Friday, May 24, 2013
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Jeff Runge, professor of oceanography in the School of Marine Sciences at the University of Maine and a researcher at the Gulf of Maine Research Institute, examines plankton samples to test acidity in the ocean. “It’s starting to be recognized as a serious issue. But it’s very complex,” he said.
Gabe Souza/Staff Photographer
Exactly what the changes mean and how they'll play out -- for marine life and the thousands of Mainers who get their livelihoods from the sea -- is not yet clear.
But it is no small matter. In 2012 alone, Maine's fisheries accounted for $521.5 million in revenue, with lobsters bringing in $349 million; soft-shell clams, $15.3 million; scallops, $2.9 million; blue mussels, $1.9 million; cod, $1.6 million; and oysters, $1.45 million, according to the state Department of Marine Resources.
"The clammers in our community (about 50 families) are very concerned about this ... and about losing their livelihoods," said Kristina Egan, vice-chair of the Freeport Town Council, which last year allocated $100,000 for a study of increasing numbers of green crabs overrunning the shellfish flats and eating immature clams.
"We're also concerned about losing this historic industry in Freeport," she said.
Chad Coffin of Freeport, president of the Maine Clammers Association, says he believes ocean acidification is real, but it is not certain how serious it is for clammers or what can be done about it.
"I don't think it's a particularly big issue for the shellfish industry," Coffin said.
But the impact of green crab migration on shellfish beds is an immediate concern, he said.
"We're in big trouble," he said. "Green crabs have already eaten their way through the scallops, urchins, mussels and now clams."
If these aggressive predators are not stopped, he said, they could wipe out the resource and move on to lobsters -- a view shared by Carl Wilson, a marine resource scientist with the state Department of Marine Resources.
Freeport officials say they believe the crabs have proliferated because of at least a decade of relatively warmer winters and ocean temperatures that no longer dip much below 40 degrees -- not cold enough to cause the seasonal die-offs that keep the crab populations in check.
At least that's the theory. But there are still many unanswered questions about ocean acidification's effects on the state's fisheries.
"We are still learning about the details and implications," Wilson said.
"Ocean acidification is going to happen over a long period," he said. "The two (climate change and ocean acidification) are interrelated."
Wilson noted that a century of records from Boothbay Harbor indicate that eight of the 10 warmest summers have occurred in the past decade. Most researchers and observers agree that conditions in the gulf are markedly different than they were even 20 years ago.
LOBSTER HARVEST 'PRECARIOUS'
Many fishermen fear that the changes do not bode well for the species they harvest. Though Maine lobstermen have enjoyed an almost quantum leap in their harvests in recent years, with a record haul in 2012; shellfishermen are struggling, and groundfishermen have watched their fishery virtually dry up.
"This very high abundance of lobster is very precarious," said Wilson. "That's the lesson we learned from southern New England and Cape Cod -- warm water and other factors led to an eventual crash."
The annual lobster harvest has skyrocketed from 20 million pounds to nearly 125 million pounds in the past 25 years, and Wilson said there are no indications that the lobster population is going to collapse. The species is expanding in its northern range, and the distribution of lobsters is increasing east of Penobscot Bay. But populations south of Penobscot Bay may not fare as well, he said.
Wahle, the UMaine marine scientist, noted that ocean conditions in Maine are becoming more like Rhode Island or southern New England.
"That, in itself, is a bad thing," he said.
Rhode Island, New York and Connecticut have seen their lobster fisheries decimated by shell disease, first diagnosed in the 1980s and now linked to warmer water temperatures. The infection damages the exoskeleton with black spots, pits, ulcerations, and sometimes total rot. The disease does not taint the meat but renders the lobsters impossible to sell.
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