Studying leopard seals in Antarctica

Adult female leopard seal (“Violet”) with a satellite instrument on her back. NMFS permit #19439. Photo by Dan Costa.

Our research team, with the self-appointed nickname of Seal Team 5, is on our way back from a five week trip to Antarctica where we were studying the feeding ecology and physiology of one of the top predators in the Southern Ocean: the leopard seal. Our team consisted of five researchers from the University of California Santa Cruz, Colorado State University, Baylor University, and the U.S. Antarctic Marine Living Resources program and included experts on pinniped (seals, sea lions, and walruses) behavior, ecology, and physiology. Even though leopard seals are relatively common in the Southern Ocean and around Antarctica, we know surprisingly little about their life history and basic biology. That’s where our team comes in!

Seal Team 5 (from left to right): Dr. Daniel Costa, Dr. Mike Goebel, Dr. Steve Trumble, Sarah Kienle, and Dr. Shane Kanatous. Selfie photo credit: Sarah Kienle.

To get to our study site, we traveled by plane from our respective cities in the United States to Punta Arenas, Chile, and then we hopped on a National Science Foundation ship–the ARSV Laurence M. Gould—which took us to our final destination: Cape Shirreff. Cape Shirreff is a peninsula bordered by a glacier on Livingston Island in the South Shetland Islands off the Antarctic Peninsula, and it was the ideal study site for this project because there is an increasing population of leopard seals that regularly come ashore. Another unique characteristic of Cape Shirreff is that it is now ice-free, which makes it a window into the future, allowing us to see how Antarctic species adapt to an increasingly ice-free environment.

After a week of travel by plane and boat, we made it to Cape Shirreff and immediately started our fieldwork. Our daily routine consisted of hiking around the Cape looking for leopard seals. Once someone spotted a leopard seal, they radioed back to camp, we’d pack up all our extremely heavy gear, and then we’d hike out to the beach where the leopard seal was spotted. Over the course of three weeks, we worked with ten leopard seals. When we first had proposed this project, we expected to work only with adult female leopard seals, as adult females are by far the most common age class and sex seen at Cape Shirreff. However, we were thrilled to work with not only six adult females but also three adult male leopard seals and one juvenile leopard seal!

Adult male leopard seal (“Shaggy”) with a satellite instrument on his head. NMFS permit 19439. Photo by Dan Costa.

We instrumented each seal with a tag that transmits data through the satellite network and records daily information on the leopard seal’s movements, locations, and dive behavior. We also took a bunch of measurements (ex. lengths, girths, mass) and tissue samples from each leopard seal. Together, these measurements and samples give us an incredible wealth of information about the seal’s body condition, health, diet, trophic position, and muscle performance. We are also excited to see how these ecological and physiological metrics will differ among males and female leopard seals and between the adults and the juvenile leopard seals!

And just like that, our three weeks at Cape Shirreff were up. We were picked back up by the ARSV Laurence M. Gould and are now on route to Punta Arenas, Chile. The whole Seal Team 5 is incredibly pleased with what we accomplished at Cape Shirreff, and we are looking forward to analyzing the data we collected and keeping track of our tagged seals in the upcoming months.

-Sarah Kienle, May 12, 2018

Leopard seal asleep on a beach at Cape Shirreff. Photo by Sarah Kienle.