European green crab totals climb in Neah Bay, decline in Dungeness

Population captured near Blaine shows numbers growing inland

By Matthew Nash • October 16, 2019 1:30 am
Adrianne Akmajian, marine ecologist for Makah Fisheries Management, said this season her crews used shrimp pots to capture European green crab with much success. “We often catch at least 10-plus green crab in a single shrimp pot that we set in the main river channel (and a lot of Dungeness crab that aren’t legal size for keeping),” she said. This season, she and her crews captured more than 1,200 of the invasive green crab and anticipate trapping for them again next season while contemplating other efforts to limit or eliminate them. Photo by Adrianne Akmajian
Adrianne Akmajian, marine ecologist for Makah Fisheries Management, said this season her crews used shrimp pots to capture European green crab with much success. “We often catch at least 10-plus green crab in a single shrimp pot that we set in the main river channel (and a lot of Dungeness crab that aren’t legal size for keeping),” she said. This season, she and her crews captured more than 1,200 of the invasive green crab and anticipate trapping for them again next season while contemplating other efforts to limit or eliminate them. Photo by Adrianne Akmajian

Keep trapping or not: that’s the dilemma facing the Makah Tribe in Neah Bay.

Their totals for European green crab, an invasive species known for edging out local sea life such as Dungeness crab and eelgrass beds, surpassed their own high mark from last year.

From April 1-Oct. 2, Adrianne Akmajian, a marine ecologist with Makah Fisheries, and her crews caught 1,262 green crab between the Tsoo-Yess River, Wa’atch River and near Tsoo-Yess Beach. That’s more than 20 times the Sequim area’s totals.

Last year, the Makah Tribe captured 1,030 green crabs.

Akmajian said there is funding in place to continue trapping next year, but she questions to what level they’ll continue their efforts.

“It’s unlikely we’d eradicate them, but we can keep monitoring,” she said. “We have some ideas to do studies to track crabs. So for at least one more year, we’ll keep operating with trapping.

“We’re wondering if this is the new normal.”

They won’t begin officially trapping again until next spring, but Akmajian said she wonders if their numbers are higher because they’ve gotten better at trapping, such as using shrimp traps in larger river channels.

Akmajian said she sent green crabs for DNA analysis again to see where they might be coming from.

Of the crabs analyzed in 2017, she said most were from the outer coast. However, depending on the oceanographic conditions, they could have come from any direction, she said.

Local studies in Neah Bay continue of river otter scats to see if they’re eating green crab, Akmajian said, which could offer some local, natural mitigation.

Sequim-Dungeness

While Neah Bay’s totals climb, the Dungeness Spit appeared to host less green crab than last year.

Lorenz Sollmann, deputy project leader at the Washington National Wildlife Refuge in Dungeness, said his crews captured 57 green crabs this season, a decline from 69 in 2018 and 96 in 2017, when green crabs were first discovered there.

Sollmann said resource managers set 2,444 traps over 70 trapping days with a standardized catch-per-unit effort of 2.37 for 2019, compared to 2.55 and 2.56 the previous two years.

Neil Harrington, environmental biologist for the Jamestown S’Klallam Tribe, caught two green crabs in Sequim Bay this season as well.

Sollmann said he plans to continue

trapping again in April 2020. Resource managers began preventative trapping in 2001 along the Dungeness Spit but nothing was discovered until 2017.

Growing population

In September, resource managers reported additional captures this season including four in Samish Bay, five in Whatcom County and one on the San Juan Island.

Following early evidence of green crabs in Drayton Harbor near Blaine, resources managers with the Washington Department of Fish and Wildlife and the Washington Sea Grant Crab Team trapped 17 green crabs during a two-day rapid response in late September.

Resources managers said this is the largest amount of green crabs trapped in a short period of time along Washington state’s inland shoreline.

“Finding this many invasive green crabs so quickly in one area raises a serious concern that there may be an established and reproducing population in Drayton Harbor,” said Allen Pleus, WDFW’s aquatic invasive species manager.

Emily Grason, marine ecologist and Crab Team program manager, compared managing green crab to preventing wildfires.

“We keep a sharp lookout and respond quickly to small populations before they get too big to control,” she said.

“When even a single green crab is found, the first step is to quickly do more trapping to figure out the size and geographic extent of a potential population. Then we have more information to determine the best way to manage them.”

Grason said this time of year is the end of their trapping window because as the weather becomes colder, green crab are less likely to go for traps.

Between now and next trapping season, Grason said Fish and Wildlife plan to hold two stakeholder meetings in the Sequim area and along the I-5 corridor to discuss efforts, share information and strategize management plans.

Crab Team’s core funding is secured through June 2021 through the state, as it continues to coordinate early-detection monitoring sites across Western Washington, including the Lower Elwha Tribe at the Pysht River, Dungeness Landing, Washington Harbor and Jimmycomelately Creek in Sequim Bay and Discovery Bay, and Kala Lagoon and Indian Island in the Port Townsend area.

Beginning trapping

European green crab were first trapped on the West Coast in San Francisco Bay in 1989 and later confirmed in Washington waters in 1998 in Willapa Bay and Grays Harbor.

Fish and Wildlife staff partnered with Washington Sea Grant in 2012 to develop the early detection monitoring program after a large discovery of green crab in Sooke Basin on Vancouver Island.

Trapping in Neah Bay began in 2017 after a passer-by discovered a green crab near the Wa’atch River and reported it to Washington Sea Grant, leading to intense trapping efforts to catch 34 green crab.

Identification

Resource managers say if you find a live green crab or its shell in Washington, report it online to crabteam@uw.edu, but leave the crab in place to avoid accidentally killing native crabs. It is illegal to possess a live green crab in Washington to protect native crabs from cases of mistaken identity.

For more information about crab identification, visit wsg.washington.edu. For more about aquatic invasive species, visit wdfw.wa.gov/species-habitats/invasive.

Reach Matthew Nash at mnash@sequimgazette.com.

Sean McDonald with Washington Sea Grant sets a trap in California Creek in Blaine as part of ongoing assessment efforts looking for European green crab. Recently, green crab were found in high capture rates in the area resulting in intense trapping efforts to see how intense the totals were in the area. Photo by Emily Grason

Sean McDonald with Washington Sea Grant sets a trap in California Creek in Blaine as part of ongoing assessment efforts looking for European green crab. Recently, green crab were found in high capture rates in the area resulting in intense trapping efforts to see how intense the totals were in the area. Photo by Emily Grason

From April-October, Makah Tribal staff caught more than 21 times the amount of European green crab in Neah Bay than the Washington National Wildlife Refuge in Dungeness. Both groups of resource managers look to trap again next season as they look to limit and potentially eradicate the invasive species. Photo by Adrianne Akmajian

From April-October, Makah Tribal staff caught more than 21 times the amount of European green crab in Neah Bay than the Washington National Wildlife Refuge in Dungeness. Both groups of resource managers look to trap again next season as they look to limit and potentially eradicate the invasive species. Photo by Adrianne Akmajian