Update On Sea Ice Conditions And The Work Of The Field Team From Lead Scientist Prof. Jay Rotella

Report From The Ice By Dr. Jay Rotella:

Over the past 8 days, the 2025 field season has gotten up and running well. The field season was a bit late to get started due to issues getting the team to McMurdo Station from Christchurch, New Zealand and due to some bad-weather days in the study area.

*Playful Weddell pup with mom in Erebus Bay, Antarctica. Photo by **Dr. Nancy Chen**.*

The seals, of course, are right on schedule, and the peak of pupping coincided with the start of our field work this season. The result is that our team got started right in the thick of pup births, and many pups that we’re encountering and tagging are 7-14 days old. That makes things a touch more challenging, but we’ve got safe procedures in place that are working well.

A photo of the Dellbridge Islands in the Erebus Bay study area taken on 10/18/2025 after the storm showing Inaccessible Island completely surrounded by water (right center) and the end of the Erebus Glacier Tongue visible at the current sea ice edge in the far left of the photo. This makes access to the northern part of the study area impassable to snowmobiles via the normal route. Photo by Cameron Hassman, courtesy the “McMurdo Sea Ice Report” from 10/20/2025 prepared by Stine Ornes, Sea Ice POC with McMurdo Field Training | Search and Rescue.

Another challenge for the 2025 field season is that a strong storm in mid-October blew some sea ice out of our study area that included a critical portion of our snowmobile route to the northern half of our study area. That means that we couldn’t get to the northern colonies in October. In most years, the northern colonies are home to just over half of the mom-pup pairs in the study area, so it’s important to work there. We finally were able to fly to the area on November 6th, 1 week after the peak of pupping, and the team tagged more than 100 pups that day while traveling among locations on foot rather than snowmobiles. We’re still working on plans for accessing the north side of Erebus Bay on a regular basis and should know a lot more in a week or so.

Project photo from 2020 showing a supply cache with Scott tents placed in the Erebus Bay study area north of the Erebus Glacier Tongue (EGT) during that season when access to the northern Weddell seal pupping colonies was cut off to snowmobile travel, as well, and helicopters were used to transport the field team to the north side of the EGT to work.

This is a good reminder of the challenges that long-term projects like this one face over the decades. The key is to do all possible to keep the data collection as consistent as possible while working safely in the conditions we’re given each year. So far, the project has done a great job of keeping the long-term data intact. We’ll certainly do our best to do so again this year. And it’s also important to keep in mind that years like this one, with different sea-ice conditions and areal extent are extremely valuable for learning how the seals respond to different environmental conditions.

– Prof. Jay Rotella
Principle Investigator
Erebus Bay Weddell Seal Population Study

Weddell Seal Science Field Blog