PORTLAND, Maine — A century ago, seals were rare along New England’s coast — the victims of fishermen and others who viewed them as fish-gobbling pests that threatened their livelihoods.
But times have changed and the last time anybody counted, in 2001, there were about 100,000 harbor seals. Scientists have begun the first seal census in a decade to determine how many there are now.
Indicators suggest that the population has continued to grow in the past 10 years, said Gordon Waring, who is leading this spring’s seal survey.
“There’s a general consensus that there are a lot of seals around,” said Waring, who heads the seal research program at the Northeast Fisheries Science Center of the National Oceanic and Atmospheric Administration in Woods Hole, Mass.
In the western North Atlantic, harbor seals are found from eastern Canada south to southern New England and New Jersey. The greatest numbers are off the coast of Maine, where they often are seen resting on ledges and outcroppings along the rocky coast.
Scientists conducted their first aerial survey of Maine’s harbor seals in the early 1970s, followed by additional counts in 1981, 1986, 1993, 1997 and 2001. The seal surveys take place during the seal pupping season in the spring when nearly all the seals are in Maine.
To count them, surveyors in an airplane take photographs of hundreds of islands and ledges from New Hampshire to Canada and then count the seals that appear in the photos. They use that base number to estimate the total number.
Before taking to the air, scientists capture a few dozen seals and attach small, temporary radio transmitters to them to help track the animals during the aerial surveys to get a more accurate count. That work began in early April off Cape Cod and continued last week off the coast of Rockland.
The aerial surveys will take place in May and June, with plans to have the photographed seals counted by next fall for an abundance estimate that the scientific team will review.
The seal numbers have been growing for years, gaining momentum since coming under federal protection with the 1972 passage of the Marine Mammal Protection Act. But at one time, they were considered nuisances that were bad for fishermen and the fish that seals like to eat.
Beginning in colonial times, New England communities enacted intermittent bounty programs to control the seal population. Maine offered a $1 bounty on seals until 1905 to reduce their populations to help fish stocks — bounty hunters brought in seal noses to prove their kills. Massachusetts had a seal bounty program until 1962.
In recent years, there seems to have been a shift from western to eastern Maine on where seals give birth to their pups, Waring said. He attributes the shift to increased human activity in western Maine.
Tom Ring, owner and operator of Atlantic Seal Cruises in Freeport, thinks there were more seals in Casco Bay 25 years ago than there are today. The growing numbers of kayakers and other recreational boaters bother seals, he said, forcing them to move to other ledges where there are fewer boats to disturb them.
Still, the population is healthy, he said.
“We see seals about 95 percent of the time, no problem,” he said. “I would say there aren’t as many as 25 years ago when I started, but what I think’s happening is there are more people in small craft out on the water than there were 25 years ago.:”
And the seal’s range appears to be growing, he said. Last winter, while working on a tugboat, he was surprised to see a harbor seal swimming in the waters between New Jersey and Staten Island, N.Y.
While the seal census focuses on harbor seals, there has been a significant increase in the number of gray seals in New England, Waring said. He’s interested in the interaction between the harbor seals and the larger, more aggressive gray seals.
“One of the questions we have is what is the big increase in gray seals doing to harbor seals,” he said. “Are they displacing them from habitat? Are they competing with them?”