It took 200 years of dealing with with the invasive European green crab before American scientists finally decided to head back to the crabs' source. And when they did, they discovered that the invasive scourge of our estuaries is a straight up Italian delicacy.
Watching Gabby Brandt, a University of New Hampshire marine scientist, detach a green crab that had vice-pincered itself onto the skin between her thumb and forefinger — calling it a “brat” once she had it off — you might ask why she would want to study them.
Up here in the Northeast, green crabs are absolutely everywhere. If you wade into the ocean and find a crab just below the low-tide line, it’s probably a green crab. Gabby thinks that in terms of overall number of crabs, they’re probably the most abundant in our waters. They’re from Europe, but have been on the East Coast of the United States for 200 years. They’ve invaded Australia, South Africa, the West Coast of the U.S., and South America. In other words, they’re now on five of the seven continents.
“They find a nice niche, they out-compete everything else, they ruin everything they see.” Gabby says, “Up in Maine they completely decimated the soft-shell clam industry.”
However, as you and I and anybody who likes seafood are aware, crabs are delicious. A friend of Gabby’s from Louisiana pointed this out several years ago: why not eat them as soft-shell crabs?
Soft-shells are simply regular crabs that have shed their shell as part of the growth process. For a few days after they molt their whole body is soft and you can eat the whole dang thing. Crabbers who sell these tasty little morsels catch them when they’re still hard, and then watch for the (obvious, at least when it comes to the most popular crabs) signs of an impending molt. These “buster” crabs are separated out into their own cages — jokingly called crab condos — because the soft crabs are vulnerable to being torn to pieces if kept in a tank with others, and then checked every day. As soon as the molt happens the crabs are rushed to market or to a restaurant, because their shells will harden again in anywhere from a day to a few days.
They are delicious, and people will pay top dollar for them, but the whole process of getting a soft-shell crab is premised on being able to identify the crabs that are about to molt, and Gabby Brandt realized nobody had any idea what to look for in these green crabs.
Looking for the Signs
I’ve joked that this Eat the Invaders segment rarely offers a good solution to the problem of invasive species because it often seems unlikely that we will begin to eat these pests at the scale necessary to put a dent in their population. But green crabs come up in traps by the hundreds sometimes. So I can imagine a world where there were enough overlapping markets — green crabs as lobster bait, green crabs as artificial bait, green crab roe, green crab mulch, green crab compost — to support a enough of a fishery to knock the population back. But to really get fishers interested, to really start hauling them in huge quantities off the seafloor, it would be nice to have a high end market. And soft-shell crabs can sell for $20 to $40 a pound. (Compare that to Lobster, which can float from between $6 to $12 a pound.)
The first year that Gabby tried to figure out how to identify which green crabs are about to molt she caught a bunch of them, and sent them to her friend’s lab down in Louisiana to be monitored for morphological changes — physical changes. “My colleague down there had it in her tank for... I don't know... four or five months, and they got 1 to molt.”
So there goes one year.
In year two, they decided to keep the crabs in their own tanks and take constant pictures of them every day so they could study the molting process. They started by trying to trap fifty males and fifty females, but couldn’t find any males because they started trapping in the wrong time of year. “We took many many many pictures, and we only got one molt… again.”
Another year gone.
Year three. They trapped a bunch of females, this time in the right time of year to observe the female molt. “And we got 80% of our females to molt,” Gabby says, “Took pictures. We have a timeline when we caught them to the time they molted and we went back and looked for morphological characteristics and... nothing.”
From what Gabby’s lab could observe, European green crabs offered absolutely no clue as to when they were about to shed their shells.
Asking the Masters
Around the same time that Gabby was going through years of frustration, Marissa McMahon — scientist from Maine that works with a non-profit called the Manomet Center — had a conversation with an acquaintance named Jonathan Taggart, a fine arts conservator who spent a lot of time in Venice, Italy.
“And he was in Venice, and he was eating deep-fried, soft-shelled green crabs,” Marissa remembers, “And so he came to me and said, ‘Why aren’t we doing this here?’”
It’s a little bit boggling to think about this, but green crabs invaded America in 1817. So it was 199 years from that date before Western scientists working on this problem first became aware of the fact that the invasive scourge of our estuaries is also a delicacy in Europe, called moleche.
“It’s a fishery that represents the Lagoon of Venice, you know,” explains Paolo Tagliapietra, the crabber that took Marissa and Jonathan under his wing. “There’s nothing more Venetian.”
