Healthy Rivers Ogunquit (HeRO) and the Wells High School Environmental Club launched a pilot project for youth citizen scientists, trapping over 4,000 green crabs between June and September of 2022. Funded by a Discovery grant from the Onion Foundation, the program aimed to engage future scientists while demonstrating proof-of-concept to the idea that summer tourists can be recruited to participate in data collection and biodiversity restoration for a tidal river.

Research Assistant Catherine Angis (Wells High School) talks with volunteer crabbers at a "Green Crab Patrol" session.

Like many estuarine ecosystems in coastal Maine, the Ogunquit river has been inundated by green crabs. These invasives not only prey upon and outcompete native species in New England rivers, they’ve also led to the degradation of salt marsh beds which provide important habitat and ecosystem functions for the watershed including storm buffering, drainage, and CO2 sequestration.

The project not only tracked the number of green crabs by site, but also investigated the size, sex, shell stage, and, egg-bearing status of each crab collected. HeRO found that the proportion of female crabs varied by site, information that might be helpful for harvesters looking to collect roe-bearing females during ROE season. The team also stressed that citizen science data collection was key for locating soft-shell crabs and egg-bearing females that might be underrepresented by traditional box-trap data collection methods.

HeRO board member Jake Lawlor recruits some citizen scientists to help collect the day's quota of 100 crabs.

Research Assistant Kendal Shiels (Wells High School) shows off a juvenile green crab - barely the size of her fingertip. Crabs this small would easily slip through a 1" wire mesh trap, but were hand-netted by citizen scientists for the survey.

“Egg-bearing females were found by citizen scientists throughout the summer, with the majority caught in the first two weeks of August. These crabs were netted by volunteers who sought them out amongst boulder and cobble-sized rocks, primarily at the Riverside site. A fertile female can have a cache of up to 185,000 eggs, so targeting and removing egg-bearing females in the colder waters they seek near the river mouth is a potential strategy to reduce the local green crab population.” - HeRO

Moving forward, HeRO hopes to collect more data on egg-bearing green crabs and collaborate with local chefs who could use collected crabs on their menus.

To learn more about Healthy Rivers Ogunquit and the project, check out their full report.

Youth Citizen Scientists Investigate Green Crabs in Ogunquit