Lobster Shell Disease


By Sean Corcoran

A mysterious disease affecting the shells of lobsters has the fishing industry on edge, and teams of scientists are working to find out what's causing it. The illness doesn't make the lobsters inedible, just unappetizing. This year the numbers of diseased lobsters seems to have declined, further adding to the mystery of what is causing lobster shells to rot away.

About 20,000 pounds of live lobsters pass through the bay doors at Joe's Lobster Mart at the Sandwich Marina each week. That's thousands of kicking crustaceans with butter baths in their futures arriving each day.

With a toss through the air, Scott Thayer separates them by quality and size into large numbered bins, all connected so fresh water from the Cape Cod Canal swirls and flows through them to keep the lobsters fresh.

Scott Thayer: "That's what we're known for on the East Coast -- Maine is known for their lobsters, and the Cape Cod area, a lot of people will come here, and that's their summer vacation and it's a treat, you know? Not like eating chicken. It's a special treat to eat lobster."

Thayer is the foreman and manager of Joe's Lobster Mart, one of the largest lobster retailers on the Cape. But there's a significant number of lobsters -- as much as 30 percent of the entire population in Southern New England -- that Thayer and other resellers won't buy. It's that number, scientists say, that are plagued by a lobster shell disease.

Scott Thayer: "You don't sell them, we don't sell. We don't buy them. We mostly give them back -- our fishermen won't keep 'em. If they see it, it's usually a softer lobster. They're not a good quality lobster. They're not a marketable lobster."

Lobster shell disease doesn't usually affect the meat of the animal -- although it can in the most severe cases. But something -- and scientists don't quite know what -- eats away at the lobster's shell, creating deep holes and making it soft to the touch and unappetizing to the eye.

Scott Thayer: "What a shell disease looks like on a lobster is similar to a vehicle or a bumper that's rusted, almost like a pitted, rusty type appearance on a lobster's outer shell."

Tim Verslycke (VER-SLEK-A) is a postdoctoral investigator at the Woods Hole Oceanographic Institution. He's part of a consortium of scientists called the New England Lobster Research Initiative, who are studying the disease to determine what's behind it, and why it's spreading so quickly.

Tim Verslycke: "Shell disease is something that is common in a lot of crustaceans, and it's been known for a long time. What we are seeing now, we call it epizootic shell disease, it's almost like an epidemic proportion. So we see a lot larger incidences than what you would normally see. We might see 5 percent, 10 percent shell disease in any crustacean population, but we are seeing well over that at this point in lobsters."

So far, scientists are largely baffled as to what's causing the shells to rot away. Why are some lobsters affected and not others? If you put a diseased lobster in a container with a healthy one, it doesn't seem to pass from one to the other. But why is more disease found in Southern New England waters than farther north? Why more in Buzzards Bay than Cape Cod Bay? And, perhaps most importantly, why is it spreading northward to Maine?

Tim Verslycke: "We talk about it as a disease, but it really is not a disease at this point, because we don't know what's causing it. There are certainly microorganisms eating through the shells, people call it shell rot sometimes. You know, if it was really a disease we would be able to tell, this is the microorganism that's causing it. We would be able to take it out, culture it and infect another animal and be able to establish that this organism is causing this disease, but at this point we can't do that."

Backed by federal funding, Versylcke (VER-SLEK-A) says scientists at WHOI and the Marine Biological Laboratory in Woods Hole, as well as at the New England Aquarium and the University of Connecticut, all are looking at different aspects of the disease to see if they can find the cause, and perhaps a cure.

Tim Versylcke: "A lot of times with these things there is a multi-factorial aspect to this, as with any disease. Why are you seeing animals in the exact same space and one is getting sick and the other s are not getting sick? They are in similar environments but something is going on there. So that will be the interesting part to figure out. And what we think is it is probably related to acceptability of certain animals and by looking at that, we are hoping to get some answers."

Rob Connelly has been catching lobsters for 30 years, and he's the skipper of the American Beauty, tied up at the Sandwich Marina. He says he hasn't caught many diseased lobsters this year -- and that's another mystery scientists are trying to work out: Why fewer this year than last? But Connelly says he's glad to know that the scientific community is taking the problem seriously.

"You don't know what else could happen. It might suddenly be, boom, 50, 60 percent of the lobsters getting affected. . . Can't be a bad thing that people are looking into it. Find the problem and maybe fix it. If they can."

Verslycke says the New England Lobster Research Initiative's work should be completed by the spring of 2009. The hope is that answers will be found by then, and that the disease will not spread to even further jeopardize what is one of New England's favorite meals and foremost cultural icons -- the lobster.