About 2½ hours after launching his small boat in the Niantic River Thursday, Lewis Bull returned to the state boat launch in Waterford with a bucketful of oysters, a dozen or so quahogs and just four scallops.

While the scallop haul was scant compared to the clams and oysters he'd harvested, Bull wasn't disappointed. Throughout this winter, Bull, an East Lyme resident and former commercial lobsterman, had enjoyed one of the best years for recreational scalloping anyone can remember, thanks to an abundant population and mild weather that made it possible to make the most of the season that runs from mid-November to mid-March.

"We had so much nice weather, everyone was able to go out scalloping, so they're kind of picked over now," said Bull, whose outerwear consisted of high rubber boots, a zippered sweatshirt and knit cap, clothing seemingly more suited to a brisk fall day than mid-February.

The warm temperatures have left the entire Niantic River ice-free, keeping shellfish beds in the upper river accessible, said John Wadsworth, shellfish warden for the Waterford-East Lyme Shellfish commission.

"There were two of us out just a few days ago and we got half a bushel of scallops," he said. "It was about 42 degrees."

This winter, average temperatures on land have been about six degrees higher than normal, with fewer days falling below freezing and little snow or ice, according to the National Weather Service.

"I've been riding my bike to work all winter," said Maggie Jones, executive director of the Denison Pequotsepos Nature Center in Mystic.

Other than a flock of American coots on the Mystic River that normally would winter farther south, the warm weather hasn't had a noticeable effect on most plants and animals, Jones said. They tend to respond more to changes in day length than temperature. Humans, however, are another story; she's noticed people getting outdoors more this winter, sometimes in shorts and T-shirts.

"The mild winter has probably been changing human habits more than anything," Jones said. "Humans have the most immediate reaction."

Some of the most dramatic effects of the warm winter are being seen on Long Island Sound, where water temperatures are nearly 10 degrees above what's normal for this time of year.

According to James O'Donnell, professor of marine sciences at the Avery Point campus of the University of Connecticut in Groton, water temperatures in the Sound during January and February this year are some of the highest in 60 years. Data he's collected from a climate buoy in the central Sound show the average water temperature in January was about 44 degrees, and about 41 degrees thus far in February. That compares to the 60-year average for those months of about 36 degrees and 35 degrees, respectively.

"There was one day in January when the water temperature was 48 degrees, and the fishing was like 42nd Street and Broadway," said Claire Glas, owner of the Hel-Cat II party fishing boat, which is docked in Groton and runs trips once a week in the winter. "We were catching anything and everything."

Migratory fish species - including striped bass, black sea bass, bluefish and some of the smaller species they feed on - stayed in local waters longer into the winter this year, according to Penny Howell, fisheries biologist at the state Department of Energy and Environmental Protection's marine fisheries headquarters in Old Lyme. Because there were still bluefish in the Sound, DEEP opened the commercial fishing season for bluefish on Jan. 31 this year, Howell said. It usually opens April 15.

For scientists who work in local waters, the mild winter has been conducive to keeping their research on a timely schedule. A team from the Millstone Environmental Lab at Millstone Power Station in Waterford began collecting samples in the upper Niantic River this week, said Don Landers, supervisor of the lab. In some years, that part of the river stays frozen until mid-March, forcing the team to wait until then to begin its annual sampling for adult winter flounder and winter flounder larvae.

Teams from the Millstone lab sample other areas around the nuclear power plant all year long, he said, including Niantic Bay, Jordan Cove and the lower Niantic River. These areas tend to remain ice-free even in the coldest years.

"But," Landers said, "we certainly didn't have to put on all the clothing we normally have to at this time of year."

j.benson@theday.com