So far, this has been a very interesting pupping season for the Weddell seals of Erebus Bay, Antarctica, and the Weddell population study's research field team. There is change this year in both the number of pups born in the study area compared to the past few years, and the location of the sea ice edge this pupping season.
Project lead scientist Dr. Jay Rotella notes, "All continues to go very well with the 2016 season. Most of the pups for the 2016 season have now been born. It appears that the number of pups this year will be quite close to the long-term average. The team has identified and tagged over 400 pups and completed the 1st survey of the population. They will try to obtain 6 surveys between now and Dec 8th to obtain data on the size of the population that’s using the study area this year and to assess the composition of the population." In comparison, last season there were 658 Weddell pups born in the study area.
As for the sea ice edge just beyond the study area, Rotella notes that, "The ice edge is farther north this year than it’s been in recent years. Given that, it will be interesting to see how the numbers of pups and adults that are seen this year compares with what has been seen in other years."
Below are two Sea Ice Maps courtesy Brad Herried of the Polar Geospatial Center (PGS). The maps show in the upper right area where the sea ice edge is this season. In the top map for this year, no sea ice edge can be seen because it is further north beyond the map area. In the 2nd Sea Ice Map from around this same time of year in 2015. In start contrast to this year, the sea ice extent was much further south in McMurdo Sound, and much closer to the study area pupping colonies. Sea ice extent affects the distance the Weddell seals must swim initially to get to the pupping colonies, and how much distance there is between the seals and their predators beyond the sea ice edge. Sea ice extent can also affect how much bio-production is going on under the ice, and how much in the way of food resources might be available for the seals.
Says Rotella, "In addition to understanding the lives of individual seals, the project also seeks to understand how population size and structure varies with environmental conditions. Thus, obtaining data from years with differing conditions is vital, and years such as this are very interesting and help greatly."
In another interesting update from the research field team on the ice, a crabeater seal is photographed lounging on the ice next to a Weddell seal. Crabeater seals are occasionally seen in the study area, and are one of the 4 species of seals that live their entire lives in Antarctica, including the Weddell seal, the Ross seal, and the leopard seal. See if you can spot the differences between the crabeater and the Weddell seal!
- Mary Lynn Price