Using eyes in the sky to locate seals in the rapidly changing Arctic

Ringed seal next to the breathing hole on the fast ice of St. Jonsfjorden, Svalbard. Credit: Aeria (Eelke Folmer) / NIOZ / WUR

This summer, researchers were able to collect stunning drone images of ringed seals and walruses. In one fjord, St Johnfjorden, twelve ringed seals were found scattered throughout the fjord, resting on fast ice. However, getting close to and identifying these individuals is a major challenge. Since polar bears hunt ringed seals, any mammal—whether it walks on all fours or two feet—will be avoided at all costs.

“Using a drone, we were able to take high-resolution images of annular seals on the ice resting next to their breathing holes. Based on these images, the species can be easily identified,” says Gert Artes, project lead for the Arctic Seal Project. For this specific region, the researchers also obtained Maxar satellite images.

Since the ice is landlocked and does not move, the locations of the breathing holes are practically fixed. Therefore, researchers can match individual seals on the drone’s image directly to the breathing holes visible in satellite images. “Although we were aware of the potential of this satellite imagery in observing mammals from space, we were shocked to notice white streaks across the ice shield connecting the seals’ breathing holes. In this remote and hostile environment, this can only mean one thing, pathways Polar bear “.

Machine learning to count arctic mammals

The resolution of satellite images has improved greatly in the past decade. These satellites, which orbit the Earth at an altitude of more than 600 km, can image anywhere on the Earth’s surface with a resolution of 30 x 30 cm. By downsizing high-quality drone images to a resolution of 30 x 30 cm, researchers can create an image that simulates satellite images taken from space.

Ultimately, these images can then be fed to a machine learning algorithm and used to train a file neural network‘,” says Jeroen Hokendijk, a PhD candidate, who was part of the research team and is working with EPFL to further develop these technologies. By applying this trained network to satellite imagery, the researchers hope to be able to automatically detect seals in these remote and hostile areas.






Credit: Film by Frouke Fey, Drones by Aeria/Eelke Folmer

Arctic seal species use ice differently

Seals and walruses are particularly common in the Arctic regions. Each of these species has its own unique characteristics and relationship to sea ice.

Ring seals, for example, make breathing holes in sea ice installed on the coast. These breathing tubes can be several meters long and connect the sea water under the ice with the air above. By using their claws on their front fins, they prevent these breathing holes from freezing. During the long, dark winter months, these breathing holes are covered in snow. These snow dens provide their young ones with some protection from the harsh conditions outside.

In contrast, harp seals rest and give birth on drifting ice. This ice pack covers most of the Arctic in winter, and connects all land masses in the polar region, but decreases in size during summer months. Unlike fast ice, an ice pack drifts and can move several kilometers per day.

sudden changes in current and Wind direction It can quickly cause the birthing platform of the harp seal to collapse. Walruses also benefit from an ice pack, but individuals can also be found resting on the ground. Also, during this summer’s Svalbard research expedition, researchers were able to collect drone images from Walruses that may help others develop similar ones. machine learning techniques of this type.

  • Using eyes in the sky to locate seals in the rapidly changing Arctic

    A polar bear with a cub on one of the frozen fjords of Svalbard. Credit: Jeroen Hokendyk

  • Using eyes in the sky to locate seals in the rapidly changing Arctic

    Walruses congregate at one of the unloading sites in Svalbard. Credit: Aeria (Eelke Folmer) / NIOZ / WUR

  • Using eyes in the sky to locate seals in the rapidly changing Arctic

    A windless day in the Fjords of Svalbard. Credit: Jeroen Hokendyk

Change home quickly

Ultimately, the researchers hope to use these remote sensing techniques to locate seals in the Arctic. because of Climate change, Their home is changing rapidly. This is especially the case for the North Barents Sea and the islands of Svalbard and Franz Josef Land.

This region is the fastest warming place on Earth, with average temperatures rising by 2.7°C per decade, and up to 4°C per decade during the fall months. Therefore, knowledge of the habitats on which seals depend is urgently needed to study the impact of climate change and the conservation of this species.


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Presented by the Royal Netherlands Institute for Marine Research

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