There has been a lot of hand-wringing over whether the rampant shell disease afflicting the southern New England lobsters has begun to inch its way north to the colder waters of Cape Ann and the rest of the Gulf of Maine.
Pish-posh, say the scientists and local lobstermen.
“It’s really much ado about nothing up in Gloucester and around Cape Ann,” said Bob Glenn, the New Bedford-based chief marine fisheries biologist for the state’s Division of Marine Fisheries. “We’ve had high incidences of shell disease south of Cape Cod since the late ‘90s. That’s really where the problem is, down in southern New England waters where it’s much warmer.”
Glenn said that, on average, as many as 22 percent of the lobsters harvested out of the warmer New England waters south of Cape Cod have contracted the bacteria-induced epizootic shell disease that, at worse, wholly erodes their shells or, at best, leaves their shells covered with unsightly lesions.
“Up around Gloucester, it’s much less, usually 1 percent or less of the lobsters landed,” Glenn said. “The highest we ever saw up there was 3.1 percent in 2003 and 2.2 percent in 2012.”
That’s good news not only for Gloucester lobstermen, but for lobster lovers throughout the region.
That’s because Gloucester, according to the Massachusetts Lobstermen’s Association, is home to more lobstermen (145) and more lobsters landed (2.27 million pounds in 2011) than any other of the Bay State’s 52 ports.
Frank Ciaramitaro, a co-owner of Gloucester’s Capt. Joe & Sons, and Gloucester lobsterman Arthur “Sooky” Sawyer said their practical experience mirrors the statistical evidence provided by Glenn.
“You might see one or two, but there are no alarms going off up here,” Sawyer said.
Ciaramitaro said he believes there are fewer incidences of the disease showing up in lobsters from the waters around Gloucester and Cape Ann than in years past.
“Taking in 5,000 or 6,000 pounds of lobsters a day, we might see enough (lobsters afflicted with the shell disease) to count on one hand,” Ciaramitaro said. “If anything, it’s going the other way.”
The shell disease, according to scientists, is linked to the same bacteria that eats the shells of lobsters and other crustaceans after molting.
The disease is not contagious, so one lobster cannot transmit it to another. While the meat of the afflicted lobsters remains edible, the shells can appear ravaged and unappetizing enough to render the lobsters unfit for sale in restaurants or retail stores.
Scientists still aren’t sure why some lobsters fall prey to the disease while others avoid it, though evidence appears to be growing that it may have something to do with water temperatures and the lobsters’ growth cycle to full sexual maturity.
“The outbreak of shell disease that we’ve seen in southern New England since the late ‘90s has corresponded with an unprecedented number of days when the water temperature exceeds 20 degrees Celsius, which is about 68 degrees Fahrenheit,” Glenn said.
“That prolonged exposure (to warmer waters) seems to be correlated to the outbreak of shell disease.”
In general, Glenn said, lobsters who grow up in a warmer environment reach sexual maturity at a smaller size and a younger age
Once female lobsters reach sexual maturity, they switch over to a every-other year molting process, which seems to make them more susceptible to the shell disease.
“Typically, those lobsters have the highest incidence of shell disease,” Glenn said.
Glenn said most of the lobsters caught off Cape Ann have not reached full sexual maturity and therefore molt every year.
“Because of that, we see little shell disease up there,” Glenn said.
Sean Horgan may be contacted at 978-283-7000 x3464, or email@example.com. Follow him on Twitter at @SeanGDT