Kirsten Lie-Nielsen is a writer focusing on issues of climate and food. Her work can be found in The Guardian, Civil Eats and The Boston Globe. She lives in Maine, where she is currently working on a memoir.
CASCO BAY, Maine — It’s a humid summer day on an island off the coast of Maine. Thick air seeps into the cabin, making everything feel damp, even the white bedsheets that smell of salt and mothballs. Down by the cove at the forest’s edge, the dogs sniff along a strip of sand where the gently lapping waves wash ashore.
Perpetually chilly, this part of the Atlantic Ocean courses around the islands off Portland. Even in summer, I find it best to swim at high tide, after the briny bay has climbed half a dozen feet over sun-cooked sand and rock. But water temperatures in the wider Gulf of Maine have been steadily climbing — it’s an average of two degrees Fahrenheit warmer here than it was 30 years ago. In fact, the gulf is warming more rapidly than 99% of the world’s oceans due to bathymetric and atmospheric conditions.
Those two degrees of additional warmth are a shocking, life-altering change for some of the marine life in the intertidal waterways — including Maine’s primary edible ocean product, the lobster, which is showing signs of moving north in search of colder seas. Taking lobsters’ place as lucrative fishery offerings are bivalves — oysters, mussels, scallops — which appreciate waters a little warmer than lobsters do.
Green crabs, an invasive species that also thrives in warmer water, have proliferated as well. They come up in lobster traps and appear in the tide pools I used to squat down to examine as a child. And these days, in many spots along the coast, if you look down you’ll see their muddy green-brown shells scuttling off in all directions.
So prolific are green crabs on Maine’s coast now that they outnumber native rock and Jonah crabs, which they eat, along with snails, soft-shell clams and other bivalves that are vital economic products in a state that relies heavily on its fisheries. Even juvenile lobsters have been found in the stomachs of green crabs.
This has caused serious issues for businesses like Nauti Sisters Sea Farm, which floats in the water off Little John Island. Its rows of plastic oyster cages bob between buoys in the shifting tides. Each is home to a hundred or more growing oysters. Alicia Gaiero maintains the farm with her sisters, Amy and Chelsea.
Nauti Sisters uses fine-mesh floating oyster cages for larger oyster seed and bigger sunken cages for smaller seed. These bottom cages, or “condos,” as they’re called in the biz, are unfortunately accessible for the green crabs, which can simply crawl in and gorge on tiny, growing oysters. They also make the cages heavier, which gets problematic when you have to lift them out of the water dozens of times a day.
On a skiff out by the oyster cages in late June, Gaiero expertly hooked a buoy and hauled up one of this year’s bottom condos. “Last year we were so overwhelmed,” she said as she worked. “We just started filling crates with green crabs.” People sometimes would come to take them, she went on, but Nauti Sisters doesn’t have refrigeration and the green crab distribution network is inconsistent, so they don’t know who might show up looking for some, or when.
Gaiero plopped the condo onto the deck of the skiff. Crabs of all shapes and sizes scattered out. One green crab snapped its front pinchers in the air defensively. She grabbed it and tossed it into a five-gallon bucket. Like most oyster farmers, she and her sisters usually smash the crabs and compost their remains back on land.
Native to coastal Europe and North Africa, green crabs arrived in North America in the 1800s, likely via the ballast water of merchant ships. They can now be found on every continent except Antarctica, and are one of the 100 most harmful invasive species worldwide.
Viciously versatile, green crabs grow quickly, may reproduce multiple times in a season and are comfortable in a wide range of ocean temperatures. The harsh conditions that once kept their populations in check — really cold winters, sea ice — are growing milder. And as Marissa McMahan, the senior director of fisheries at Manomet Conservation Sciences, explained, in warmer waters, green crabs will reproduce more quickly and begin to do so at a younger age, causing a population explosion.
Green crabs are such aggressive predators they cost shellfisheries on the East Coast an estimated $22.6 million annually in lost revenue. “They love bivalves. They love soft-shell clams. They’ll beat up on small lobsters, they beat up on native species, they mow down eel grass,” Jason Goldstein, the research director at the Wells National Estuarine Research Reserve, told me. “So there really aren’t too many good things we can say about them, right?”
