One of the world’s most evasive species has been found on Whidbey Island in small numbers, but a collaboration of state experts and volunteers might help to ward off the threat.

Sound Water Stewards, a Freeland-based nonprofit, in collaboration with the Washington Sea Grant and Washington State University, are training citizen scientists on how to conduct molt surveys and join the fight against the European green crab, which is considered a threat to Salish Sea habitats.

European green crabs are native to Western Europe from the Baltic Sea to North Africa, said Chase Gunnel, communications officer with the state Department of Fish and Wildlife, and were brought to the East Coast of the U.S. in the 19th century on ships. The first place they were found on the West Coast was San Francisco Bay. Since the 1980s, these crabs have moved north, likely because of El Nino. They first appeared in the Salish Sea in the 1990s, according to the state.

They live in shallow, near-shore intertidal areas, eating native shellfish like clams and devastating estuaries and eelgrass beds. State officials, partnering with local tribes and shellfish growers, have recorded them in small numbers on the west side of Whidbey and in much greater numbers in the Lummi Sea Pond and on the San Juan Islands.

European green crabs pose a threat to shellfish harvesting and salmon forage fish recovery among a chain-reaction of impacts to the ecosystem. Green crabs are diggers, consuming 40 small clams a day and other crabs its own size.

The goal of Sound Water Stewards’s program is to nip green crab expansion in the bud and build a dataset for green crabs and other mobile organisms to provide a greater understanding of Island County’s coastal ecosystem.

There is almost no hope of completely eradicating green crabs from Washington, Gunnel said, as Oregon and California’s numbers are too high, but they hope to be able to control the expansion.

Stewards comb along the wrack line, where the high tide pushes the lighter ocean debris, looking for molts — when crabs shed their exoskeleton, said Tabitha Jacobs-Mangiafico, Whidbey coordinator for the nonprofit.

The biggest piece to learn is European green crab identification, she said.

For starters, not all European green crabs are green, and there are native crab species in the Salish Sea that appear green. The best way to identify European green crabs are the five points on each side of its shell, she said.

Surveying molts is easier than up-turning rocks and chasing down live crabs, she said. In four-person teams, surveyors scour the beach for 20 minutes, logging the data into an app.

Green crabs on Whidbey were first detected at Lagoon Point by a survey team including the Sound Water Stewards. Volunteers sprung into action, placing 114 traps along the coastline to find only one more green crab.

While they haven’t recorded additional green crabs, the surveys show trends over time for native crab species as well.

Washington Sea Grants utilizes this data for all kinds of research. While green crabs have so far not been spotted elsewhere on Whidbey, these surveyors are on the frontlines of their expansion.

The next Whidbey crab identification training session is in August. For more information, visit soundwaterstewards.org/molt-search-updates.

(Photo provided) The goal of Sound Water Stewards’s molt search program is to nip green crab expansion in the bud and build a dataset for green crabs and other mobile organisms to provide a greater understanding of Island County’s coastal ecosystem.

(Photo provided) Sound Water Stewards, a Freeland-based nonprofit, in collaboration with the Washington Sea Grant and Washington State University, are training citizen scientists on how to conduct molt surveys and join the fight against the European green crab.