Gray seals were once hunted almost to extinction in the coastal waters of New England and the shores of Canada. Now, their population has not just bounced back, but boomed, with the latest survey suggesting up to 50,000 of the creatures are happily living off the coast of Massachusetts.
Scientists have been able to make the most reliable census yet of seal numbers by using modern technology including drones, thermal cameras, and even Google Earth.David W Johnston of Duke University explained: “Past surveys based on traditional methods of counting, using occupied aircraft to survey seals on beaches, islands and seasonal ice cover, counted about 15,000 seals off the south-eastern Massachusetts coast. “Our technology-aided aerial survey, which used Google Earth images in conjunction with telemetry data from tagged animals, suggests the number is much larger – between 30,000 and 50,000.”
The seals were once hunted widely for meat, oil, and their skins, and had almost vanished from parts of the USA.
Numbers have been steadily rising since the 1980s however, with the population now thriving and spreading further south, with regular sightings as far south as New York and New Jersey.
A separate study in Canada also confirmed how successful conservation efforts have been in restoring seal populations there. It had always been tricky to count grey seals, particularly the pups, because they blend in with the snow and ice around them. That meant trying to see how many young were born each year was hit and miss using traditional tools like aerial photography.
However, researchers from Duke University used drones equipped with thermal imaging technology to survey enormous colonies on Nova Scotia’s Hay Island and Saddle Island.
Alex Seymour of Duke University said: “They can’t hide from thermal imagery … when coupled with new population survey approaches using drones or earth-observation imagery, they help us reduce surveying costs and risks, while increasing data quality.”
One of the best places to see gray seals in the wild remains Sable Island, an island 100 miles from the coast of the province of Nova Scotia where they breed in huge numbers every year.