Washington scientists are using information learned last year as they gear up for trapping the European Green Crab in Drayton Harbor this year.
A team of researchers from Washington Sea Grant, Northwest Straits Commission and Washington Department of Fish and Wildlife (WDFW) started setting traps the week ending April 16.
As researchers were setting up 364 traps and preparing for the upcoming year, WDFW European Green Crab lead Chelsey Buffington said they caught a total of five green crabs at their three main sites this year – two crabs were captured near the old Cherry Street pier, two at the mouth of Dakota Creek and one at the mouth of California Creek.
Since trapping didn’t begin until late May last year, scientists say they are excited for the longer trapping season to better understand the crabs in Drayton Harbor.
“It’s nice to get out on time and even if it’s not the peak season. It’s valuable information,” Buffington said. “Starting earlier helps us paint a picture of what the crab is doing seasonally.”
Washington scientists first discovered the invasive species in the muddy shorelines of Drayton Harbor in fall 2019, near the end of the trapping season.
If left unchecked, the European green crab could threaten native habitats and species such as Dungeness crabs, oysters and clams in Washington, where the crab has started settling along the shorelines in recent years.
Washington Sea Grant marine ecologist Emily Grason said Drayton Harbor has a lower crab population density than other coastal estuaries in the state like Willapa Bay and Grays Harbor near the Olympic Peninsula. Still, she says it remains a concern, especially as scientists trapped European Green Crabs in nearby Lummi Bay and Samish Bay last year.
“I am pleased with the level of effort the group was able to pull off last year,” Grason said. “There were a couple of hundred crabs, which is more than anywhere else in the Salish Sea.”
Over 250 crabs were caught in 2020.
As for the number of years it will take scientists to eradicate the crab in Drayton Harbor, Grason said that question is not yet possible to answer.
“It depends if green crabs show up in new cohorts coming from outside Drayton Harbor,” she said, adding that the number of young crabs will need to go down. “We’re on the road to figuring out how the European green crabs are moving around the Salish Sea.”
A new trapping location was set up this year at the mouth of Dakota Creek, where the same scientists discovered many young crabs when they began checking the area last fall.
“There was a substantial number of crabs coming from Dakota Creek so we wanted to make sure we assessed that more regularly,” Buffington said.
During the week ending April 30, scientists began adding traps to three areas along California Creek and three areas along Dakota Creek that will be checked at least monthly, Buffington said.
Two of the core sites used last year, the jetty near Blaine Marina and a small creek between Dakota and California creeks, were removed from this year’s core sites, Buffington said.
Buffington said the team plans to assess Birch Bay more after a crab was caught at the mouth of Terrell Creek in October. The team is also looking to do a large-scale assessment of tidal trapping in Drayton Harbor, which is a proposition that will require help from local boaters to check deep-water traps, Grason said.
The scientists are also looking for help from landowners who will allow the scientists to trap on property to ensure there are no trapping gaps in Drayton Harbor and nearby creeks have been checked for the green crab,
“Wherever we can get, we’re going to trap,” Buffington said.
Landowners can contact Chelsey Buffington about trapping on their property by emailing her at Chelsey.Buffington@dfw.wa.gov.