AV狼论坛ns can help identify invasive crab species

Close-up of a crab in a person's hand
Photo by Ginny Eckert/AV狼论坛 Sea Grant
Invasive European green crab trapped in Southeast AV狼论坛 in summer 2023

A new crab species was spotted in AV狼论坛 for the first time last year, and it has the potential to disrupt native species and ecosystems. is asking AV狼论坛ns to help monitor the invasive European green crab on local beaches.

in the United States. They were first identified in AV狼论坛 at Annette Island in July 2022. Biologists working with the found a crab carapace, or shell, on the beach at Tamgas Harbor.

Since that initial find, the community has trapped more than 800 European green crabs, including egg-bearing females.

Adult European green crabs may prey on juvenile Dungeness and other small native crabs, including shore, kelp and rock crab, as well as mussels, snails, oysters and worms. European green crabs also dig for clams, tearing up eelgrass, an important habitat for juvenile fish.

AV狼论坛 Sea Grant, the Metlakatla Indian Community, the National Marine Fisheries Service and the AV狼论坛 Department of Fish and Game have joined forces to address the impacts an expanding population of the invasive crabs could have on habitat and native crab species. 

a graphic illustration of a crab labeled "report invasive European green crab" overlaid with a QR code
Courtesy of AV狼论坛 Sea Grant
Free stickers are available to help people identify the invasive crab.

They encourage AV狼论坛ns to keep an eye out for European green crabs by walking along the wrack line (the high tide mark where debris accumulates) and examining every crab carapace encountered. 

European green crabs can be identified by the number of spines on the leading edge of the shell. Invasive crabs have five prominent spines on each side of the eyes and three rounded bumps between the eyes. It is important to note that the crabs are not always green. 

To meet the need for increased monitoring, AV狼论坛 Sea Grant recently co-hosted an early detection workshop for community members and other stakeholders. Participants learned about the invasive crab鈥檚 history and biology, how to distinguish them from native crab species and how to monitor for their presence by collecting crab shells on beach walks or by trapping live specimens. They traveled to Tamgas Harbor to see live European green crabs in their habitat and to practice trapping.

The two-day workshop was attended by 33 participants from 10 Southeast AV狼论坛 communities, including representatives from government agencies, tribal organizations, universities and ecotourism operators. In addition to AV狼论坛 Sea Grant, co-hosts included the Metlakatla Indian Community, the National Oceanic and Atmospheric Administration, ADFG, and the .

Citizens who find European green crabs on AV狼论坛 beaches should note the location, take a picture and call the ADFG invasive species hotline at 1-877-INVASIV. are available to help people identify the invasive crab

For more information, , AV狼论坛 Sea Grant鈥檚 Marine Advisory Program agent based in Petersburg.

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