“Green crabs can now be found on every continent except Antarctica, and are one of the 100 most harmful invasive species worldwide.”
But for intrepid fishermen and creative chefs, there may be just one good thing to say about them: They can taste pretty good.
Humans can be very effective at controlling animal populations when motivated to do so. We have hunted native species to extinction, so one approach that scientists and chefs are experimenting with is the consumption of invasives — also known as invasivorism — to try to control their expanding numbers.
The strategy of “beating by eating” unwelcome creatures has been embraced around the world. Humans have reshaped entire ecosystems with their appetites.
One of the most famous examples is the Asian carp, sometimes called “the most hated fish in America.” They are well-established in the Mississippi River basin and found as far north as the Great Lakes region. High-jumping carp evade low dams and other attempts to control their population and they compete with local fish for resources.
Carp can have a muddy taste and are considered by many Americans to be a “trash fish,” but this is partly due to a misunderstanding. The muddy association may come from our tendency to associate all carp with the Asian carp’s bottom-feeder cousins. Some reports suggest the flavor of Asian carp, which feed typically on plankton and algae in upper levels of rivers, is rather light. And when properly prepared they can be tasty.
Similarly, the feral hogs that plague Texas and the Southern United States can be eaten just like any other pig. And if you’re a fan of the bright green seaweed salad often found at sushi restaurants and in Asian buffets, you are doing your part: The wakame variety of seaweed used in those salads is an invasive species that is, in my opinion, truly delicious. Other edible invasives include some species of crayfish, the nutria (a semi-aquatic rodent), lionfish and the armored catfish.
Many of these species are commonly consumed where they are native; distaste for them in new places is often cultural, due to their being unfamiliar to palates where they invade. All that’s required to enjoy them is a good recipe. And unlike some consumption that can come with a side of guilt, preparing an invasive species for the dinner table can bring a feeling of comfort in helping native habitats.
Although eating green crabs would make only a dent in their overall population, harvesting them is still a way to support the local community and ecosystem. This is part of the appeal for Evan Montellese, who got his green crab fishing license from the state for $10. He’s autistic and finds the experience of green crab fishing particularly satisfying — he keeps his own hours and can manage just fine with his kayak.
Montellese sets some of his crab traps off pilings at the wharf in Scarborough Marsh, just south of Portland. Others he puts in the marsh’s intertidal waters, paddling out to get to them. After participating in a research project with Manomet last year, he started reaching out to local restaurants about whether they were wanting any green crabs. “A lot of them were,” he told me, “and it just kind of grew from there.”
Maine’s waterfront can be a hard place for outsiders to start a career. The state’s fisheries are well regulated, with only a certain number of licenses for lobstering and commercial fishing. Of the state’s roughly 7,000 lobster licenses, many remain in the same family generation after generation. Few become available for new fishermen.
Many fisheries, particularly the cod and Northern shrimp fisheries, have suffered dwindling harvests as the gulf warms, and whether you want to fish in the deep sea or farm shellfish on the coast, the investment required to start from nothing is huge: boats to buy and maintain, traps to purchase, leases to obtain, license fees, mooring charges. And the chances of making a viable living are deeply uncertain.
But Montellese’s biggest challenge, at least at first, was convincing chefs to put green crabs on the menu.
Once named Bon Appétit’s Restaurant City of the Year, Portland has a high concentration of top restaurants and is a mecca for foodies. Seafood, for obvious reasons, is the city’s specialty.
If you want to eat a green crab, your primary problems are their tough shells and small size. Unlike with larger crab species and Maine’s iconic lobster, breaking a green crab shell at the joints will release only a thimbleful of meat. So cooking them and plopping them down on a diner’s plate is basically out of the question.
“One of the challenges is getting consumers used to the idea that green crabs are edible in the first place.”
Chefs are learning that there’s a better way to use them in the kitchen.
“They make a killer broth stock,” Damian Sansonetti, a chef and co-owner at Chaval, in the West End, told me. “We break them down, roast them, mix them with some tomato products. It’s intense.”
