay.

Starting in May, Jarvis and McKenzie are going to try and get a handle on the exact extent of the infestation with the help of lobster harvesters. From there, they will implement a plan in the fall where they can hopefully start bringing the population levels down to a controllable level.

They plan to use a Japanese trap proven to be very effective in catching green crab.

“The intent is to start on the fringes and to work our way towards that major infestation up in the North Harbour and Placentia Bay,” says Jarvis.

In Nova Scotia and Prince Edward Island, government has issued nuisance species licences but Jarvis doesn’t think that would work here.

“You can’t suggest we could start harvesting those to sustain a fishery. Unless you are going to remove something that is damaging the environment, you are going to continue to inflict damage on the environment,” says Jarvis, adding “at this point I’m not convinced it would be all that helpful in this area.”

Jarvis says they have had some success by making a focused attempt to remove the crabs.

“We’ve had focused mitigation projects in a couple areas. What we’ve found is that over a period of a week or two weeks, if we make a concentrated effort at removing the things, there is a significant decline in the catch rate and abundance,” says Jarvis.

Jarvis says there is hope as long as action is taken. He says far too much time has been spent talking about the issue.

“Without the help of Vale Inco we would be stuck in limbo like we have for the last five years. Without their contribution, we would be back doing nothing. Nobody else has stepped up to the plate and offered to help,” says Jarvis.

Jarvis says he has more confidence this time around than he did in previous attempts by federal

and provincial fisheries departments.

“We did a couple of projects. But like I said, the other players in the bay, that could have been good stewards and helped out, didn’t. They choose not to help and our mitigation attempts came to a halt. I’m very happy and pleased with the level of commitment Vale Inco has given,” says Jarvis.

Jarvis says Placentia Bay has a serious environment issue on their hands. Lobster landings in the bay are way down compared to 15 years ago and the green crab infestation has made the problem worse.

He says Newfoundland needs to follow Maine’s example, and put emphasis on the need to get the infestation under control and reverse some of the economical damage caused.

“I wish that the regulators in this area were showing some similar urgency to the problem in Placentia Bay. It’s by far the worst infestation anywhere in Canada and Cynthia (McKenzie) documented that the problem is second only to Maine in the whole of North America,” he says.

McKenzie says part of the problem is that people didn’t realize the impact the crab would have. They are a cold-tolerant species and didn’t die out after their first winter as people had thought.

“They don’t die off in the winter. They just burrow down (into the seabed), and the numbers have increased amazingly. If you look at a map from when we first found them in 2007, there was a few hundred up around North Harbour and Come By Chance. We were hard pressed to find more than a couple in Swift Current. Then the next year there were several hundred and the year after that there was thousands,” says McKenzie.

McKenzie says DFO have tried doing population studies by tagging the crab to see how many they get back. They’ve tagged thousands but still can’t get a good estimate.

“We decided to wait to act until we could find someone that would be willing to fund a concerted effort to mitigation. Doing a little bit here and there wasn’t working; it had to be a serious effort. So we’ve got funding for 200 days and we’ve got fish harvesters at each side of Placentia Bay,” says McKenzie.

She says they are going to approach the invasion front area where the crab hasn’t devastated things in the hopes of beating them back.

McKenzie agrees with Jarvis that trapping is the best plan of action. During discussions in 2008, those in the area agreed they didn’t want to use chemicals or bring in another species to eradicate the crab.

“Trapping seems to be the best method, it’s been used in California and they’ve had a lot of success. They’ve had success with trapping in Nova Scotia as well. We feel that trapping is the way to go. We’ve brought in a lot more of these traps and we are going to be working with them,” she says.

McKenzie says her message is to get them early and get them now. She has quite a few experimental licence requests and is providing traps.

“They are going to be seeking out areas before they (green crab) get a foothold and take them out as fast as they can,” she says.

The challenge ahead is daunting, but only time will tell if they can trap enough to keep the populations at bay, or if the aquatic invaders are here to stay.

 

The Packet

Organizations: Allied Workers, Department of Fisheries and Ocean Science

Geographic location: California, Placentia Bay, Maine North America North Harbour Prince Edward Island Newfoundland Canada Cynthia Swift Current Nova Scotia

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