Turning the Invasive Green Crab into an Opportunity

Bella Dziak
Jul 21
3 min read

Shell + Claw: A Fisherman-Led Solution to an Ecological Problem

The European green crab is an invasive species that has been disrupting New England’s coastal habitats for over a century. Likely introduced by merchant ships in the 1800s, they’ve since spread up and down the coast. These crabs are notorious for devouring baby clams, mussels, and oysters, and destroying eelgrass beds that young fish need to survive. This damage doesn’t just hurt marine life, it accelerates erosion and undermines coastal resilience. With warming waters causing green crab populations to explode, researchers, fishermen, and coastal communities are grappling with how to respond.

One innovative solution is coming from Shell + Claw, a green crab and oyster aquaculture business co-founded by marine science teacher Mike Masi, who worked as a sternman for several years, and Sam Sewall, a fourth-generation lobsterman who has been fishing since he was around 10 years old and is now 28.

While teaching marine science at York High School, Mike launched a hands-on research project that had students trapping green crabs in the York River, analyzing size, sex, and trap location data, and developing their own scientific papers and proposed solutions. One of his students, Sam, was already an experienced lobsterman. After reconnecting at a York Lobstermen’s Association dinner, the two started talking about whether they could take green crab research a step further.

Soon after, Shell + Claw was created. With support from New Hampshire Sea Grant (particularly Dr. Gabby Bradt, Aquaculture/Fisheries Specialist, who was instrumental in teaching them how to identify pre-molt crabs), Mike and Sam began developing their model. While NH Sea Grant did not help secure their lease, they helped build the knowledge that made the project viable. The team secured an aquaculture lease in the York River, the first and only lease in the region to list green crabs as a species to be cultivated, which was designed to raise oysters and molt green crabs for commercial use. Their goal: turn an invasive threat into a profitable, sustainable seafood product.

Now, having just completed their fourth year, Shell + Claw continues to sell soft-shell green crabs to a growing network of restaurants. The process is no small feat: the team fishes with around 30 traps, sorts crabs by sex (only males molt in spring, while females molt later in summer or fall), and holds pre-molt crabs in specialized “crab condos” until they shed their shells. Once molted, the soft-shell crabs are sold to chefs who prepare them in dishes ranging from fried or sautéed crabs to broths and stocks made from hard shells.

While green crabs are also used seasonally as bait for species found in southern New England, like conch and tautog. Those markets are inconsistent and limited. Shell + Claw’s culinary approach extends the value of green crabs and demonstrates how they can contribute to a more sustainable and economically viable fishery, one that could support fishermen year-round.

Mike sees a bright future for the green crab industry, but he emphasizes that long-term viability will require more than bait and soft-shell sales. Expanded processing capabilities, new product development, and more efficient harvesting techniques will be essential to scaling the fishery and unlocking its full economic potential.

Shell + Claw is laying that groundwork. With science, grit, and collaboration, they’re turning an ecological challenge into a new opportunity for New England’s working waterfront. Mike’s passion for education, sustainability, and stewardship of the sea shines through in everything he does. His work exemplifies how local leadership and applied science can work hand-in-hand to protect and revitalize our coastal ecosystems.