Calamity crab: Foreign crab species threatens Placentia Bay ecosystem

By Gavin Simms

FOR THE SOU’WESTER

William Hepditch and Charles Brinston have been laying crab pots in the shallows of North Harbour for the past five weeks. From their little wooden dory they haul in the morning and again in the afternoon, loading the boat to their knees each time.

It's too bad the crabs are going straight to the dump.

They're not fishing for food, they're fishing for the future of their livelihood, removing the ruinous European green crab from the waters of North Harbour, Placentia Bay, N.L. where not all green is good.

They were hired by the Fish, Food and Allied Workers Union to remove as many crabs as possible from the sea, and to get a better grasp on the number of crabs out there.

They may have hauled their last catch. But both fishermen know they've just scratched the surface of this deep trouble.

"They better put someone at it. They better get more than one boat too, if they want to try and make a dent in it," Hepditch says.

"My buddy took an old frozen rabbit out of the fridge and put it into a crab pot. Next morning he hauled it up and it was full, nothing left of the rabbit, only bones. Anything at all, any meat whatsoever, they'll eat."

In five weeks they took approximately 500,000 crabs out of the water Hepditch says. Five hundred pounds has been the usual daily catch, with 29 pots.

Tied to the North Harbour wharf, they scoop the little green creatures into white plastic bags, and it's good riddance.

The crabs have more life in them than the average crustacean native to this island. They scurry and clap and shoot like spiders in the boat's hold. Their agility is just the problem. They can easily out-compete all other crabs around. No other crustaceans can co-exist with them once they move in and take over; nothing else stands a chance. Mussels, oysters, scallops, and even lobster stand to be consumed.

Apart from what they eat, there is also the concern for where they eat. The green crab burrows deep into the ground seeking out clams, and as a result destroys fish habitats on the ocean floor such as eelgrass beds and kelp.

Unlike in its native habitat, the green crab has no natural predator here in its newfound home. Its eating patterns leave a path of devastation, with little to no survivors remaining after an infestation takes hold.

Females are capable of spawning up to 185,000 eggs per year. The green crab can rotate its claws over its back, enabling defense from predators attacking from behind. It can live out of water for up to a week, in the sun. It can easily survive in fresh water.

Swift Current Academy science students from grades 7 to 11 took part in a beach combing effort in North Harbour, N.L. on Sept 29. Representatives from the FFAW and the Department of Fisheries and Oceans were lending a hand. One by one, green crabs were picked off the shore, from beneath the kelp and rocks.

Although samples of the crab and other data were collected for study purposes, the main reason for being there was to remove as many crab as possible from the site, and to gain the province's attention.

DFO research scientist, Dr. Cynthia MacKenzie, was on hand at the beach. She brought graduate students with her, field technicians and divers. She knows her enemy quite well and wants the rest of us to be informed.

"This is sort of the nursery area. This is where you find the small ones and the breeding pairs. The ones that are a bit bigger, and are going a little deeper, are the ones we're getting in the pots."

The green crab was first reported in North Harbour in August 2007. Since then scientists have been working to answer the obvious questions, like how long has the crab been here and what damage that has already been done?

"We think they've been here for maybe three or four years. They've taken over and eaten everything in sight," says MacKenzie. "In terms of biodiversity, on the beach here we're not really finding anything other than green crab. In other areas you would find a mix but here they've pretty much eaten everything that there is."

They've been infesting the Maritimes for several years now as well. The green crab originated in Europe. They eventually made their way to Maine, devastating the crab fishery there. They've invaded most of the shallow bays and estuaries of Nova Scotia and along the shores of Prince Edward Island.

On the West Coast, the green crab has invaded waterways from San Francisco to Vancouver Island.

The crab came to North American waters via ships sailing from Europe. The crab larvae will survive weeks in a ship's ballast. Once the ballast water gets dumped, the larvae move with the currents to the coast.

MacKenzie is fully aware that making this crab disappear is not a realistic target.

"If we can beat it back enough to where it doesn't substantially impact the eelgrass beds and the other things that would live here, I would consider that a success. There's no way we can get rid of it completely.

"We just need to beat it back enough to where it gives everyone else a fighting chance."

Phillip Sergeant, a research assistant with the Ocean Sciences Centre, has been diving in the waters of North Harbour. He's seen the bottom, and it's green.

"It's infested, absolutely infested. Last year we did a transect from the beach out 100 feet. We were trying to count crab along the line as we were going. They started popping up in just inches of water and there were so many I just couldn't keep track of them."

The way he sees it, unless you comb all the coastline beaches in the area, each year the juveniles will replenish the population.

John Boland, staff representative with the FFAW, says the group needs assistance from government and, more importantly, from local industrial developers.

"We're certainly not putting the blame on any particular parties for these crab here but there's no question it's the result of the industrial development taking place in Placentia Bay. There are all kinds of ships that go in and out of Placentia Bay and they come from all over the world, and that will only get worse. We can't just ignore it."

A full plan of action as yet to be developed beyond this point. Not only do they need to confront the situation at hand, they have to be ready for similar invasions.

"There's a lesson to be learned in terms of being ready. We are grasping at straws to deal with this. We need resources, we need help in order to fix this problem," Boland says.

"We can't just stay at this for three or four weeks and figure we've got it solved."

(Gavin Simms is a journalist with Transcontinental Media’s Packet newspaper, which is a contributor to the Sou’Wester.)