Peconic Bay Scallops a Bust, Again

After two deadly years for the Peconic Bay’s bay scallop population, there wasn’t much hope for this year’s scallop season, which opens Nov. 1. 

The pessimism has been borne out.

“By the end of August, the mortality was almost 100 percents in all the sites we monitor, really from one end of the bay to the other,” said Dr. Stephen Tettelbach, a Long Island University ecology professor who heads Cornell Cooperative Extension’s Peconic Bay Scallop Restoration Program. “The more data we’ve collected, everything backs up what we’ve been saying all along, that higher water temperatures, along with this parasitic disease, in conjunction with the spawning of scallops, is responsible.”

As recently as 2018, Peconic Bay scallops seemed on the rebound in a decades-long effort to recover from a devastating series of brown tide algae blooms in the 1980s. But by the time the the November 2019 scallop season began, something was terribly wrong. Sometime between the shellfish’s spawning in late spring and the opening of the season, most of the adult scallops in the bays had died. And the 2020 season proved to be a repeat of 2019. 

But each year, there was a glimmer of hope — even though most of the adult scallops had died, they had somehow managed to produce a plethora of juvenile scallops that seemed to not be affected by whatever was killing the adults.

Peconic Bay scallops live just two years, and it is only legal to harvest them in their second year of life.

“The adults are the ones that are dying and there are large numbers of juveniles. The most obvious difference between these two year-classes is the adults are spawning,” said Dr. Tettelbach.

He and other scientists theorize that, because spawning is such a stressful time in an adult scallop’s life, high water temperatures at the time of spawning, combined with a parasitic infection, made it difficult for the shellfish to survive the stress of spawning.

“We believe the mortality is happening soon after spawning, or maybe even coincident with it,” said Dr. Tettelbach. “We haven’t gotten all of our data downloaded from our loggers, but that’s what we believe.”

With research funding from Suffolk County through Cornell Cooperative Extension, along with help from the lab of Stony Brook pathologist Dr. Bassem Allam, scallop researchers are now working to selectively breed strains of Peconic Bay scallops that have proved resilient against higher temperatures and parasitic infections.

“Next year will be a big expansion on this work,” said Dr. Tettelbach. “We’re hoping to develop a line of scallops that we can use as brood stock for our restoration work going forward…. It’s been done successfully with oysters and clams, breeding for resistance to disease.”

Peconic Bay scallops are a uniquely fragile species, in part due to their short lifespan. Dr. Tettelbach said he’s heard this may be due to a shorter section of a chromosome than other species of scallops.

“There are very closely related species, in the same genus, in Chile and Peru that live to ten years old. That’s a big difference from our guys here,” he said. “People have suggested hybridizing our scallops with scallops from North Carolina or Florida, but I’m not there yet. There are so many things that can and have gone wrong when you transplant wild animals into new areas.”