NORWALK, Conn. – It’s a sight New Englanders aren’t entirely used to seeing: Thousands of seals swimming through the Long Island Sound or hauling out to Maine, where they like to have their pups.

Seals traditionally have migrated into southern New England waters in the winter. But as their numbers have grown following passage of the Marine Mammal Protection Act of 1972, an increasing number of seals crowded out of Maine and Massachusetts waters have been looking to make southern New England their permanent homes.

There are as many as 100,000 harbor seals in New England waters, yet what is known about these mammals is very little.

Regional experts recently met at The Maritime Aquarium in Norwalk to develop a research plan to explore where exactly the seals are coming from, what food they are eating and what kind of impact the expanding population may have on commercial fisheries.

“My personal sense is you’ve got a lot to learn from the abundant species. It’s important to look at Mother Nature’s success stories,” said Greg Early, a contract biologist based in New Bedford, Mass.

Before the protection act, seals were a dying breed that were once hunted by fishermen who regarded them as their competition. In 1973, there were only 5,800 seals counted in Maine, a number that probably reflects the entire New England population at the time, said Amy Ferland, a harbor seal census researcher for The Maritime Aquarium.

“They were almost completely wiped out,” Ferland said.

It became illegal to hunt or harass seals under the protection law and the population has since recovered, with female seals bearing one pup each year, Ferland said.

In addition to the harbor seals, there are between 5,000 and 7,000 gray seals that usually haul out to Muskeget Island, located between Martha’s Vineyard and Nantucket, in the winter to have their pups.

There also are a number of harp and hooded seals that researchers believe are breeding in Canadian waters and only coming down to New England during certain times of the year, said Gordon Waring, a research fisheries biologist at the National Marine Fisheries Service.

Waring said researchers are interested in exploring any genetic links between harbor seals that are mating in U.S. waters and those that are breeding in New Brunswick and Nova Scotia.

Funding for marine research is expensive; Waring estimates that a complete abundance survey for New England could cost as much as $300,000. The count, which includes the use of two airplanes and radio tagging, is completed over three or five years.

To collect diet information, scientists would need an additional $100,000 to look at seal droppings or to examine the stomachs of stranded, dead seals. A research plan for the group is still in the early stages, but scientists hope to eventually secure a federal grant for funding.

Commercial fishermen in Connecticut who have watched their winter flounder population decline over the last few years say the research is necessary to their livelihood.

Winter flounder is the most sought-after fish by both recreational and commercial fishermen, said Eric Smith, acting director of the state’s Department of Environmental Protection’s marine fisheries division.

“If the research comes to show that we’re never going to get a strong winter flounder stock because seals are knocking the population down to very low levels, then that would be nice to know. I wouldn’t like the idea of it, but at least I would have something to say to these fishermen,” Smith said.

Any talk of implementing a controlled harvest on the seals to keep the growing population in check would be met with such strong resistance that it’s almost entirely unlikely, Smith said.

“It would take an act of God and probably a bit more for me to think that this country would go back to harvesting mammals,” Smith said.

Researchers say the high seal population is bound to have an impact on humans. Boaters and kayakers may be unknowingly breaking buffer zones set in place by the protection act and some seals are actually hauling out onto privately owned waterfront properties.