When I visited Chaval recently, Sansonetti opened the lid of a container to reveal a deep brownish paste that released a blast of fishy aromas. I touched a small dollop to my tongue, sparking an explosion of fervent briny, oceanic flavor. Sansonetti uses this concentrate as a flavoring agent in numerous sauces and broths.
Doing this with lobster or other crabs, which cost around $12 a pound, would not be the most cost-effective use of prized crustaceans. Green crabs, though — at $1-$2 a pound in Maine, according to Sansonetti — are ideal.
Farther downtown from Chaval, Jordan Rubin, a James Beard-nominated chef who runs the restaurants Crispy Gai and Mr. Tuna, echoed Sansonetti’s enthusiasm. “There’s not really meat you can use, but the flavor!” he said with excitement.
With green crabs that are big enough, however, you can crack into them and poke out freshly cooked meat. Another way to enjoy a green crab is if they’re harvested during their molt, when their shells are soft enough for teeth to break through. In Italy, green crabs are native and even prized, especially for preparing a dish called moeche, which involves battering and frying the soft-shell crab and often serving it alongside fried polenta.
But harvesting them at the right time is tricky. Their soft-shell stage lasts only about a day. “It can be a headache because it’s unpredictable,” Montellese told me. “There are a couple of people in Maine who are experimenting with harvesting the crabs [at the hard-shell stage] and keeping them until they shed, then selling them at that moment. It’s difficult from a sale or financial perspective, because they don’t all shed at the same time. Every crab is a little bit different depending on how fast they grow.”
Whether green crabs are soft-shelled or hard-shelled or boiled down into a concentrated paste, one of the challenges is getting consumers used to the idea that they are edible in the first place.
There are, however, potential uses for green crabs outside the kitchen. One is to use them as fertilizer. Lobstermen often grind up the bodies of green crabs they find in their traps and toss them in their gardens. Montellese is experimenting with a liquid fertilizer, trying different balances of crab to essential oils to get the smell right.
As invasive species continue to move north with warming oceans, the waters are muddied further by another crab.
Blue crabs — the star of Chesapeake Bay cuisine — have flat blue-gray bodies and dazzling sapphire legs. They can stretch more than 9 inches across, and when they shed they provide Marylanders with a delicacy that is as synonymous with Bay living as a lobster cookout is to Maine’s coastline: deep-fried soft-shell crab.
As a predator, blue crabs are even more alarming to oyster farmers and lobstermen than green crabs. Their larger size and aggressive hunting means they can consume small lobsters, larger shellfish and any other crab species they can track down.
As with green crabs, running a soft-shell blue crab business requires keeping them in tanks and a good deal of patience. But unlike with green crabs, the market for soft-shell blue crabs is established and lucrative, making the tank and time investment worth the trouble.
They’re already popular, Montellese told me, so if they do establish themselves in Maine, it will likely be easier to make a business out of harvesting and selling them. And, McMahan said, as they “start to exert more predatory pressure on green crabs,” they may even drive green crabs off.
Back on the island, away from the bustle of curious tourists at Chaval and Mr. Tuna and just a skiff’s quick journey past the floating cages of Nauti Sisters Sea Farm, green crabs darted sideways across a pebble-strewn beach made bare by the receding tide on one of the hundreds of islands in Casco Bay.
“Preparing an invasive species for the dinner table can bring a feeling of comfort in helping native habitats.”
With a bucket in one hand and a glove on the other, I scooped up a dozen green crabs in a few minutes. Their tiny claws snapped and pinched, but not tightly enough to break skin. I usually spotted them scurrying across mud that came up to my ankles, and as I parted the thick webs of seaweed that plastered barnacle-crusted rocks, a half a dozen scattered for the nearest dark corner. You have to be quick to catch one, but there are plenty for the taking.
Once I gathered enough, I rustled up a campfire with bits of dried driftwood. I warmed up a large pot of fresh water, then added the green crabs to the cauldron. From a cooler, I added vegetables and savory essentials — garlic, carrots, onions, a splash or two of wine and broth. After the water started bubbling, I let the dish simmer for over an hour.
A savory green crab stew goes nicely with a piece of crusty bread. I taste the sea and a certain sweetness that is unique to this little adventurous crustacean, a persistent tidal predator that is determined to make Maine its home.
