Scientists use technology to measure gray seal population

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Scientists use technology to measure gray seal population

June 20, 2017 - 01:22
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Scientists have used technology to survey the gray seal population to the New England and eastern Canadian coasts, thereby confirming the success of seal conservation efforts.

Seals camouflaged by snow and ice cover makes it difficult for scientists to estimate the animals' population size accurately.y.

Technologies like drones, thermal images and Google Earth helped scientists obtain an accurate picture of the population of gray seals to the New England and eastern Canadian coasts.

In a recent study published in the Bioscience journal, researchers using aircraft to survey seals on the beaches, islands and seasonal ice cover counted about 15,000 seals off the coast of southeastern Massachusetts. However, using technology yielded a different picture.

"Our technology-aided aerial survey, which used Google Earth imagery in conjunction with telemetry data from tagged animals, suggests the number is much larger--between 30,000 and 50,000," said David W Johnston, assistant professor of the practice of marine conservation ecology at Duke University's Nicholas School of the Environment.

The difference in numbers is due to the fact that seals spend much of their time at sea, where they are undetectable by land-based observation, and where it is hard and dangerous to track by boat or aircraft.

In another paper published in the Scientific Reports journal, drones equipped with thermal imaging technology were used to conduct aerial surveys of the gray seal populations in Nova Scotia's Hay Island and Saddle Island. The collected images were analysed using manual counting, and also by a computer-vision algorithm that did the counting based on the seals' temperature, size and shape of their heat signatures.

"Seal pups are born with a white coat, which makes them hard to see against ice or snow using traditional imagery. But they can't hide from thermal imagery," said Alex Seymour, a geographic information systems analyst at Duke University's Marine Robotics and Remote Sensing Center.

The difference in results were less than five percent, and the automated counts proved better at spotting seals visually hidden or obscured within the landscape.

"Computer-based assessments of seal populations such as this hold great promise in terms of accuracy and repeatability," said Johnston. "And 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."

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