Gray seals are once again thriving in New England, after their numbers have been decimated for over a century. The animals were hunted in New England until the Marine Mammal Protection Act was passed in 1972.

The seal population has clearly grown in number, but it had been difficult to pinpoint by how much. David W. Johnson, a professor at Duke's Nicholas School of the Environment, said in a statement that past surveys that used traditional counting methods counted about 15,000 seals off the Massachusetts coast.

Technology-aided aerial surveys that used Google Earth imagery in conjunction with telemetry data that tagged animals suggested the numbers to be around 30,000 and 50,000 today. This, according to Professor Johnson, is a "conservation success."

In a research published in BioScience, it is noted that gray seals were counted along the coast of Martha's Vineyard, Nantucket and Cape Cod. The pinnipeds, as they are called, spend a lot of time in the water.

During the aerial surveys made by researchers, the light color of the seal's coats can blend with the ice and snow. This posed some challenges in assessing their actual population in the past.

However, today's technology and equipment with thermal imagery allowed researchers to "see" animals, and the telemetry data helped estimate the number of animals on land and in water. Despite the success of gray seal conservation, complaints from fishermen in the area cannot be ignored.

In 2012, fishermen in Massachusetts complained of seals stealing their fish. "The seals just sit there and eat the fish out of the net as it's coming up into the boat," one said.

Popular Science pointed out that some groups even advocated for the culling of the seal population, which Professor Johnson decried as illegal and premature. He noted that there is little that scientists know about gray seals and that there is little evidence that culling their numbers could increase fishery yields or give positive effects for the ecosystem.