The Friends of Cortes Island (FOCI) have not found any European Green Crabs in Manson’s lagoon, and so far there’ve been no sightings north of Nanaimo.  

“We haven’t found any, that’s really good news, but we’ve been very pleased to partner with the Department of Fisheries and Oceans (DFO).  Hopefully, if we ever find them, we’ll be able to trap them out and stop them from harming the valuable habitat here,” explained Helen Hall, Executive Director of FOCI.

“We were contacted by DFO last year. They wanted to come onto the island as part of a project they’re doing with a lot of communities up and down the coast, to try and find out whether green crabs are spreading in this area. We set traps in Manson’s Lagoon twice last year, and very luckily we didn’t find any.”

“This year DFO came back and said this is a project they want to keep doing. They brought all the traps over, we trapped last month and didn’t find any.”

“It’s a brilliant learning exercise for our summer student, Manuel Perdisa and we have two volunteers, Penny and Claude, who have helped us on other projects.”

“This week the three of them went out with Patty Menning from DFO. They’re setting two types of traps,  a large prawn trap and smaller minnow traps. 12 traps were set in Manson’s Lagoon on one day and  the next day we went back. They took the traps out of the water and emptied them into a plastic container which had water in it. We  found lots and lots of Graceful Crabs. We’re actually measuring those crabs  as a recording exercise, but we also found some other interesting species, then we released everything back into the lagoon. We kept all those records and  that data is going back to DFO.”

According to Renny Talbot,  Aquatic Invasive Species Coordinator for Fisheries and Oceans Canada (DFO), there have not been any sightings north of Nanaimo in the Salish Sea area. 

CC: Where are you looking for European Green Crabs in my broadcast area?  

Renny Talbot: “We’re looking on Cortes Island and Quadra Island, as well as the Fanny Bay area and Comox. We’ve set up early detection monitoring programs, with local stewardship groups and with our First Nations partners, in those locations.”

CC: Who is your partner on Quadra?

Renny Talbot: “We have a representative, Patty Menning, who’s working with the We Wai Kai First Nation.” 

CC: What about Campbell River? 

Renny Talbot: “We don’t have a site in Campbell River right now.  We have done opportunistic trapping in that location, but we didn’t have a really good site to set up long term monitoring.”

“Our early detection monitoring program: it’s once a month and it runs from April to October.  They do a 24 hour soak. We’re looking for European Green Crab, but it’s also creating a baseline of intertidal crab, fish and other species we’re catching. So that if there is an invasion, we can really understand the ecological impact that’s occurring.”

“We are lucky that there’s  some quasi barriers,  with the Juan de Fuca as well as with the Johnson Strait, which have limited the entry of European Green Crab larvae into the Salish Sea.”

 “The larvae need to be in water that’s greater than 10 degrees Celsius to survive.” 

“With water temperatures below 10 degrees, they have limited success in survival. That’s similar to the Juan de Fuca Strait, in that the main inward flow from the outer coast is at depth and it’s quite cold. The more freshwater, more brackish water, less saline water and warmer water is at the surface and pushing outward. The colder water goes deep and that’s where the larva  is moving in on  currents and so they die.”

“The European Green Crab that we currently have in the Salish Sea,  both on the Washington side as well as on our side, are believed to have arrived as a result of the warm water blob back in 2015/16.”

“Washington was the first to have detections of European Green Crab after that blob phenomenon and they’re still dealing with that incursion now.” 

“We still have limited crab that we find in our Salish Sea. We respond to them quickly and to date, we’ve been able  to get a handle on all the populations that we found. We’re still picking away at one in Ladysmith that’s challenging. We don’t get lots, but every time we go, we seem to find a few.  So it’s a bit of a struggle there for us .

“In the Boundary Bay area,  there’s established populations right across the border in Drayton Harbour.  We get larval pulses that come up, and so they still do find them on occasion in that location.”

“There’s the odd one in Witty’s Lagoon, Esquimalt, which seems to come back. We find 1  every year, but we have an active monitoring program that  goes all summer long and we do eradication as soon as they pop up.”

“But Salt Spring Island, Penelakut, the Sunshine Coast: we’ve conducted responses right away and, to date, they seem to be successful.”

CC: How close have they come to Greater Campbell River/ the Discovery islands?

Renny Talbot: “Madeira Park on the Sunshine Coast would be the closest detection that we’ve had in that northern region, and nothing past Nanaimo on Vancouver Island.”

Helen Hall: “If the Green Crab gets in, it’s really bad news.” 

