Monitoring grey seal pupping 2025

A seal’s weight and body condition tell us a lot about its health and chances of survival.

For the past two years, the Gothenburg University Seal Population Dynamics Group has been involved in a project focused on monitoring the health, welfare, and abundance of Baltic grey seal pups.

Baltic grey seals are born in February or March, coinciding with the peak in sea ice. Ice is considered the optimal habitat for this species, but these days they are more often born into dense land breeding colonies.

A seal’s weight and body condition tell us a lot about its health and chances of survival. This is particularly true for grey seal pups as they need to pack on around 30 kg of blubber in their first three weeks of life to ensure their survival.

An optimal seal habitat is a suboptimal drone pilot habitat.

Using drones and machine learning, we can now estimate a seal’s weight from images alone. This means we can track indicators of colony health and individual pup welfare without disturbing the seals during this important time of their lives.

We are working to link these observations to changes in colony density to better understand how wild animal welfare might be impacted by changes in breeding habitat.

We can now estimate a seal’s weight from images alone.

Joining Mart Jüssi from Pro Mare, a group responsible for applied research and monitoring of seals, we spent more than a month on site in Saaremaa Estonia conducting drone surveys of the pupping sites. Working alongside Laura Stukonytė, a PhD student from Vilnius University, we also set up trail cameras to noninvasively capture behavioral videos and individual identification images of grey seal mothers.

Seals don’t care about international borders, so working with other Baltic countries to study seals will help the Sälfie-ID program in its goal to learn more about seal ecology.

Mart and Laura flying the drone, keeping an eye on the seals with no disturbance.