Weddell Seal Science

A Banner Field Season!

The end of the 2011 Antarctica field season for the Weddell seal population study has come upon us, and as always, all too suddenly.  The number of new pups being born on the ice slowed then diminished to none.  

The air temperature, well below zero in the early season, stabilized right around 20° F, nearly t-shirt and shorts weather for us.  (And indeed we could often be seen down to our base layers and still sweating while tagging seals!) 

The pure white snow petrels with beady black eyes and black bills arrived, to my personal great joy, though heralding a dreaded moment for us:  the pulling of the field camp.  Because of its location on the sea ice, the heavy equipment operators understandably want to pull the camp before the ice conditions become too unreliable.  A few days ago this was done, our huts now sitting safely on rock at McMurdo Station.  We completed our field work concurrently, and shifted our attention to the reorganizing, packing, and returning of camp and field gear, all of which is mostly completed as of now.

So, after all the effort of the season, what did we accomplish?  Most significantly, in continuation of the 40+ years of data collection without missing a SINGLE YEAR, we have tagged another MASSIVE number of pups (similar to last year's all-time record): 617.  That's over 100 pups per crew member.  We were also able to obtain the three desired weights (these being at birth, mid-lactation, and weaning) of 128 pups.  We successfully deployed temperature tags on 50 of those pups, obtaining some great insight on the behavior of pups learning the ins and outs of swimming in Antarctic waters!  

It has been a great season for the crew, which put in some incredibly long days (eating dinner at midnight!) and endured with great enthusiasm the mentally and physically challenging extreme environment of Antarctica.  And we even continue to hang out together in McMurdo!

Our biggest thanks goes out to the National Science Foundation, the U.S. Antarctic Program, and the support we receive at McMurdo from Raytheon Polar Services and various other contractors--there is no chance of our work being accomplished without this support.  And thank you, kind reader, for keeping a keen attention to Weddell seal science and desiring to learn more about these unique creatures of the ice and sea.

- Jesse DeVoe

 

Weddell Pups: Weighing In

Weddell seal pup mass (weight) at weaning is important to seal survival, and is an essential measure of maternal investment by Weddell moms in their pups.  Weddell moms usually fast during the 5 to 6 week nursing period.  And for every pound a pup gains during the nursing period, the mother can lose around 2 lbs of her own body mass.  Weddell pups can more than triple their birth weight before being weaned, so there is a very large transfer of energy from mom to pup during this nursing period.

The Weddell seal population and mass dynamics project has published a number of research papers to date on Weddell seal reproductive costs and the relationship of pup mass to seal survival.  The researchers continue to learn more every year about this long-lived apex predator and how it interacts with its changing Antarctic environment.

A crucial part of the Weddell seal research team's field work involves weighing pups at 3 different stages during the 5 to 6 week nursing period, with the first weighing taking place a day after birth, a second weighing around the mid-nursing period at 20 days, and a third weighing near weaning at around 35 days.  The 35 day pup weights range from around 150 to 280 lbs (68 to 127 kg).  In the images below, field researchers weigh a large pup as the mom looks on.

Also during the 35 day weighing, researchers will retrieve temperature tags from those pups that received the small temperature sensor/recorders.  "Out of the 57 temperature tags we deployed on pups this year, we have successfully recovered 16 so far.  We know that three of the tags have been lost, so we are crossing our fingers for getting the remaining 38 by the end of the season," says field researcher Jesse DeVoe.

In the image above, data from one of the small temperature recorders is displayed in graph form.  Because sea water temperature under the ice is a constant -1.8° C (28° F) but the surface temperatures on top of the sea ice can vary widely, researchers are able to deterimine when pups are in the water based on the data recorded by the temperature tags.  DeVoe notes, "The data retrieved so far shows lots of swimming pups!"

- Mary Lynn Price

Field Team Shifts Gears

In the photo above by Weddell seal field researcher Jessica Farrer, double lenticular clouds can be seen above the field team's Erebus Glacier Tongue sea ice camp. The remote field camp location gives the field team better access to the many Weddell seal pupping colonies studied by the Montana State University based project in the Erebus Bay area of Antarctica's Ross Sea.

The field team reports that approximately 525 pups have been tagged so far this season in the Erebus Bay study area. Pup births in the Erebus Bay area have now nearly ceased, and most of the pups are already in the water learning how to swim with their moms. The team is now shifting its focus from tagging new pups to weighing the pups at mid-lactation and weaning.

In the image below, field researchers Darren Roberts and Jessica Farrer work as a team to affix a small tag to a Weddell pup's rear flipper as the mom looks on. This pup will be added to the extensive database of this long-running population and mass dynamics study.

If the age of the Weddell mom is known, the pup may be weighed at tagging, then weighed again midway through the nursing period, and once more at weaning around 5 to 6 weeks after birth.

The mass of Weddell seal pups is very important to their survival. Weddell seal researchers are gaining new insights into the environmental and individual factors that affect the mass of Weddell moms and their pups, and consequently seal survival.

Here's a short video about some of the recent research work of the Weddell seal project investigating the role of Weddell seal pup mass and pup swimming behavior in Weddell seal survival:

- Mary Lynn Price

Weddell Seal Surveys

In addition to tagging all of the new pups born in the Erebus Bay Weddell seal study area, and weighing a select number of moms and pups, the Weddell seal field research team conducts between 6 to 8 surveys of the entire study area every pupping season to take a census of all the Weddell seals in the area.

