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.
The last time anybody counted, in 2001, there were about 100,000 harbor seals, and 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 count.
“There’s a 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 Canada 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 counts in 1981, 1986, 1993, 1997, and 2001. The surveys take place during pupping season in the spring, when nearly all the seals are in Maine.
Surveyors take aerial photographs of hundreds of islands and ledges from New Hampshire to Canada and then count the seals that appear in the images. 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 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 since the 1972 passage of the federal Marine Mammal Protection Act. But at one time, they were considered nuisances.
Beginning in colonial times, New England communities enacted intermittent bounty programs to control the seal population. Massachusetts had a seal bounty program until 1962.