BC
Monique Keiran: 'Crazy, raging crab' gets its claws into Island
We were sitting outside the local joint, enjoying our morning dark-roast Arabica lattes — or dainty espresso, in Nature Boy’s case — when the guy at the next table put down his iPad and leaned over to mumble something to his companion.
“Hmm?” she said.
“I said” — and he raised his voice — “our problem with crabs is getting worse.”
That got her attention — and everyone else’s nearby. She tucked her chin into her collar and started whispering furiously at him.
“I mean Carcinus maenas — European green crabs,” he answered. “What kind of person do you think I am? No. Wait. Can we start again?”
Nature Boy leaned over and tapped her arm. “Ahem, I believe he’s talking about sea crabs. Like Dungeness crabs.” He turned to the guy, all disingenuous. “Are you a marine biologist?”
Nature Boy saves the day and maybe their date, but not, alas, the B.C. ecosystems where European green crabs have set up house.
They’re not the stuff of coffee shop dramas. They’re worse.
Carcinus maenas (“crazy, raging crab”) is considered one of the world’s worst invasive species. Native to the northeast Atlantic and Baltic Sea coastlines and found from northern Africa to Iceland, the aggressive crabs feed voraciously on shellfish such as clams, mussels, young oysters, small fish and even other shore crabs. They destroy marsh habitats by burrowing into the mud, and they obliterate eelgrass beds, disrupting these critical habitats, where juvenile salmon, herring, other fishes and native crabs feed and find shelter.
European green crabs are also hardy. Their early life stage, as larvae, lasts for 50 to 80 days, when they can drift great distances on ocean currents. The adults can survive out of the water for days, hiding in fishing gear or at the bottom of crates, buckets and boats. They tolerate a range of water temperatures and salinity levels, and thrive during warm winters.
Likely first introduced as larvae in ballast water in ships or within packing materials to eastern North America in the early 1800s, the crabs ate their way up and down that coast.
In 1989, they were spotted in San Francisco Bay, possibly brought there in boxes of live fishing bait.
Then, during a warm El Niño winter in the late 1990s, their larvae rode currents up the west coast. Small populations were detected in Oregon and in Washington, but large populations were swept into bays, coves and inlets along the west side of Vancouver Island.
They came. They saw. They ate. They liked.
By 2011, they had reached Bella Bella. They were found in the Sooke Basin in 2012. They made it to the San Juan Islands by 2016 and to Washington’s Drayton Harbor, near Blaine, and to Boundary Bay by 2017.
Since 2018, they have been detected in Esquimalt and Witty’s lagoons, along Salt Spring Island and the Sunshine Coast, in Nanoose Bay and in Haida Gwaii.
The governor of Washington state issued an emergency proclamation this year after more than 70,000 European green crabs were caught last year in the Lummi Nation’s Sea Pond, near Bellingham. Emergency measures are also in place for Drayton Harbor.
With B.C.’s $270-million (2016 numbers) shellfish-farming and wild shellfish industries as well as estuary ecosystems vital to the province’s herring and wild salmon populations at risk, urgency is required to chart, contain and control the crab’s expansion.
Fisheries and Oceans Canada has set up programs to detect and track the crab’s spread in Canadian waters. It trains and works with conservation groups and volunteers to set traps and identify and count crabs.
An education campaign reminds boaters and fishers to practise hygienic boat and gear care and to not transport water, mud and gear from area to area, and to report any sightings.
Regular beachwalkers can also report sightings. If you think you see a European green crab, take a photo but leave the crab where you found it. Email photos, date and location details to aispacific@dfo-mgo.gc.ca. Note that many native crabs are green, but European green crabs have five spines on each side of the shell.
As for that other kind of crab — those wingless, parasitic insects called lice are something else altogether.
keiran_monique@rocketmail.com
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