Groundhog Day for Bay Scallops?

Pictured Above: Aquaculturist Karen Rivara of Southold is working with Dr. Tettelbach to keep resilient Peconic Bay scallop broodstock alive.

This coming Peconic Bay scallop season could prove a repeat of last year’s devastating die-off, says Dr. Stephen Tettelbach, a Long Island University ecology professor who heads Cornell Cooperative Extension’s Peconic Bay Scallop Restoration Program.

In addition to the recurring warm water temperatures that thwarted last year’s scallops, the shellfish faced two additional threats this year, says Dr. Tettelbach — the more widespread presence of the cownose ray, a southern species that had destroyed shellfish beds throughout the Chesapeake Bay and is just now beginning to get comfortable in Long Island’s warming waters, and the return of the rust tide Cochlodinium, which can be toxic to shellfish but hadn’t been seen in the Peconics in 2019.

“I really feel that we’re seeing firsthand the effects of the climate crisis here,” said Dr. Tettelbach, who added that warming waters that contain less oxygen are a telltale of the climate’s influence on the system. “We’re working to try to really nail down exactly whats going on out there, and take some steps to try to address that.”

The Peconic Bay scallop season begins the first Monday in November and continues through March 31, 2021.

When the Scallop Research Project’s researchers did their 2019 spring surveys of about 20 major scallop sites throughout the bays, they were heartened by the large numbers of scallops they found. But by the time last year’s season began in November, baymen were pulling up empty shells, or worse, nothing, in their dredges. 

Dr. Tettelbach’s team initially thought high water temperatures and low dissolved oxygen at the time the scallops were spawning stressed the shellfish enough to kill them. A parasite was later found to be a partial culprit. 

But there were massive numbers of baby scallops last year, too small to harvest, throughout the bays, giving credence to the theory that the adults had spawned before they died, and also giving hope for this year.

Dr. Tettelbach’s team, which usually surveys sites in the spring and again in the fall, did mid-summer surveys this year of three normally productive scallop grounds, two in Orient, and one in Northwest Harbor (in East Hampton), in the hopes of better pinpointing the timing of a potential die-off.

“In our spring surveys in May and June, there were areas that had pretty good densities of scallops. We were encouraged. But at the beginning of August, we saw very, very heavy mortality of adults at all three sites,” said Dr. Tettelbach. “We know there was about 50 percent mortality by late July.”

The cownose ray and rust tide may also have impacted Peconic Bay scallops this summer (photos Wikipedia CC & The Gobler Lab).

All this was before the rust tide and the cownose rays showed up in the Peconics. 

By the end of the first week in August, Dr. Tettelbach began hearing from fishermen friends that the rays had been spotted in Flanders Bay, Noyac Bay, Shinnecock Bay and off of Shelter Island. Last year, the few ray sightings he’d heard of were farther east, near open water.

“I’m not thrilled to hear they’re that far in. The fact that we’re seeing them in Flanders is not wonderful news,” he said. “We don’t know that much about these rays — how many there are, where they are going, and when they are going to leave, if they haven’t left already.”

While the New York State Department of Environmental Conservation considers cownose rays to be an integral part of New York’s marine food chain, the agency did survey fixed gear commercial fishermen in response to last year’s scallop die-off, to determine the quantity and timing of cownose ray bycatch in their gear.

“Preliminary results indicate the majority of commercial fishermen did not observe a change in the occurrence of cownose ray as by-catch compared to past years,” according to the DEC, but “commercial fishermen that did report greater quantity of rays identified the timeframe of late September through October.” 

While the DEC does not consider cownose rays to be an invasive species in New York waters, “water temperature is a contributing factor in their preferred habitat and warming ocean temperature may impact their range,” according to the agency.

The DEC encourages the public to submit reports of unusual marine life to FW.marine@dec.ny.gov.

The Peconic Estuary Partnership has also asked community members to submit observations of schools of cownose rays in the Peconic Bay to info@peconicestuary.org and include the number of rays, location, date, time, and images, if possible. 

