Polartec Blog

This was B-232’s last season on the ice, and the goal of our 4 person field team (Dan Costa, Jenn Burns, Michelle Shero and Kim Goetz) was to quickly locate Weddell seals that we outfitted with satellite tags last Jan-Feb, and recover their tags. Over the winter months the tags transmitted information on animal location, diving behavior, and temperature and conductivity information from the water column. However, bandwidth and transmission constraints mean that not all the recorded data is recovered via the satellite link. Retrieving the tag allows us to recover all the collected data, and significantly improves the information on animal behavior and winter oceanography. This is particularly true for the late winter months, as wear and tear on the antenna that occurs when seals swim around ice eventually causes antenna breakage, and this further reduces the amount and quality of the data transmitted.  When we recover the tag, we also assess the physiological condition of the animal: this allows us to assess diet, how behavior influences growth and health, and to examine the relative impact of exercise on aerobic capacity. Samples collected during recovery are compared to similar samples collected when tags were deployed. For comparative purposes, additional, non-tagged animals are also handled.

While this season was short (just 4 weeks) it was amazingly productive. In the first week we were here, we completed all our refresher training and just 5 days after arriving we were out on the sea-ice recovering the first tag. By the end of our second week, we had 6 satellite tags in hand, and had handled 8 females (two had already lost their tags). This quick and productive start was assisted by tips from the B-009 and B-470 teams, which were keeping an eye out for ‘our’ animals and letting us know when & where they were spotted. And each team actually recovered a tag for us – B-009 found one on the sea ice, and B-470 retrieved one that was hanging on by a few hairs. And, B-199 reported that a tagged seal was occupying their fish hut & we were able to find the seal and recover her tag, too. There has been a great deal of collaboration and cooperation among the teams this season and it has really aided all our projects.

We also relocated two other of our females in areas where we could not safely work, and one female was only ever seen on days we could not handle her. All these females had already lost their satellite tags, but it was good to find them and see that each had successfully pupped this season. Only two females from the ‘local’ study were not spotted this year. Of the 10 tags we deployed in the north, we relocated and recovered the tag from one female, and found another female in an area that we could not work. Still, any tags recovered from this second group of females is a bonus, since we are much less sure where the seals will be, and don’t have the additional help of other science teams working in that area. In this recovery effort, we had great support from Helo-Ops and the pilots who flew long night flights over broad areas. As we finalize packing and get ready to head home with our 6 tags in hand (and samples from 12 adult females) we want to thank everyone who made this season such a great success.

Some images from the week

WS11-08 after her tag was removed in Tripp Bay. The tag is shown on the right *note that the antenna is starting to break off.

A Weddell seal pup getting one of its first swimming lessons by Hutton Cliffs, and an older pup starting to molt its lanugo pelage.

One of the well-preserved crabeater seal mummies, and students collecting samples from a mummified crabeater seal in the dry valleys.