At the University of Maine's Pilot Plant in Orono, researchers are developing value-added food products out of invasive green crabs. Credit: Linda Coan O'Kresik

Invasive green crabs wreak havoc on Maine’s coastal ecosystems and its industries because they are voracious and prolific. For years, researchers have puzzled over how best to manage invasive green crab populations. Could the answer be in prepared foods?

While long-standing efforts to promote eating green crabs have struggled to find their legs in Maine, researchers are working to develop ways to better harvest and prepare foods with the crab.

The idea isn’t without merit — or challenge. Soft shell green crab, considered a delicacy in other parts of the world, is delectable and profitable, but the window for harvesting is small. New England fishermen haven’t quite figured out how to spot molting crabs among the masses. Beyond that, picking meat from the small crabs is labor intensive and low-yield. The shreds of meat get mushy when cooked, so it hardly holds up in a lump crab cake.

Green crabs, however, do work in value-added products such as fish sauce and empanadas.

Denise Skonberg, associate professor of food science at the University of Maine in Orono, has been working with green crabs in her lab for over 15 years.

“There’s tons of money [in selling] softshell green crab, but only a tiny percentage of the green crab that you harvest [is] soft shell,” Skonberg said. “What do you do with all the rest?” You have to do something that’s value added in order to make it worthwhile.”

Related: Green crab tasting in Brunswick

Turning crabs into sauce

The Paoli one-step deboner and desinewer is primarily used for meat and poultry, but it works wonderfully for green crabs — getting the hard-to-pick meat out easily and pushing the idea of value-added products with the green crabs closer to reality. The process sounds like several hundred forks running through a garbage disposal, and the output — green gunk glopping out of one orifice as sludgy shards of shells exit another — lacks visual appeal, but to the researchers it’s beautiful.

For the group of three collaborators — University of Maine Ph.D. student Bouhee Kang, director Rob Dumas and his client Michael Sheahan — at the University of Maine’s Pilot Plant, who sent 50 pounds of green crabs through the deboner on an October afternoon this year, the results looking promising.

“This is the best yield I ever got,” Kang said, looking lovingly at the expanding pile of meat mush, which she calls “mince.”

Kang studies how to best turn green crabs into value-added products. Aside from being an expert green crab deboner, she also studies the nutritional and functional properties of green crab proteins. Sheahan, on the other hand, has a specific product in mind for this green crab mince: fish sauce.

After reading “The Noma Guide to Fermentation,” the East Sedgwick-based carpenter decided to try making garum, or fish sauce, out of green crabs. His home experiments yielded a thick, umami sauce perfect for stir fry or mixing with mayonnaise for a dipping sauce. He reached out to Pilot Plant to experiment with scaling up his production.

“It’s a win-win for everybody,” Sheahan said. “Chefs would be all over something like this. Selling green crab garum is the ultimate goal, [but] I’m in the early stages at this point.”

More saucy experiments

Sheahan is not the only person who thinks fish sauce has the potential to solve the green crab problem. In fact, his is not even the only green crab fish sauce project at the University of Maine Pilot Plant.

In 2017, Skonberg and other food scientists at the University of Maine published a recipe-development and feasibility-study on hardshell green crabs to find ways to make them more palatable and marketable. They tested a number of dishes and value-added products — Skonberg said green crab empanadas were especially popular among subjects — but none of them have made commercial inroads yet.

“A lot of people were interested in the research, but as far as I know, [the empanadas are] not commercially available,” Skonberg said.

Then, Portland-based chef Ali Waks-Adams contacted Skonberg for a project: green crab fish sauce.

“She thinks the fact that it’s local and it’s got this story to tell, there’s a big story about it that that would be desirable for the chefs in the Portland area,” Skonberg said. “It’s always cool when someone with the industry wants to move forward and commercialize something.”

Skonberg recruited Jennifer Perry, assistant professor of food microbiology at the University of Maine to help. She set up her own green crab fish sauce experiment at the Pilot Plant (“You probably smelled it before you saw it,” she said with a laugh) to test the food safety elements of the fermenting process.

“Fish sauce is not currently produced from any domestic seafood source,” Perry said. “We’re looking at something that can be expanded to commercial processing facility scale for maximum impact of removal on invasive species.”

Beyond the sauce

Fish sauce is a great option for green crabs, but there are still opportunities for more value added products.

“Fish sauce per pound is a high-value product, but you don’t need to use tons of it,” Skonberg said. “By breaking [green crabs] into multiple streams, you can get a lot more value for the harvested resource.”

She said a tiered approach would be ideal: high-value soft shell green crabs could be sold to restaurants, while some hardshell crabs could be minced for value added products like fish sauce or boiled down into stock, and whatever remains could go to the dogs — literally.

In April 2019, Angela Myracle, assistant professor of human nutrition, developed dog treats made of processed green crabs. She doesn’t need a deboner, though: she cooks and mashes whole green crabs, mixes them with flour and bakes them into biscuits.

“A dog is not as particular,” Myracle said. “If you grind it up, it’s not like you’re crunching on shell. It’s a healthy and nutritious treat. You’re getting the benefit from the calcium and fiber in addition to the protein that’s in the meat of the crab.”

Her experimentation shows that dogs like green crab treats, so she hopes their humans — especially ones from away — will, too.

“When people go on vacation, they want to take something back home to the family pet,” Myracle said. “People are really gung-ho about Maine-made stuff. We’re really trying to give the tourists something for their furry family members and be good stewards of the environment.”

The challenges that remain

Aside from the fact that her clientele walks on all fours, Myracle’s green crab value-added product is unique in another way: she is working on developing her own company. As Skonberg learned from her green crab empanada experiment, commercializing value-added green crab products is just as challenging as developing them.

“We’re researchers, not business people,” Skonberg said. “We need someone who can commercialize it because they say, ‘Hey, I think there’s a niche for it.’”

Another outstanding issue is developing a supply chain for green crabs to get them to the value-added producers and beyond is going to be essential moving forward. Skonberg said that organizations such as Green Crab R+D , a nonprofit whose mission is to encourage the harvest and consumption of green crabs to mitigate their invasive impacts, are working on building the relationships between fishermen and processors, but those bonds will need to solidify before value-added experiments can move forward in any meaningful way.

“There’s no supply chain because there hasn’t been demonstrated that there’s a market for them,” Skonberg said. “You need to get a supply chain in place so that someone can get it.”

Skonberg said that some producers worry about building a market around an invasive species such as green crabs — if the product does what it is intended to, shouldn’t the green crabs eventually disappear? — but she added that realistically, this shouldn’t be a concern.

“Not to be a downer, but I don’t think that harvesting green crab will lead to them disappearing,” Skonberg said. “They’re just too prolific. At this point, I’m not thinking that we can eradicate them based on what marine biologists say. By catching them, you prevent them from running amok.”