European green crab increase warrants emergency actions

A large European green crab. Green crabs may also be yellow or orange in color, especially on their underside.

The European green crab (Carcinus maenas) is a globally damaging invasive species that poses a threat to Washington’s economic, environmental, and cultural resources. The European green crab is classified as a prohibited level 1 species in Washington because of its high invasive risk and high priority for prevention and expedited rapid-response management actions.

If you find a suspected European green crab or its shell in Washington, report it as soon as possible. Download the Crab Identification Guide and take pictures to confirm identification, then please release where you found it. At this time we are not asking the public to keep or kill suspected green crabs. This may sound counterintuitive but is intended to protect native crabs from cases of mistaken identity.

More information on identifying and reporting European green crabs is available on the Washington Department of Fish and Wildlife (WDFW) website and from Washington Sea Grant.

Emergency Proclamation and Funding Request

Gov. Jay Inslee issued an emergency proclamation on Jan. 19, 2022 to address the exponential increase in European green crab populations within the Lummi Nation’s Sea Pond and outer coast areas.

“We welcome this support from Gov. Inslee, and we are working on next steps in coordination with tribal co-managers, other management partners, and stakeholders,” said Allen Pleus, WDFW’s Aquatic Invasive Species Policy Coordinator.

WDFW’s Aquatic Invasive Species (AIS) Unit has determined that the $2.3 million appropriated by the 2021 State Legislature for European green crab management in the 2021–23 biennium is not sufficient to successfully control these exploding populations. This poses an imminent danger of these invasive crabs seriously threatening the environment, economy, and human well-being of Washington state.

Working with the Governor’s office, the Office of Financial Management, tribal co-managers including the Lummi Nation, Makah Tribe, and others, Washington Invasive Species Council and Washington Sea Grant, WDFW has revised its budget to reflect a later start and is requesting $8,568,000 from the State Legislature during the 2022 supplemental session to control increasing European green crab populations. In this request, $4,573,000 would pass through to the Lummi Nation, Makah Tribe, and other partners, and $3,995,000 would be used by WDFW.

Of these funds, $2,472,000 would be used to implement highest priority emergency management actions this fiscal year, including immediate increased population control actions at the Lummi Sea Pond. In fiscal year 2023, the remaining $6,096,000 would support continued European green crab emergency management actions. Working with partners, WDFW also seeks to ramp up outreach to stakeholders including the shellfish industry and recreational crabbers, local communities, and the public to support green crab identification and reporting.

WDFW will now be working with Washington’s elected leaders to support funding to implement emergency actions to control increasing European green crab populations and prevent their spread. Continue reading for updates from 2021 European green crab monitoring and trapping.

Counting the five “teeth” on either edge of their shell is the best method to distinguish green crabs from native shore and kelp crabs. Photo by Jeff Adams, Washington Sea Grant.

European Green Crab Populations Increasing

European green crabs are voracious predators and can have devastating impacts to native species and habitats as documented in their global invasion history. In the Pacific Northwest, those impacts include predation on shellfish and destruction of critical habitat such as eelgrass beds and estuary marshes.

These ecological impacts could significantly impact juvenile Dungeness crab populations, salmon recovery, Southern Resident killer whale recovery, shorebird food supply, and ultimately affect the overall health and resiliency of Puget Sound. Of equal importance, these impacted natural resources are part of the cultural identity of tribes and people of Washington and disproportionally affect endangered species, tribal treaty and cultural resources, small businesses, and low-income communities.

WDFW’s Aquatic Invasive Species Unit’s European green crab management actions in 2021, in coordination with tribal co-managers, shellfish growers, and other partners, have identified an exponential increase in European green crab populations within the Lummi Nation’s Sea Pond and outer coast areas including Makah Bay, Grays Harbor, and Willapa Bay.

A cooler full of invasive European green crabs trapped by WDFW and Lummi Nation co-managers in 2021.

Lummi Sea Pond Infestation

The Lummi Sea Pond (LSP) is located on Lummi Nation sovereign lands and WDFW has provided significant technical and funding support to the tribe in managing this situation since first detection in 2019. The LSP is a 750-acre diked intertidal area within Lummi Bay created in the 1970s to support Lummi fish and shellfish aquaculture programs.

