British Columbia

Help the DFO by spotting the invasive European green crab in B.C. waters

The European green crab has been established in the Sooke basin and along the outer West Coast for two decades and can make major changes in marine ecosystems.

The crab can be very destructive on eel grass meadows, an important herring and salmon nursery habitat

Though the European green crab is frequently green, they are not exclusively so, and they can also be brown or red. What distinguishes them from native crabs are its five distinct spines on each side beside the eye. (Submitted by Parks Canada)

The European green crab can have a very destructive impact on West Coast ecosystems, and the public can help Fisheries and Oceans Canada (DFO) by reporting any possible sightings in non-common locations to its tip line. 

Thomas Therriault, a research scientist with the DFO, says the European green crab arrived in West Coast waters in the late 1980s. 

"It arrived in San Francisco Bay in the late 1980s, most likely in packing material with either live seafood shipments or bait worms," Therriault said. 

When the crabs got dumped into the bay, they travelled up the coast reaching Oregon, Washington state, and eventually reached the southwest coast of Vancouver Island in the late 1990s.

The crabs, which are frequently green but not exclusively so, are distinguished by five distinct spines on each side behind its eye.

As an invasive species, the crab eats local clams, mussels, oysters, and competes with other native crabs at the juvenile stage, Therriault said. 

"They can really damage or degrade eel grass meadows," he added. "Those eel grass meadows are important nursery habitats for herring, juvenile salmon, which are obviously very important on this coast."

The DFO  started a coastwide monitoring program for European green crab in 2006, and since then the crab has spread up the coast. 

"They progressed up the west coast of Vancouver Island and into the Central Coast. They had largely been absent from the Salish Sea, and the North Coast including Haida Gwaii until recently," he said. 

"We don't know yet whether that's established yet. It's just a detection."

The public can help in this aspect, Therriault said, by reporting sightings of green crab in places where there haven't been established populations like within the Strait of Georgia, the Johnson Strait, the North Coast of B.C., the Prince Rupert area  and additional locations around Haida Gwaii.

He says these sightings can be reported to the DFO at in the Pacific region. Those reporting are encouraged to submit a photograph, a GPS location and date of sighting, and a note of any distinguishing features.

"We certainly want to make sure we're getting the actual European green crab, and we can help the public discern if it is some of our native species."

Listen to the full interview on CBC's All Points West:

The invasive European Green Crab has been responsible for major changes in almost every ecosystem it colonizes. For more than 20 years, the Green Crab has been established in the Sooke basin, and it has been seen along the outer west coast of Vancouver Island. But a conservation group in Tofino is worried the Green Crab is actively destroying even more habitat in Island waters. For more on this, Kathryn Marlow reached Thomas Therriault, a research scientist with Fisheries and Oceans Canada. 6:48

With files from All Points West


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