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Person points a camera at a seal.
Photo Credit: Peter Rejcek (Marine Mammal Protection Act #17411)
Scientist Linnea Pearson takes a infrared thermo-graphic image of a Weddell seal female to see if it is losing heat to the environment. The researchers want to know if body heat changes during the molting process when follicle growth requires more energy from the animal.

Project heats up

It takes a little longer than usual to sedate the 11-year-old skip breeder female. Veterinarian Rachel Berngartt errs on the side of caution when administering the sedative, a cocktail of anesthesia and tranquilizer. She constantly monitors the health of her patient, checking respiratory rate and the animal’s gums – still pink, so blood is flowing well.

“It’s good to have a designated veterinarian to monitor the health of the animal. That allows them to do their job,” says Berngartt, a veterinarian in Alaska who is also the clinical director of the Gastineau Humane Society External Non-U.S. government site.

“Them” is the rest of the research team – Burns, graduate students Linnea Pearson, Amy Kirkham and Michelle Shero, along with Julie Richmond, an assistant professor of biology at the University of North Florida and a former grad student under Burns.

This is Richmond’s first trip to Antarctica, though she has studied pinniped populations in other places, including a long-term project that has captured, studied and released more than 700 Steller sea lions in the Northwest over the last two decades.

Infrared image of a seal.
Photo Courtesy: Jenn Burns
Infrared thermography image of the dorsal side of a Weddell seal that pupped late in the season. The cold parts (blue) of the seal are where her fur is wet from laying on the ice, and the warm (red) areas are dry. Taken with a FLIR T450sc IRT camera, with 340 x 260 resolution. Image was captured at a distance of three meters from the animal.

“It’s definitely easier to capture and sample Weddell seals compared to Steller sea lions or harbor seals. Each species has its own quirks and challenges to capturing and working with them,” says Richmond, who is a distant relative of Nathaniel Palmer, an American seal hunter and polar explorer who was among the first to discover the Antarctic Peninsula.

“I’ve always been intrigued by the sea and exploring new areas, new ideas. It’s phenomenal to be down here,” Richmond says.

Her expertise is in marine mammal growth, development, nutrition and the role of hormones. Some of the blood samples taken from the heavyweight skip breeder, now gently snoozing away, will be used to analyze hormones involved in reproduction and possibly the molt process.

Before any biological samples are taken – and prior to even approaching the animal – Pearson first uses a thermal imager the size of a digital camera to look at the Weddell seal’s heat signature. The image looks like something out of the Predator movie, the seal a cool blob of color on a cold landscape.

A similar image will be taken in a couple of months when the animals are recaptured for a second assessment. If molting, the heat signature should change, as the skin temperature needs to be much higher to stimulate hair follicle growth, Pearson explains.

“It would make sense that they’re losing more heat,” she says.

A look ahead

The 11-year-old female is one of 24 Weddell seals the team captured and released for the study, which includes three categories of animals. There are the skip breeders, females that pupped early in the season and a group of moms that gave birth toward the end of the pupping cycle.

Tag and instrument on seal flipper.
Photo Credit: Jenn Burns (Marine Mammal Protection Act #17411)
The small instrument in the middle of the seal's hind flipper is a time-depth recorder that will log all the animal's dive behaviors (duration, depth, haul-out time) until the animals are recaptured. Instruments glued to the animals elsewhere would fall off as the seals molt.

This is the first of at least three field seasons for the group, some of whom will return in the second half of the 2013-14 austral summer to attempt to relocate the same animals, which carry radio tags for tracking, along with instruments that record activity such as how much time each spends in the water.

The scientists will reassess each animal’s condition, including an ultrasound to determine if a female is actively pregnant. It’s not entirely clear what factors cause a seal to “abandon” its pregnancy and skip a pupping cycle – another question to answer.

“The skip breeders we’ve handled this year have been in phenomenal condition. They’ve been huge – fat,” Burns says. “Any idea that these seals weren’t in sufficient condition to produce a pup in October or November goes right out the window. These animals are in great shape.”

The work in January and February will also include a census of all the Weddell seals the researchers locate, so they can note the molt status at that time. The MSU database will provide the reproduction history of each female the researchers find. Pearson will re-image each animal’s thermal signature.

Eventually, Burns’ team will develop predictive models based on their work and previous studies that will allow them to run scenarios that would suggest possible outcomes from environmental changes based on what is known about Weddell seal physiology and ecology.

“We don’t have all the empirical data yet, but we think this will be a benefit to the larger community of mammal researchers,” Burns says.

NSF-funded research in this article: Jennifer Burns and James Ward Testa, University of Alaska Anchorage, Award No. 1246463 External U.S. government site. Marine Mammal Protection Act #17411.