Our Vineyard waters are known for their delectable shellfish. They are vital to the Island’s economy, culture, and environment. But commercial and recreational shellfishermen have a problem — a big one. The invasive European green crab threatens juvenile shellfish not just here but up and down the East Coast. According to a New York Times article (“Invasive Crabs Have Taken Over New England. One Solution? Eat Them,” Jan. 31), green crabs have also established themselves in the Pacific Northwest, Japan, South Africa, South America, and Australia.
The Latin name for the European green crab is Carcinus maenas, which translates as “raving mad crab,” and gives some insight into the personality of this invasive crustacean. These small but voracious creatures are, as Sandy Cannon-Brown’s new documentary title states, “One Bad Crab.” The film will premiere at the M.V. Film Center on Sunday, March 9. She says, “My film uses a local critter to illustrate the universal threats to ecosystems caused by invasive species and climate change.”
Cannon-Brown, a Vineyard Haven independent documentary filmmaker, first became intrigued with the topic after reading an article by Nelson Sigelman, writer and Tisbury shellfish department assistant, “One Bad Crab: Can the Invasive Green Crab Be Stopped Before It Decimates the Vineyard’s Shellfish Industry?” in the Martha’s Vineyard Magazine. Sigelman, who narrates the film, speaks about the potential for the green crab to alter the ability to gather shellfish: “I’d never given much thought to the green crab. It was, I thought, just another crab. But the more I learned about this creature, I realized it was like a college football team hitting an all-you-can-eat buffet. Once it gets into a marine environment, it eats anything in its path.”
To make matters worse, green crabs destroy precious eelgrass. Martha’s Vineyard Shellfish Group Executive Director Emma Green-Beach says, “As they look for food, they will end up snipping and pulling up the eelgrass. Eelgrass habitat is critically necessary nursery space, especially for bay scallops and other economically and ecologically important species.” The green crabs also create burrows as they forage for juvenile shellfish, destabilizing salt marsh banks. Because the species proliferates almost unchecked, with a single two-inch female producing more than 168,000 eggs, the problem keeps growing.
The little crustaceans are tenacious. The New York Times Magazine article states, “Adult European green crabs can live 10 days or more out of water.” Although very frigid water for weeks at a time can help hinder the green crabs’ proliferation, it is unsurprising that, as the film points out, research indicates that climate change contributes to their spread.
“One Bad Crab” was shot primarily on the Vineyard, and features those at the forefront of the efforts to protect the Island’s valuable shellfish resources, who, along with Green-Beach, include Edgartown Shellfish Constable Rob Morrison, Chilmark Shellfish Constable Isaiah Scheffer, and Tisbury Shellfish Constable Danielle Ewart.
Cannon-Brown shares the various efforts of the towns’ shellfish constables to wage battle against the green crabs as they try to raise and protect the juvenile shellfish they plant in the Island’s waters. Green-Beach explains that for $40,000 apiece, each town receives a portion of the 10 million quahog, 20 million scallop, and 5 million oyster seeds the hatchery produces a year. Their survival to adulthood depends on their size when they are released, the quality of the water, weather, habitat … and predation.
Cannon-Brown looks at different ways the constables and those in other parts of the East Coast are trying to mitigate the problem. Some, like Chilmark Constable Isaiah Scheffer, regularly set some 100 traps in the areas where he releases quahog and scallop seed. Although he pulls up more than 1,000 crabs per week in the summer months, the numbers are inexhaustible.
William Cameron Walton, professor of marine science at the Virginia Institute of Marine Science, did his dissertation on green crabs on the Vineyard. He found that traps didn’t affect the numbers of the green crab population, but did improve the survival rate of quahogs by about 10 percent. However, eradication appears to be a losing battle, as we learn in “One Bad Crab.” A study by a team from the University of California, Davis, found that after a 90 percent eradication of green crabs in a small estuary in central California, the population increased by 30-fold the following year.
Edgartown Constable Rob Morrison says, “If you wanted to kill green crabs every day, all day, you couldn’t make a meaningful dent in the population.” Instead, he focuses on propagation in Katama Bay, planting quahog seed in peastone beds filled with gravel, material the green crabs don’t like to sift through.
Cannon-Brown casts her net wide when looking at other efforts to deal with the green crab challenge. As the New York Times article suggests, some people are turning the crustacean into a culinary option. Mary Parks, founder and executive director of greencrab.org, whose motto is “Problem to plate: Let’s eat the invasive green crab,” promotes restaurants that serve green crabs on the menu, as well as recipes for spicy curry green crab, green crab–tomato soup, and green crab scampi.
Others, including retired Tisbury harbormaster John Crocker and Tisbury School Principal John Custer, are using green crabs as bait. They can also be broken up and used successfully as nitrogen-rich fertilizer.
There is clearly no single solution to the serious threat green crabs pose. On the Vineyard, Cannon-Brown says, “I don’t think it’s a losing battle. I think there just has to be a new mindset on how we deal with them. I think what the Island is doing to try and work on propagation and figure out how we can grow our shellfish without losing them all to the green crabs is an excellent start.” Ultimately, Cannon-Brown’s film is a marvelous catalyst to start the critical conversation for us all.
“One Bad Crab” premieres at the M.V. Film Center on Sunday, March 9, at 4 pm. Martha’s Vineyard Shellfish Group Executive Director Emma Green-Beach will moderate a discussion following the screening with a panel that includes Edgartown Shellfish Constable Rob Morrison, Mary Parks, founder and executive director of greencrab.org, and retired Edgartown Shellfish Constable Paul Bagnall. Green crab broth will also be served. For tickets, visit mvfilmsociety.com/2025/01/one-bad-crab.
