Are lobsters the new symbol of climate change?
The answer, increasingly, is yes. Lobster populations are exploding in the Gulf of Maine, but are plummeting in the waters of southern New England. In 2012, the Gulf of Maine set a record catch of 126 million pounds, double the average of a decade before and six times the average of the 1980s.
Meanwhile, annual lobster landings in Buzzards Bay were just 72,000 pounds last year, down from 400,000 pounds in the late 1990s and from just under a million pounds in the 1980s, according to Massachusetts state lobster biologist Bob Glenn.
The population loss is likely due to warmer waters and disease that may be associated with such water. “We just watched a geological event occur in about a decade,” Glenn said. Scientists speculate that the population boom in Maine is also due to record warm waters, which fueled massive early productions, as well as the overfishing of ground fish that eat lobsters.
The lobster catch in Maine had a record value of $340 million. But the bounty backfired for many individual lobstermen, who were stuck with the lowest per-pound prices in nearly 20 years.
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Further adding to the uncertainty is new research published last month in the journal Science that found that American lobster as a species has shifted 43 miles northward in the last decade. These unprecedented shifts concerned researchers at a Gulf of Maine research conference this week in Portsmouth, N.H.
“Many years ago, Casco Bay used to be a hotspot for lobster. Now it’s more like Stonington and other ports Downeast,” said Suzanne Arnold, marine scientist at the Island Institute. “The Maine lobster is one of the best-managed fisheries and is still in abundance, but the epicenter of that abundance is changing, and many fishermen are now solely reliant on lobster. This northward shift and its speed has me scared for communities where lobster is their lifeblood.”
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As for southern New England, Glenn said conditions were as if “someone flipped a switch.” It used to be that lobsters enjoyed their preferred bottom water temperatures of 54 to 66 degrees for 11 months out of the year. But for much of the last decade and a half, bottom temperatures have been 68 degrees or above for nearly three months a year, which may result in lobsters hatching eggs farther out at sea where the young have much less protection.
In Maine, despite the current abundance of lobsters, scientists fear other switches are in danger of being flipped.
The cutting of coastal rockweed for fertilizer, animal feed, and nutritional supplements has doubled in the last six years, to 15 million pounds, depleting an important habitat for young lobsters.
The state is currently debating regulations to assure a “sustainable” harvest of rockweed, but Cornell University biologist Robin Hadlock Seeley said it is difficult to define “sustainable,” since research is beginning to show that lobsters feed at night in rockweed.
In addition, juvenile lobsters may face new threats from new predators coming north with warmer waters, such as black sea bass.
Other research is showing a significant decline in eggs in lobster females in the Bay of Fundy. Heather Koopman of the Grand Manan Whale and Seabird Research Station said she does not yet know what that means for a creature that can produce tens of thousands of eggs, but she is worried that in “a species that needs just the right mix of cold and warm water for spawning, hatching, growth, and molting, it is hard to see what piece of the puzzle is most important.”
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Until the puzzle is pieced together, the lobster is in danger. For now the waters of Maine are Eden. But Buzzards Bay is nearly an underwater desert.
Derrick Z. Jackson can be reached at jackson@globe.com.