Peconic Bay Scallop Die-Off Due To Global Warming, Heat Waves: Study

EAST END, NY — A new study indicates what many have long feared: The die-off of the beloved Peconic Bay scallops in local waters is likely caused by warming waters and heat waves.

The study, commenced by Stony Brook University researchers and published in Global Change Biology, indicated that global warming has contributed to the loss of bay scallops.

As climate change intensifies, heat waves are becoming more and more common across the globe. In the face of such repeated events, animals will acclimate, migrate, or perish, experts said.

Since 2019, consecutive summer mass die-offs of bay scallops in the Peconic Estuary on Long Island have led to the collapse of the bay scallop fishery in New York and the declaration of a federal fishery disaster, with landings down more than 99 percent, Stony Brook University researchers said.

This study, led by Stony Brook School of Marine and Atmospheric Sciences graduate Stephen Tomasetti, PhD, and Stony Brook University Endowed Chair of Coastal Ecology and Conservation, Christopher Gobler, PhD, as well as a collaborative team of researchers, revealed that extreme summer temperatures, becoming more frequent under climate change, had exacerbated the vulnerability of bay scallops to environmental stress and has played a role in the recurrent population crashes, researchers said.

The study even reported the mass die-off of all scallops at a New York site in 2020, when an eight day summer heatwave event coincided with repeated episodes of low oxygen.

Scallops at locations with higher oxygen or lower temperatures survived, however, researchers noted.

Additional research that year confirmed that the combination of high temperatures and low oxygen reduced feeding and energy reserves, causing mortality in ecosystem and laboratory scenarios, experts said.

"Global warming is happening at an uneven pace in space and time. It just so happens that summer water temperatures in the Northeast are increasing at a rate more than 3X the global average, leaving organisms adapted to cooler temperatures endangered," Gobler, the senior author on the paper, said.

By using a combination of satellite temperature and long-term environmental records, field and laboratory experiments, and measurements of scallop heartbeat rates in an ecosystem setting because scallops heartbeat rates vary with water temperatures, researchers demonstrated that coastal waters from New York to Massachusetts — home to the nation’s northern bay scallop fisheries — are rapidly warming. Bay scallops have become increasingly susceptible to the combination of high temperatures and impaired water quality, they said.

The bay scallop fishery was formerly one of the largest shellfisheries on the East Coast and has progressively vanished from regions south of New York. With the NY fishery collapsed, the only remaining commercial U.S. fishery is in Massachusetts, researchers said.

And, although Massachusetts waters are still in the safe range for bay scallops, they have warmed at a rate even faster than New York waters and could be threatened in the future, researchers added.

Tomasetti pointed to other examples of heat-induced mass mortality on the East Coast, including the loss of lobsters in Long Island Sound and blue mussels in coastal bays south of Delaware.

"Commercial shellfisheries are a vital part of our blue economy, and shellfish habitats are changing rapidly,” said Tomasetti. “Mitigating further warming by transitioning to clean energy is critical. But while these global efforts are underway, committing to practices that will improve our local water quality like reducing nutrient pollution is also important."

Warmer waters physically hold less oxygen, so increasing the baseline oxygen levels in the estuary by improving water quality will help offset future oxygen loss from increased temperature, researchers added.

The authors also warned that warming in the Northeast United States was projected to continue at a faster pace than the global average. The populations of mobile species such as fish can respond by moving to waters with more tolerable temperatures. But for populations of bay scallops and other economically important shellfish species, movement is limited by their ability to disperse through spawning and the availability of suitable habitat. Populations forced to cope with temperature extremes may be more vulnerable to mass mortality events, they said.

For years, local officials have reflected on the disastrous impact of the die-off on the local economy and on livelihoods.

"On eastern Long Island, our environment is our economy. The scallop crop industry can only thrive with resources like clean water and efforts to combat climate change," New York State Assemblyman Fred Thiele said. "With the climate crisis already at our doorstep, we have seen the devastating impact climate change has on our fishing industry. The repeated threat of scallop die-off in recent years due to rising temperatures in our Northeast waters has become crippling to the commercial fishing community and all related East End industries and businesses; this is yet another example of climate change's extreme and adverse impacts across our region."

Thiele said that in addition to the Climate Leadership and Community Protection Act that he helped pass in 2019, the 2022 to 2023 state budget provided "significant investments" to help advance environmental conservation efforts to address climate change, measures he said he believed were a step in the right direction and would have a positive impact "on thwarting the clear and present danger to the fishing industry on the East End."

"We have been watching with dismay the collapse of our unique Peconic Bay scallop population. This research is crucial to not only helping our community restore a vital part of our economy for local baymen and consumers, but will help develop a critically important understanding of how we can address climate change impacts to our environment and marine life," Suffolk County Legislator Bridget Fleming said.

And, added Suffolk County Legislator Al Krupski: "Although the decline in scallop populations is dramatic, I am gratified that the marine science community, which includes so many dedicated individuals and instituions, has pulled together to try to reestablish a sustainable scallop population."

On the opening day of Peconic Bay scallop season this year, purveyors once again lamented the lackluster yield.

Charlie Manwaring, owner of Southold Fish Market, told Patch that baymen had only brought in about two bushels on the first day; others only received less than 20 pounds.

Manwaring, however, said he believes the yield might be a bit better during the winter months, when baymen who are currently out on the water seeking other types of fish turn their attention to the scallops, which promise less of a yield than in years' past.

Keith Reda, general manager at Braun Seafood Market Co. in Cutchogue, told Patch that the pickings were "slim" on the first day of the season. Whatever baymen had brought in was already sold by Tuesday morning, he said.

There were some Peconic Bay scallops to be found, and the baymen that did go out were able to "pick away at a little," Reda said — but they didn't bring home anywhere near the 10 bushel limit, he said. "At least they can go out and get a day's pay," he said.

On the first day, the scallops were priced at $39 per pound at Braun's, he said. "I can't see that going down," Reda said, noting that scallops from Nantucket and Cape Cod are even more pricey.

Those waiting for their first taste of the season were disappointed once again last year when few scallops were available; as the winter wore on, baymen began bringing them in, but the prices were high.

For the past years, fishermen and seafood shop owners alike have dubbed the grim situation "a wash."