As the harvesting season for bay scallops gets underway, Island fishermen and shellfish wholesalers are readying themselves for their annual gamble in a fishery with a reputation for uncertainty.

Known for their distinctive sweet flavor and tender meat, bay scallops have historically been sought after in the culinary world. The Vineyard and Nantucket, among the largest bay scallop fisheries on the east coast, have reaped the benefits.

But large fluctuations in the bivalve’s crop over the years have left market demand inconsistent, and harvesters are anxiously waiting to see what this season brings. 

“I have not heard any predictions so far about this market, but it really changes so much year after year and even throughout the season,” said Emma Green-Beach, executive director of the Martha’s Vineyard Shellfish Group. “Every pond on the Island is a little different and there’s just a lot at play.”

Islandwide, last season’s harvest was exceptionally bountiful, but demand for the scallops waned as the year progressed, leaving fishermen and wholesalers with loads of overstock and nerves about the delicacy’s decreasing popularity. 

“Last year we had the best season we’ve had in at least 12 years,” said Edgartown shellfish constable Rob Morrison. “But there are outliers. And as a trend through the years, the scallop harvest is declining.” 

Commercial and recreational bay scallop season runs from fall to spring, though opening and closing dates vary from town to town. In Chilmark, recreational fishermen are already on the water getting a first glance at what hides beneath the surface. 

While Edgartown had a banner year, Menemsha Pond hit an all-time low last season for its bay scallop harvest, recording only approximately 12 bushels. Shellfish constable Isaiah Scheffer said that he has higher hopes for this season after finding several of the scallops lodged in the pond’s crab traps. But he is not holding his breath for a big scallop comeback. 

“We’ve found quite a few [bay scallops], but they still seem pretty small,” he said. “We have yet to see a big explosion of growth in our adults that there’s been in the past.”

After Nov. 14, when Chilmark’s commercial season opens, Mr. Scheffer said that he will be able to better gauge the health and abundance of the scallops and determine if their smaller-than-usual size is pervasive. 

There have also been early reports of small bay scallops in Sengekontacket Pond and some Edgartown waters, said Ms. Green-Beach. 

“On [recreational] opening day in Edgartown (Oct. 1), I got a text from someone saying, ‘What the heck? They’re so small,’” Ms. Green-Beach said. “And I’ve heard some reports and have seen with my own eyes the low meat yield out of the scallops in Sengekontacket. When [fishermen] shuck them open, they’re just not getting very many pounds or much volume per bushel of scallops. That could impact the price that harvesters get from those bay scallops at market . . . if the meats are smaller sometimes they’re just not worth as much.”

There are several environmental variables that can impact bay scallop growth and numbers from season to season. 

Eelgrass plays a large part in protecting seeds and young scallops. Without it, the bivalves are left exposed to crabs, whelks and other predators. In some ponds, such as Nashaquitsa in Chilmark, nitrogen runoff has caused thick algal blooms that block sunlight from reaching eelgrass. There, scallops are hard to come by. 

Warmer water temperatures can also harm scallops, said Ms. Green-Beach, and any incoming changes to the Island’s aquatic ecosystems from climate change may make their survival even more unpredictable. 

But the newest and most troubling threat to bay scallops is a parasite that decimated populations in New York’s Peconic Bay and was detected in Vineyard and Nantucket waters last winter.

The parasite invades and infects the scallops’ body tissues, including those in the kidney, gill, gonad and abductor muscle. It has yet to hit the Vineyard’s scallop stock as hard as New York’s, but Ms. Green-Beach said that she is working diligently with Bassem Allam, a shellfish researcher at Stony Brook University, to get to the bottom of the mystery disease. 

“[Mr. Allam] is using genetic tools to confirm that, in fact, the parasite that we are seeing here is exactly the same or closely related to the parasite that they’re seeing in [New York],” said Ms. Green-Beach. “Even though there seems to be this parasite all across the Island, we’re not seeing the same dramatic, large-scale mortality that they saw in Peconic Bay.”

Mike Holtham, manager of the Net Result fish market in Vineyard Haven, is also keeping a close eye on the bay scallop market. He sells the shellfish wholesale and usually has consistent customers who distribute them to restaurants and markets in Boston and New York. But by the end of last season, he had to freeze nearly 1,000 pounds of scallops due to lack of market interest.

“I usually count on freezing anywhere between 300 and 500 pounds a year,” he said. “But last season I ended up with so much . . . . We finally worked through them by mid-September but I had to push them more than I normally would.” 

Mr. Holtham said that he is already getting inquiries from some of his regulars about the Island’s scallops, but demand is almost always high early in the season. Once the holidays have passed, the market is anyone’s guess, he said. 

“I’m preparing for the same as last year and am hoping I’m wrong,” he said. “Last year we were seeing people who would normally have consistent 200-pound-a-week orders get one at one time for just a week’s special.”

Longtime scalloper John Conlon, of Edgartown, is not as concerned about the season’s unknowns. A commercial fisherman for 47 years, he has seen the bay scallop crop and market take many turns. Though last year, he admitted, the demand seemed especially low.

“I had numerous days when I just didn’t have a market to sell,” he said. “That’s never happened before. Before, you know, the price might be low but they would still buy them. Last year they were like, no, we can’t even buy them right now.”

Still, Mr. Conlon is always willing to take the gamble. 

“Anything can happen so I honestly have no clue how this year will turn out,” he said. “I haven’t talked to anyone this year and I haven’t looked myself yet. But I’m just going to go out and try no matter what.”