Stephen Tettelbach, a shellfish ecologist at Cornell Cooperative Extension of...

Stephen Tettelbach, a shellfish ecologist at Cornell Cooperative Extension of Suffolk County holds three- month- old scallops and talks about another Peconic Bay scallop die off at CCE’s Suffolk County Marine Environmental Learning Center at Cedar Beach in Southold on Saturday, Oct. 31, 2020. Credit: Randee Daddona

Peconic Bay scallops are experiencing their fourth straight year of a massive die-off this fall, with "concerningly" low numbers of juveniles on top of another year of record-low adults, marine biologists said Thursday. 

Recent surveys by the Cornell Cooperative Extension's Marine Program found a total of only 19 adult scallops at 21 sites from Flanders to Orient Point, with some showing no adult scallops at all, said Harrison Tobi, a marine biologist who specializes in bay scallop aquaculture and restoration.

"It's a pretty bleak outlook for this year's commercial harvest or even the recreational harvest," said Tobi, of the season that starts Monday and continues into March. 

The numbers come after Cornell surveys, funded by Suffolk County, had found a relative resurgence of juvenile scallops in the fall of 2021 and this past spring, Tobi said, with hopes that the overall population might rebound this fall. Newsday reported some bay scallopers had even seen an unexpected uptick in the mollusks as the season came to a close this past winter. 

"We saw high juvenile densities last fall, and we saw high numbers of juveniles in the spring," Tobi said. "Then all of a sudden the adult scallops were basically gone" by mid-July. 

Cornell suspects a combination of a known parasite that preys on the scallops and continuing warm waters are among the primary factors for the die-off. Stony Brook University, which is working closely with Cornell to study the parasite impacts and identify and propagate resistant strains of scallops, has found high levels of the parasite in sample scallops, Tobi said. 

A relative dearth of juvenile scallops in surveys this year is unusual even amid die-off years, and are "concerningly low," Tobi said, because it could lead to even lower numbers next year. Recent surveys concluded in the last two weeks of October. 

Cornell, working with a grant from the Moore Charitable Foundation, is hatching millions of scallops at its facilities to determine which genetic strains may be most resilient in warming waters and other factors that could cause the die-off. 

"Elevated water temperatures and the parasite appear to be what's causing these die-offs," Tobi said. "We're still trying to figure out exactly what factors associated with the elevated water temperatures are causing the factors" that lead to die-offs. 

"Water temperatures are staying warm a little longer and it's causing extra stress for the scallops," he said. 

Tobi said he's hopeful biologists will find definitive answers. 

"We're putting our best foot forward and I'm really hopeful these genetic studies will get us to a stock that helps provide resistance to the parasite and environmental factors," he said. "We're not just going to stop trying. Peconic Bay scallops are iconic. The scallop shell is on everything. You don't just give up on something like that because the outlook looks grim."