For the Weddell seal population study it's mid-season. Much has been accomplished by the Antarctica field research team. But still, much more awaits. Lead scientist Jay Rotella reported recently that approximately 575 pups have been tagged so far, which makes this season very likely to become another well above-average year for total pups born in the study area.
"Are you my mother?" Photo by Bill Link, NMFS Permit 17236.
Of the 575 pups tagged to date, 149 pups born to known-age mothers have been weighed. These pups will be weighed 3 times over the duration of the 30 to 45 day nursing period; and they also have been fitted with small temperature tags for the pup swim time project. The small temp tags record the surrounding temperature every six minutes, and are removed when the pups are also weighed again near weaning time.
Because the water temperature is a constant minus 1.8 degrees celsius but the air temperature can vary widely, it is easy to determine how much time the pups have been in the water learning swimming skills during the nursing period. The researchers have found a large variation in how much time different pups spend in the water with their moms learning important swimming and behavioral skills.
Mom and pup nuzzle in a swim hole in this photo by Bill Link, NMFS Permit 17236.
This season, much of the Erebus Bay study area is smooth 1st year ice. The seals can be seen for some distance when the weather is good. According to Jay Rotella, some of the team recently explored the study area by helicopter and found only a few places where seals can't be seen for a good distance. Those places are in the deepest part of the North Base of the Erebus Glacier Tongue over a pressure ridge where around 15 seals were sighted; and another group of 3 seals were sighted in the deepest part of the South Base of the Erebus Glacier Tongue. The team was able to reach these seals by traveling carefully over the more rugged multi-year ice terrain after the flight.
Another aspect of the population study includes taking photogrammetric measurements of seal mass with a small camera to compare with actual weight measurements obtained using a more traditional weigh sled. The team is working on developing a quicker and less intrusive way of getting weights on moms and pups alike.
This season a visitor with the project is Bill Link, a mathematical statistician with USGS.
He is also an accomplished photographer working under the auspices of the project's
NMFS Permit 17236. Many of the photos used in this season's field blog were taken by Bill Link. (Thank you, Bill!)
- Mary Lynn Price
Comments