Seal Star Quality!

Tracked seal delivers data 

Every day brings surprises at the Piedras Blancas elephant seal viewpoint, but April brought an especially exciting seal to the beach. Docents spotted her on April 5, with two tracking devices attached. One was on her head, the other on her back. She was carrying messages from long ago and far away.

Such electronic tracking devices are used by the research team at University of California Santa Cruz campus, so Friends of the Elephant Seal docents notified them right away. Salma Abdel-Raheem, Ph.D. student in the Beltran Lab in the Department of Ecology and Evolutionary Biology, recognized the seal as one of her research subjects. The team worked with their colleague Dr. Dan Costa to get the State Park and National Oceanic and Atmospheric Administration permits required to go on to the beach and retrieve the devices.

 

All the pieces were in place to recover the devices on Easter Sunday, April 9. After carefully shooing away the other seals and giving the seal a sedative injection, they cut off the zip ties and electrical splicing tape holding the device to a mesh footprints glued to the fur. They also collected blood and tissue samples. Success!

 This journey began May 2022

The research team glued the tracking devices to this seal May 2, 2022 at Año Nuevo. The seal was two years old then, approaching adulthood from adolescence. She hauled out at Point Reyes a few months later, on September 19, and stayed to October 24, a typical juvenile haul-out.

“We tried to retrieve her tags during this period, but she was only accessible by boat and weather conditions were not favorable,” Ms. Abdel-Raheem said.

The seal left the beach on her next migration, and Piedras Blancas was the next they knew of her. That 342-day trip is the longest of any of the juvenile seals the team has tracked so far, nearly double the average trip of 184 days.

“We're really excited to see what she’s been up to in her year-long adventure!” Ms. Abdel-Raheem said.

 Successful foraging

She fed well during that migration, doubling her mass from 170 kgs (~375 lbs) in May 2022 to 344 kgs (~760 lbs) when they recovered her tags on April 9, more than any other seal the team has studied. 

She is beautiful and sleek, without any scars or defects. I thought she was absolutely perfect, a Rock Star of a seal. The FES docents started calling her Gigi.

Somewhere along the way, Gigi lost the VHF transmitter that allowed the team to find her on the beach. However, the tracking devices continued collecting data – salinity, depth, light, temperature, and accelerometers that measure the orientation of the animal in the water column as well as its speed and acceleration.

“We can put these data together to help us formulate an idea of what the seal is doing while out at sea. We can infer the number of prey capture attempts, the body condition via buoyancy, how much time the animal spends traveling, resting, or foraging, how the animal responds to changes in its environment,” Ms. Abdel-Raheem said. “These data are critical in informing our understanding of the ecology and physiology of this species throughout juvenile development.”

Along with Ms. Abdel-Raheem, the tag recovery team included her two lab-mates, Zea Premo and Milagros Rivera, and their adviser Dr. Roxanne Beltran. Zea is studying the development of diving physiology in juvenile seals by using the blood and tissue samples that they collect; Milagros is interested in the genetic diversity of northern elephant seals and uses the DNA samples to inform their research.

The mesh footprint that held the tracking devices will fall off as Gigi molts on the beach, now blending in among her sisters. Thanks, Gigi, and farewell.