Renny Talbot: “European Green Crab are highly voracious predators. They eat everything. They compete  for food  with our native shore crab . They prey on bivalve species, and other shore crab – which includes juvenile Dungeness Crabs.”

Helen Hall:  “It goes into eelgrass, digs tunnels, and it eats the shoots. It can destroy eelgrass habitat and that’s one of the most important habitats in the marine environment. It’s a really important nursery for a whole lot of species, including juvenile salmon.

Renny Talbot: “They remove and excavate the old grass, destroying those old grass beds.  In addition to that, they excavate salt marshes and estuarine habitat features to find food, find invertebrates. Their process of finding food results in habitat destruction.”

CC: Do they represent a threat to salmon?

Renny Talbot: “Absolutely, salmon  are very dependent on estuarine environments (salt marsh benches, eelgrass beds) that European Green Crab have a tendency to destroy in their pursuit for food. In addition to that, they eat a lot of invertebrates and things that salmon also feed on  while they’re rearing in these estuary environments.”

“They’re native to North Africa and places in Europe. They move around the world through  human vectors, for the most part. The European Green Crabs on our coast first arrived in San Francisco Bay. The belief is that it arrived through a contaminated shellfish, or potentially ballast water.” 

“Once in San Francisco Bay, they moved up the coast with larval dispersion. Once they’re in that larva stage, after the egg stage, they move  in the ocean currents and they can survive in that planktonic stage for up to 90 days. So they can travel quite far distances.”

“They’re believed to have landed on our coast in around 1998/99, originally on the west coast of Vancouver Island. Now they’re spreading north.  They’re  in Haida Gwaii, in areas on the Central Coast of BC and into Alaska as well.” 

“We have no detections thus far in the Prince Rupert area, but we also have limited monitoring effort in that area. There hasn’t been a big monitoring push there yet, we’re getting there.”

“Then as you go to Northeastern Vancouver Island, we’re dealing with incursions up around Port Hardy and Port McNeill.  That’s not believed to be from European Green Crab coming up from the Salish Sea moving, it’s from European Green Crab coming around the tip of Vancouver Island and down into the Johnstone Strait, and then starting to establish itself in those bays.”

“We have active response programs up there with our local Indigenous partners, and we’re funding responses actively right now in all the main locations.” 

“I’d like  to point people to additional information on European Green Crab. We partnered with the Pacific Sound Foundation to help display  where European Green Crab sightings have occurred throughout BC.

“As well, there’s great information on how to identify European Green Crab and where to report European Green Crab. So for us, especially in the Salish Sea and the North Coast where they’re not established, having public reports of European Green Crabs is extremely helpful.”

“There’s obviously really good information on DFO’s website, but for that in-depth tracking of where the sightings are and some good pamphlets and things like that, go to the Pacific Salmon Foundation website.”  

“There’s also additional training, if people really want to become well informed European Green Crab enthusiasts. There’s some online training  that we’ve developed in partnership with the Invasive Species Council of BC.  They have an online training module specific to European Green Crab and the licensing processes and identification and habitat types and some really good information. It’s free online training that  people can do at their own pace.”

Helen Hall: “Last year when we started working on this project, we put up signs on all the docks around the island, to alert people to green crabs and how to identify them.” 

Patty Menning explained what to look for in a DFO video: 

“When I’m bringing up a crab trap, I can tell immediately that it’s a European Green Crab. Even if the crab might be discolored or black or even sometimes they can become very orange. Green crabs are very distinct and they have this sort of, I call it a diamond or triangular shape. The other way I can tell is it has five very distinct teeth on either side of the eye.”

“One, two, three, four, and five. One, two, three, four, five. These marginal teeth are very distinctive.” 

Renny Talbot: “If you are very confident that it is a European Green Crab, it should not be placed back in the water. Finding one crab usually means that there is more. One crab, one female juvenile, can hold 185,000 per spawning period, and they can spawn up to twice a year.”

“So one crab can produce a vast population, so it’s very important that even one crab be reported to us.” 

FOCI has a special request for Cortes Island residents.  

Helen Hall: “If you’re suspicious about a crab you’ve seen, we want to know about it. If you see any European Green Crabs, it’d be great if you can report those to us and then we can feed that data back to the DFO. You can get in touch at friendsofcortes@gmail.com to let us know.” 

Top image credit: Invasive European green crab is found at Grays Harbor National Wildlife Refuge, Washington – USFWS photo: Ryan Munes via Flickr (Public Domain)

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