Collecting rare seal recordings in the Ionian Sea

Mediterranean monk seals are the rarest seal species on the planet, with only a few hundred individuals living on a collection of islands throughout the Mediterranean. Conservation efforts are dependent on understanding their numbers and habitats, which can prove challenging due to their distributed range.

Amlin et al. presented underwater vocal recordings from a population of monk seals in the Ionian Sea, identifying 10 distinct vocalizations. By employing a combination of passive acoustic monitoring and underwater video, they were able to verify five of these calls, which made up the majority of recorded calls.

“This was very exciting for us, because there were no examples of verified underwater calls that we could find when we started this project, and this is the first time we’re aware of that direct evidence of the seals vocalizing underwater will be made available,” said author Angela Amlin.

The team placed a passive acoustic monitoring device near a known seal habitat for over two weeks, recording nearly 2,000 high-quality seal calls and classifying them into 10 types. This data, along with video verification of many of these calls, can help conservationists track seal populations and evaluate trends.

“We hope that our work — combined with others’ ongoing work using techniques and tools such as environmental DNA and unmanned aerial vehicles — enables scientists and managers to improve understanding of monk seal population status, trends, and distribution, which will enable implementation of effective conservation measures and protective policies,” said Amlin.

The authors plan to implement automated identification of some of these calls and expand the scope of their recordings to track short-term and seasonal trends in monk seal habitats.

Source: “Confirmed vocal activity of Mediterranean monk seals in the Inner Ionian Sea Archipelago, Greece,” by Angela Amlin, Luke Rendell, Nino Pierantonio, Carmen Andrés-Hervías, Giuseppe Notarbartolo di Sciara, Gordon Hastie, and Joan Gonzalvo, Journal of the Acoustical Society of America (2025). The article can be accessed at https://doi.org/10.1121/10.0036436 .