As the rays were arriving in mid-summer, so was an all-too-common algae bloom.

In late July, Dr. Christopher Gobler’s laboratory at Stony Brook Southampton, which focuses on harmful algae blooms, began tracking a widespread ‘rust tide’ throughout the Peconic Estuary.

“What began as an isolated event in Sag Harbor last week has spread across the entire Peconic Estuary from Riverhead to East Hampton and into eastern Shinnecock Bay,” reported the Gobler lab on July 29. “Recent rust tides on Long Island have resulted in massive kills of fish and shellfish on eastern Long Island. Rust tide is NOT harmful to humans in any way.”

“We have identified climate change and specifically warm summer temperatures as a trigger for these large, widespread rust tides,” said Dr. Gobler at the time.

Dr. Tettelbach said he hasn’t seen much research regarding the effect rust tide has on Peconic Bay scallops.

“We know rust tide was around this year. We still don’t have a good read on how much that affects scallop population, but it certainly could,” he said.

Clockwise from top left: Shellfish farmers Katie Marino, Karen Rivara and Melanie Douglass (l-r) at the Shellfisher Preserve, where they are raising resilient scallop bugs; Cornell Cooperative Extension has been working for 15 years to replenish scallops in the Peconic Estuary, with the largest spawner sanctuary in the country in Orient Harbor (CCE Film Still); Dr. Stephen Tettelbach; Four-month-old scallops at the Shellfisher Preserve.

With so many environmental factors working against the Peconic Bay scallop, Dr. Tettelbach is putting together a project with Stony Brook pathologist Dr. Bassem Allam, with the help of Karen Rivara of the Aeros Cultured Oyster Company in Southold, to cultivate scallop broodstock that are resistant to these threats.

It’s natural selection, with the help of some human hands.

Earlier this spring, Dr. Tettlebach brought adult scallops that had survived the die-off in three locations — in Flanders Bay, Southold and Shelter Island — to Ms. Rivara’s nursery at the Peconic Land Trust’s Shellfisher Preserve in Southold.

“We want to see if we can potentially breed a bay scallop that’s resilient to low dissolved oxygen and high temperatures in the summertime,” said Ms. Rivara. “There was also a protozoan parasite infecting the bay scallops last year, and we want to see if we can breed resistance to that.”

The team had been hoping to get funding to begin a research project this year, but “Covid got in the way of that,” said Ms. Rivara, who is hoping grant funding will come through either next year or in 2022.

In the meantime, she spawned the scallops Dr. Tettelbach brought her this spring to try to keep the broodstock lines alive, and is now juggling where to keep all these scallops as they grow. At first she had about a million larvae, and now, four months in and about the size of a nickel, there are still 10,000 scallops in her cages.

“We wanted to get started working on producing something that’s resistant,” she said. “The output from the adult scallops was pretty good, but bay scallops are pretty sensitive to overcrowding. They just require a lot of space. You can grow oysters and hard clams more densely. I have the gear, and I did this as a ‘let’s see what we can do.’ It helps us for planning down the line.”

“We want to try to identify scallops from the natural population that might have greater resistance to disease, low dissolved oxygen and high temperatures — that is a trait that is variable in the population. We would use those going forward as broodstock for Peconic Bay scallops,” said Dr. Tettelbach. “There’s no guarantee that it will get funded, but I certainly see that as a way forward here.”

He added that scallops in the Peconic Bay Scallop Restoration Program’s spawner sanctuary, just of the causeway in Orient’s Hallock Bay, have fared better than scallops in other parts of the bays.

“They’re in nets, protected from predators, in a part of the bay where the water temperatures are a little cooler,” he said. “We’ve seen very good survival in the nets, and that’s a huge part of the spawning population. We hope it will continue.”

Dr. Tettelbach’s team is beginning its fall surveys of scallop sites throughout the Peconics in early October, and they’re expected to share their findings before the start of the season Nov. 2.