Marissa and another lobsterman from Maine spent a week in Venice last year. They stayed in Paolo’s family’s guest house and shared meals with them. Every day they would wake up early, and head out onto the Venetian Lagoon in an open skiff to haul in fyke nets. After three or four hours they would have 800 pounds of green crab, which they would sort through after lunch. (A long Italian lunch, complete with prosecco.)
This is where science has not caught up to tradition. When Gabby Brandt tried to take many high definition photos of around fifty crabs, she couldn’t detect any sign that distinguished the ones that were about to molt from the others. Meanwhile, Marissa says Paolo and his father were sorting at “supersonic speed.”
“They’ll dump like 100 pounds at a time on the sorting table and they don't even need to look at the crabs,” she says, “They're so good that they don't really even... they don't even need to really look at the crab they just see it in the pile of other crabs and it's different to them somehow and they just pull it out and throw it aside.”
I tell Marissa that it sounds like wizardry, but she insists it's just a matter of knowing what to look for and lots of practice. The Italians taught her that the pre-molt crabs have very faint rings around their belly scales… that their rear ends start to inflate as their shell spreads and water gets inside… that they become dramatically weaker as they get closer to a molt.
“And it's interesting too because there was even disagreement amongst Paolo and his father and his brother in law,” she says, “It's sort of like a gut feeling almost. Like we can't rely on that in science, right? So I think that's part of the reason why you know there hasn't really been any major scientific breakthroughs on that front.”
Limits of Science
You might have thought you were signing on for a story about delicious soft-shell crab po’ boys, the truth is this is a story about the limits of science. While I am a big fan of the scientific method, but science has some big blind spots. For instance, the fact that scientists mostly hang out with other scientists and not, say, Mediterranean crabbers.
Centuries old, traditional ways of doing things are often the results of generations of experimentation. How did the first Venetian crabbers figure out which green crabs were about to molt? I can only speculate, but I can tell you it wasn’t with high resolution cameras and computer analysis. They must have had to catch a lot of them; hold on to a lot of them; watch them carefully every day; turn them over and over in their hands; fishing season after fishing season. Hundreds of observers without phones or television to distract them spending years on the water, observing hundreds of thousands of crabs. Then they showed their children, who showed their children.
How could a few people in lab compete with centuries of data like that?
One can take this idea too far — I’m not going to argue the old ways are always better. But I think it’s pretty fair to say, and science has begun to recognize, that there are vast stores of discoveries that we could tap into if science started to take a closer look at traditions and ancient skills.
Green Crabs Come to Market
Paolo has created an 11-page guide to crab molting, but even he says you really can’t learn except by sorting crabs side-by-side with an expert. When you add in the fact that the crabs on our shores appear to be a slightly different sub-species, that is now hybridizing with the Icelandic green crab, it makes it very hard to learn this skill from a book. Which is all to say that for this to work in New England, somehow this particular skill will have to make its way across the Atlantic.
It may have already begun. In New Hampshire, one fisherman has built a side-business of selling green crabs as bait to sport anglers trying to catch tautogs. In Maine, two fishermen have begun to sell soft-shell crabs to restaurants in the MidCoast region: Jonathan Taggart, and a lobsterman who went to Venice with Marissa and Paolo, Chris Jameson.
Chris says he thinks he had to sort through about 20,000 pounds of crabs before he could “really start to focus in on what’s good and what’s not.”
The day I met him, Chris had about 30 crabs that he had identified as pre-molt, and that had shed their shell once he separated them into their individual crab condos. He took those soft-shells to a high-end restaurant later that day. He texted me after meeting with the chef, and told me the crabs sold for $30 a pound. They told him to bring more as soon as he had them.
Outside/In was produced this week by:
Sam Evans-Brown and Logan Shannon, with help from Hannah McCarthy, Justine Paradis, Taylor Quimby, Nick Capodice, and Jimmy Gutierrez. Erika Janik is our Executive Producer. Maureen McMurray is the director of excellent nature puns.
Special thanks to Luke Porrier, Dwight Souther, Jonathan Taggart, and the Gulf of Maine Research Institute.
Music in this episode by Ari De Niro, Podington Bear and Blue Dot Sessions.
Our theme Music is by Breakmaster Cylinder.
Outside/In is a production of New Hampshire Public Radio.