Fewer Weddell seals than previously thought

Fewer Weddell seals than previously thought

Wed, 06/10/2021 - 13:54
Posted in:

The first-ever global population estimate of Weddell seals in Antarctica has been completed, with the help of more than 330,000 international volunteer citizen scientists.

Weddell seal and her pup.
Weddell seal and her pup.

Led by researchers at the University of Minnesota Twin Cities, the team of citizen scientists used hundreds of high-resolution satellite images of areas of the Antarctica to manually count the seals.

Publishing a paper on their findings in the Science Advances journal, the researchers concluded that there were about 202,000 sub-adult and adult female Weddell seals in Antarctica in November 2011. This number contrasts with previous estimates of female Weddell seals at about 800,000. 

(Male Weddell seals were not counted as most of them were under the sea ice defending their territories when the images were taken.)

"That doesn't necessarily mean there has been a big decrease of Weddell seals recently, but instead this is probably a more accurate count that we can use as a baseline to determine change over time," said lead author Michelle LaRue, a University of Minnesota research associate in the Department of Earth and Environmental Sciences.

In addition, the researchers also discovered that the seals preferred to be near the continental shore but also near deep water. This is perhaps due to the locations of their predators and prey.

Another interesting discovery is that they appeared to prefer being near Emperor penguins, but only if there were not too many of them. LaRue explained, “There seems to be a trade-off. It's good to be near Emperor penguins but only if the penguin colony size doesn't get too big and there is not too much competition for food.”