European green crabs were first documented in the Salish Sea at Sooke Basin, British Columbia in 2012, in the San Juan Islands in 2016, and in Lummi Bay in 2019. Original infestation of the LSP is assumed to be from outer-coast larval settlement into the pond. With 86,028 EGC captured in 2021, the European green crab population in the LSP represents exponential growth since 2020, when only 2,670 were captured, and an imminent danger to the Lummi Nation and greater Salish Sea ecosystem.

Aerial of Lummi Sea Pond and EGC trapping locations for the week of Oct. 8, 2021.
Larger dots represent higher catch rates. Photo courtesy of Lummi Nation.

On Nov. 23, 2021, the Lummi Indian Business Council passed a resolution declaring the European green crab invasion a disaster. The resolution details the immediate and significant threat of European green crabs, establishes a Lummi task force to play a leading role in confronting the invasion, and highlights the need for resources to support the development and implementation of a comprehensive response strategy.

This year, WDFW began supporting the Lummi Nation in May with maximum cooperative trapping effort applied in September and October as capture numbers rose dramatically over the summer. Staff resources dedicated to LSP efforts included three Lummi Nation staff and up to six WDFW staff pulled from coastal and Salish Sea efforts. Combined Lummi/WDFW equipment included up to 500 traps and three watercrafts. During this period, capture rates averaged around 10,000 crabs per week.

Data showing the number of European green crabs captured in 2021 by WDFW, tribal co-managers and other partners in Washington’s northern Salish Sea.

Based on our experience and data shared by the Lummi Nation, WDFW concludes:

· European green crab are well-distributed across the Lummi Sea Pond, composed of multiple age classes, and are successfully reproducing.

· Control of the LSP European green crab population is still feasible.

· Failure to quickly respond to the LSP population could result in rapid loss of European green crab management control in the Salish Sea as a whole.

· Full deployment of Lummi and WDFW resources during September and October were not sufficient to see reduction in populations. WDFW cannot sustain full deployment at the LSP under present resources as it would significantly enhance European green crab invasion risks and harm statewide.

WDFW staff and partners trapping for European green crabs at Padilla Bay near Anacortes in August 2021.

Coastal Infestation Update

Coastal capture data alone does not provide the full picture as 2021 numbers in the table below are mostly reflective of the WDFW’s focus on assessing marginal habitat and filling in gaps to gauge the extent of European green crab invasion instead of focusing regional trapping efforts towards catching the most invasive crabs possible.

However, a significant portion of the green crabs caught during the season came from a few targeted removals in “hotspot” areas. For example, at the end of the season, WDFW, in coordination with the Shoalwater Bay Tribe, Pacific County, and Washington Sea Grant (WSG) captured ~2,000 crabs for a two-night effort in Tokeland area and WDFW, in coordination with WSG, captured ~1,300 crabs in a two-night effort at Ocean Shores.

This is similar to catch-per-unit effort we saw at the Lummi Sea Pond, which is why we believe there has been exponential European green crab population growth in these coastal areas since 2020. The Makah Tribe’s trapping efforts in 2021 were also limited in focusing on research, and COVID closures prevented enhanced support from WDFW.

Data showing the number of European green crabs captured in 2021 by WDFW, tribal co-managers and other partners in areas of the Washington coast.

Based on our experience and data shared by coastal co-managers and partners, WDFW concludes:

· European green crabs are well-distributed across these coastal basins, composed of multiple age classes, and warming waters are creating more opportunity for larval invasion from other West Coast populations.

· Control of European green crabs in coastal areas is still feasible but likely requires re-focusing efforts on protection of sensitive habitat areas and aquaculture resources.

· Failure to control protected resource areas could result in rapid loss of habitat for critical species and impacts to aquaculture products.

· Current funds provide only two seasonal technicians to support WDFW and one for Washington Sea Grant, which are not sufficient for effective population control across the coastal region.

Stay tuned for further updates as we prepare to ramp-up European green crab monitoring, trapping and public outreach and identification efforts in the spring of 2022!

WDFW staff and partners conduct European green crab trapping in 2021 at Drayton Harbor near Blaine.

The Washington Department of Fish and Wildlife is dedicated to preserving, protecting and perpetuating the state’s fish and wildlife resources.

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The Washington Department of Fish and Wildlife

The Washington Department of Fish and Wildlife

The Washington Department of Fish and Wildlife is dedicated to preserving, protecting and perpetuating the state’s fish and wildlife resources.

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