Humber Arm working to eradicate green crabs from Bay of Islands

Diane
Diane Crocker
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Green crab can be seen in a Fukui trap pulled in the Bay of Islands. ACAP Humber Arm is currently involved in a project aimed at eradicating the invasive species from the bay. Any red crab, or rock crab, caught will be thrown back into the bay.
— Submitted photo

ACAP Humber Arm is involved in a project to eradicate an invasive sea species plaguing the Bay of Islands.

It’ll take some doing.

Executive director Sheldon Peddle knows the bay may never be  free of green crab, but an early intervention could help keep the numbers down enough to lessen the crab’s effects on the bay.

The ACAP-led green crab study is funded by Environment Canada and supported by Fisheries and Oceans Canada, the Newfoundland and Labrador Department of Fisheries and Aquaculture, the Qalipu Mi’kmaq First Nation Band and Grenfell Campus, Memorial University of Newfoundland.

Peddle said the presence of green crab in the province has been documented, with a study of Placentia Bay showing a well-established population.

“We’ve had anecdotal reports of them in the Bay of Islands, but never really formally documented to this extent.”

Last year, ACAP conducted an eelgrass study in the bay to learn more about the presence, distribution and abundance of the saltwater perennial flowering plant that resembles blades of grass.

Green crab like to live in eelgrass beds, so Peddle said moving from the eelgrass study to one on green crab was a “natural evolution.”

“They come in. They are very aggressive. They will force other species out of the habitat. They will also destroy the habitat,” said Peddle.

“It is very important that we eradicate as many of them as we can to protect the environment and to protect the native species.”

In some cases, he added, it may be commercial species that are being pushed out so there could be potential financial consequences if the green crab are not removed.

Peddle said ACAP has been using a two-pronged approach in conducting the study.

The first phase will identifiy the presence and distribution of the crab by going out and sampling the bay.

Peddle said the first attack considered was to focus efforts on the outer Bay of Islands. This is where finding green crab would be most likely since they work their way into the bay and because the area has a well-suited habitat.

However, he said it was later decided to cover the entire Bay of Islands, including Humber Arm, Middle Arm and North Arm, focusing on areas where ACAP knew there was eelgrass.

About 20 locations were hit. Peddle didn’t have exact numbers but said they are high. He noted a significant number of green crab have been found in the Inner Bay of Islands. Last Friday, 500 green crabs were removed from traps set the day before in the area of the breakwater around the Bay of Islands Yacht Club

“It’s a little bit surprising and alarming that they’re in this far,” said Peddle.

He said the large numbers in the Inner Bay of Islands indicate the presence of green crab in the bay is more established than previously assumed.

“They have been here for a number of years,” he said, adding that large adults, juveniles and berried females — females with egg sacks — have been found at the inner bay locations.

“The presence of juveniles would establish that there’s been breeding populations here for a number of years.”

With most of the sampling completed, ACAP‚ has now moved into the second phase of the project where the objective is to eradicate the crabs from the bay.

“Because these are an invasive species, the only way we were able to get a permit from DFO to actually do the trapping was that it had to be destructive sampling,” said Peddle. “Once we catch the green crab ... we do have to ensure that they’re destroyed.”

When the crabs are removed from the traps they are placed in bags which are labelled based on location, then frozen for 48 hours. The freeze not only kills the crabs, but also any eggs. After that, the scientific work of measuring them and identifying the numbers of males and females takes place.

Once that’s completed the green crabs are destroyed. Peddle said normally all that is required is that they be sent to a landfill, but in this case ACAP is looking at sending them to a composting facility in Stephenville.

Peddle said the eradication for 2013 will continue for as long as weather conditions allow. He said he’s is hopeful funding will be made available on an annual basis.

Organizations: Environment Canada, Fisheries and Oceans Canada, Newfoundland and Labrador Department of First Nation Band and Grenfell Campus Memorial University of Newfoundland.Peddle Islands Yacht Club

Geographic location: Bay of Islands, Bay of Islands.It, Placentia Bay Inner Bay Middle Arm North Arm

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