Summary
In early August KBNERR's Harmful Species Program collaborated with Seldovia Village Tribe, US Fish & Wildlife Service, and Community Council Member Michael Opheim to deploy over 60 traps as a practice run for assessing an invasion of European green crab.
KBNERR along with local partners and trained community monitors have been on the lookout for invasive European green crab (EGC) in Southcentral Alaska since 2000. Invasive EGC are listed as one of the top 10 most unwanted invasive species in the world. They can destroy nearshore nursery eelgrass habitat, increase erosion of soft sediment shorelines and banks, outcompete native crab species and dramatically decrease bivalve abundances where they become established. EGC first arrived on the west coast of the United States in 1989 to San Francisco Bay Estuary and have steadily invaded farther north, and south, in subsequent years. The first detection of EGC in Alaska came in 2022. This summer, following the favorable El Nino conditions of 2024, EGC have been detected in numerous new locations in Southeast (SE) Alaska. Due to limited state resources allocated for EGC invasion assessment and response we do not know the current extent of EGC invasion in Alaska.
The crab’s primary mode of invasion is through larval transport in coastal currents, however several invasive EGC range expansions were due to transportation of adult EGC through human activity. The Alaska coastal environment from SE through Southcentral and into the southern Bering Sea is suitable for EGC settlement and establishment. Due to their proximity, expansion risk, and environmental suitability KBNERR has taken an active role in statewide EGC outreach, education, planning and preparedness. KBNERR Harmful Species Program works with local partners and Community Monitors to increase EGC preparedness in Kachemak Bay. KBNERR staff, partners and community monitors have been setting traps for the early detection of EGC since 2000. We also store traps for rapid assessment should EGC be detected in Kachemak Bay; these traps can be deployed to partners throughout Kachemak Bay including Seldovia Village Tribe, Chugach Regional Resources Commission, US Fish & Wildlife Service, and others to assess the level of invasion after first detection.
To increase regional capacity and preparedness, KBNERR organized an exercise in Seldovia Bay with the goal of setting and retrieving 100 traps over two days in early August, 2025. Three teams went out with 30-40 traps each to intertidal habitats likely to support EGC: 1) Seldovia Slough and associated waterways, 2) Head of Seldovia Bay and 3) Hoen’s Lagoon. After minor weather delays and boat motor issues, the teams successfully set over 60 traps. Deployment efficiency varied and highlighted the importance of having local knowledge and experience when conducting field work. Three take aways are: 1) gear preparation and familiarity reduce field time and mishaps; 2) experience and flexibility are key for successfully deploying a large number of traps in our bay with big tidal swings; and 3) teams of 3-4 can effectively deploy and retrieve up to 40 traps in a tidal cycle. These lessons learned and data collected will inform next steps in regional preparedness and planning to respond to EGC, should they arrive in Kachemak Bay, ultimately minimizing the impacts this aggressive invader has on the local ecosystem, culture, and economy.
KBNERR is an active partner of the Alaska Invasive Species Partnership, a partnership of Tribal, federal, state, private, and non-profit organizations working together to provide statewide leadership to prevent, detect and manage invasive species in Alaska by facilitating and fostering invasive species awareness, knowledge and information sharing, and collaboration among diverse stakeholders.
