Baymen Question Potential Causes of Scallop Die-Offs

In the six years since the devastating annual die-off of Peconic Bay scallops began, researchers have begun homing in on lack of genetic diversity in the local scallop population as a driving factor. 

The genetically weak strain of scallops that have been used to repopulate the Peconics since die-offs in the 20th Century appears to be far less resistant to a parasite, Bay scallop microsporidia, than scallops in nearby water bodies.

But baymen who turned out in force for a Dec. 18 forum with scallop researchers at the Cutchogue-New Suffolk Library asked the scientists to expand their research, looking at agricultural chemicals, potential cross-over from other farmed shellfish species and warm winters that prematurely “age” the scallops as potential causes.

Warming water temperatures, particularly at the time the scallops spawn in late spring, have been considered to play a factor in the die-offs, which have continued in the same pattern since their inception in 2019.

Scallops, which live for just two years, usually spawn as they reach maturity at the end of their first year of life. But after they spawn, these adult scallops have been dying, year after year, before they reach the season in which they can be harvested, which begins in November.

The silver lining on the way they’ve been dying is that they do spawn before they succumb to the parasite, leaving their offspring to grow for another year before facing the same fate.

Researchers at Cornell Cooperative Extension’s Peconic Bay Scallop Restoration Program, based in Southold, have been working with Stony Brook shellfish pathologist Bassem Allam, who found the parasite to be prevalent in dead scallop tissue, particularly in its kidneys.

But Dr. Allam, who named the parasite, said at the Cutchogue forum that he’s since seen a 1984 scientific paper documenting a similar parasite “on the East Coast between New York and Massachusetts, under stressful conditions.”

He said the images taken through a microscope of the parasite appear similar to the most recent outbreak — although there’s no way to tell how genetically similar they are based solely on the images.

“Did anybody figure out where this parasite came from yet? It seemed to come out of thin air,” questioned Nate Andruski, president of the Southold Town Baymen’s Association. “It seems like it could be introduced by cultured oysters — these oysters are coming from other places, and with this oyster farming fad that’s going on, this parasite couldn’t come from the oysters? That’s impossible?”

“We believe the parasite has been there for quite some time, under the radar screen,” sid Dr. Allam, adding that scallops have been found in the laboratory to have more difficulty fighting off the parasites when the water temperature is higher.

“They are highly specific,” he added, saying it’s unlikely the parasites came from another species. “They live inside of the host cell for a good chunk of their life, and there is some specificity to their host match.”

Aquaculture Specialist Harrison Tobi, who has been leading scallop research at Cornell Cooperative Extension’s Southold marine station since the retirement of Dr. Stephen Tettelbach, said the lab has “tested a whole bunch of shellfish — whelk, oysters, and even pea crabs that live inside of scallops — but the only species this parasite infects is scallops.”

Tim Winters of Cutchogue, who grew up scalloping in Hallocks Bay in Orient, said he remembered as an eight-year-old kid working “all morning at the culling boards. It got me out of school and my pay was a pack of Pokemon cards.”

But that doesn’t happen anymore. This scallop season started out with such a grim forecast that most longtime baymen didn’t even try to go out opening day.

Mr. Winters asked the researchers to look into a potential link between the die-offs and agricultural chemicals.

Dr. Tettelbach, who was on the panel, had given an overview of the boom and bust history of the Peconic Bay scallop, documenting a die-off in the 1930s, and the concurrent struggles of eelgrass beds in the Peconics, which provide vital habitat for young scallops.

“Was there anything at that time with potato farming, fertilizers being put in the ground, and stormwater runoff into bays killing eelgrass?” asked Mr. Winters, adding that in the 1950s there were only 400 pesticides that could be used on crops, but there are more than 10,000 available today.

 “I’m not against farms. It’s so important to have local food. But there has to be a balance,” he said. “There’s no set of clams out here, no set of steamers. It’s not just the scallops.

His father, Pete Winters, had similar questions. 

“The eelgrass die-off is when the vineyards exploded in New York. I don’t know if it’s a correlation or not, but it’s awful ironic. The eelgrass died. The vineyards took off, the nurseries took off, and the sod farms took off.”

He added that he’d once gone out to work on Hallock’s Bay after a big rain and “my eyes were burning from the runoff. The water was milky.”

“We’re not going to beat the vineyards. We know that. But maybe alternative pesticides could be used,” he said.

Dr. Tettelbach said he wasn’t prepared to throw any industry under the bus, “but we totally hear you.”

He added that water temperature has also been a big issue with eelgrass.

“There hasn’t been eelgrass west of Shelter Island, except for Bullhead Bay, since the 1970s, maybe the 1950s,” he said. “Cornell stopped doing eelgrass restoration in the western bays, because it just didn’t survive. That is part of the story as well.”

He said researchers are currently working to find other, more heat-tolerant macroalgae that young scallops could attach to.

Mr. Tobi added that Cornell is also trying to find heat-tolerant strains of eelgrass that could be grown in the Peconics.

Panelist Stephen Heck, a marine ecologist, has studied scallop habitat both here and in Nantucket, where scallops have been found to have the parasite but still survive. 

“Making comparisons between the different systems is important, from a genetic standpoint,” he said. 

He added that experiments done in tanks have shown that glyphosate, the chemical in Roundup, has been shown to wipe out eelgrass populations at very low concentrations.

“It’s pretty hard to monitor the concentration of those things in nature, but it certainly doesn’t bode well,” he said.

Matt Ketcham, owner of Peconic Gold Oysters, an oyster farm in the Peconics, said he’s continued to find thriving scallops in his oyster cages throughout the die-off.

“Something about being in cages may be changing their spawning habits and life cycle somehow,” he said. 

He added that, in the first year of the die-off he caught some surviving scallops and sent them to Rutgers University to be spawned, hoping to try to grow them out in his gear, but didn’t receive approval for the project from the New York State Department of Environmental Conservation.

“We’ve had some really hot summers, and had great scalloping, but we also had deep freezes in the winter. That’ ain’t happening this year,” he said. “Maybe those mild winters are aging the scallops more, so an 18-month-old scallop is more like a two-year old scallop.”

He said that phenomenon has also been observed in oysters that succumb to the parasite that causes dermo, an oyster-specific disease.

Charlie Manwaring, owner of the Southold Fish Market, echoed that sentiment

“I think they’re dying because they’re too old,” he said. “The last four to five years, they grow beautifully and then in August and September, we get a big kill-off.”

“They’re dying before they should,” countered Dr. Tettelbach. “Most are dying in July and August. They aren’t living to anywhere near harvest in November.

But the elder Mr. Winters said he’s seeing something unusual — scallop that still have spawn inside them in December.

“We’ve seen a lot of animals still ripe in October and November, but December is unusual,” said Dr. Tettelbach. “But it’s warmer now than it used to be. That is an important phenomena historically.”

He added that the most important work being done now, from the fishery’s perspective, is to buffer the population by introducing resilient local scallop populations, from areas like Moriches Bay, into the Peconics.

“It’s called stock enhancement,” said Mr. Tobi, adding that this has been done in many other shellfish fishers. “If we spawn 100 scallops, they produce 400,000 scallops, and they will enter our spawner sanctuary (in Orient) and spawn. Four hundred thousand is going to produce a lot of scallops in the wild, and create a more disease-tolerant population in the Peconics.

“It’s an iconic species. It’s very important to us all, and that’s what’s driving all this work,” he added.