During these survey days, the individual tag numbers of all Weddell seals seen on the sea ice are recorded by the team.  Conducting these surveys between 6 to 8 times throughout the study area over the course of the pupping season ensures that nearly all female Weddell seals that use the study area are detected at least once during these annual surveys. 

In the image below, field researchers Jesse DeVoe and Thierry Chambert prepare to tag two pups that appear to have been born to the same mom.  While it is unusual for Weddell seals to have multiple births (more than one pup per season), it can occur.  However, it is rare for both of the pups to survive.

- Mary Lynn Price

A Very Busy Field Season!

Heading out each day from the remote field camp on the sea ice, Weddell seal team researchers have been extremely busy visiting the pupping colonies throughout the study area here in Erebus Bay.  New seal puppies are tagged, and some of them are weighed.  Then all are added to the extensive database of Weddell seals in the ongoing Weddell population and mass dynamics study.

Last season was a record year for number of pups born in the population study area with 610 Weddell pups added to the database.  While it's still far too early to determine if this will be another year of higher than average pup births in the area, it's definitely off to a great start with 327 pups tagged and added to the database so far this season!

- Mary Lynn

Happy Camper 2011

Weddell seal project field team members deploying to Antarctica for the first time are all required to complete a two day "Snow Craft I" course often referred to as "Happy Camper" school. 

This year our new field researchers Darren Roberts, Colleen Siudzinski, and Michael Yarnall all completed the Snow Craft course. Darren Roberts captures some of the team's field training experience in this short video edit of his Happy Camper GoPro camera imaging...

 - Mary Lynn Price

Our Sea Ice Camp Now In Place!

Our remote field camp on the sea ice of Erebus Bay is now in place, and the view is spectacular!  This season we're located near the Erebus Ice Tongue just off the route to Cape Evans.  Erebus Ice Tongue is a fascinating glacial formation that is very distinctive in satellite imaging of the Ross Island area where we're located.  The tongue is actually a long narrow sheet of ice formed where the end of the Erebus Glacier projects out into McMurdo Sound.

Perhaps the most dominating feature of the entire area here is Mount Erebus (12,448 ft.//3794 m), the southernmost active volcano on Earth, named by polar explorer James Clark Ross after one of his ships.  Mount Erebus was first climbed by members of Ernest Shackleton's party in 1908.

From our field camp's large kitchen hut window, we have a great view of Mount Erebus, Mount Terror (another smaller inactive volcano named for Ross's other ship), and Hutton Cliffs where one of the larger Weddell seal pupping colonies is located.

Below is a view of our field camp in place as the sun dipped near the horizon, with Mt. Erebus in the background.

The field team is now in full gear and the Weddell seal pupping season is getting underway.  We'll have more on our field team and their work in future posts, so please stay tuned!

- Mary Lynn Price

A Bit of Background on the Study

Preparations and training continue for our 2011 field season here in Antarctica.

As a bit of background on the project, this Weddell seal population study has been ongoing for well over 40 years, and has resulted in very long-term records that follow individual Weddells over their lifetimes. We have a new History section on our web portal about the long history of this project.

Here's a short video from our website multimedia section on studying Weddell seals…

The Weddell seal study database covers a time period for long-lived mammals that is unique in the scientific community.  Because of this, scientists are able to study factors influencing how the various population vital rates, such as reproduction and survival, are influenced by annual environmental changes, and how the yearly cohort into which a seal is born influences its long-term population contribution.

The scientists are also investigating how individual variation in Weddell seals interacts with environmental variability that gives rise to differences in individual fitness, and the effect this may have on the overall Weddell seal population.

- Mary Lynn Price

Antarctic Field Prep Continues

Deployment to Antarctica for research work through the U.S. Antarctic Program involves a number of unique travel aspects. Weddell seal research team members travel initially to Christchurch, New Zealand, where everyone on the field team is issued extreme cold weather (ECW) clothing.  From Christchurch, the field team then boards a C17 military transport aircraft operated by the U.S. Air Force for the flight to McMurdo Station.

Here at McMurdo, logistical preparations and specialized training for deployment into the field are continuing. Because the Weddell seal field research team will be working from a remote field camp on the sea ice, several specialized training courses are required, including a two day "Snow School" (genially referred to as "Happy Camper School") which provides vital information and skills training for working safely in the Antarctic field--or a one day refresher course for those who have recently completed the training--and a day long "Sea Ice Course."  Additional courses cover everything from snowmobile handling and light vehicle training to field communications.

The field team has a very busy week ahead!

- Mary Lynn Price

 

Field Team Now at McMurdo Station!

The main group of the 2011 Weddell seal research team is now at the U.S. Antarctic base, McMurdo Station, and is ramping up preparations for deployment into the field. "The next week or so will be full with training (Happy Camper training for the new crew members!), logistics, obtaining gear and supplies, and setting up field camp," notes field researcher Jesse DeVoe.

The field research team this season includes Principal Investigator Bob Garrott, Thierry Chambert, Jessica Farrer, Jesse DeVoe, Darren Roberts, Colleen Siudzinski, and Michael Yarnall.  I will be joining up with the team now in Antarctica in just a couple of days as field videographer.

Co-Principal Investigators for this Weddell seal research project are Bob Garrott and Jay Rotella, professors in the Ecology Department at Montana State University, and Don Siniff, professor emeritus at the University of Minnesota.

Here's a short video introducing the beautiful Weddell seals that are the subject of this project. This video screened a few weeks ago as an Official Selection at the 2011 San Diego UnderSea Film Exhibition. Hope you enjoy the video!

- Mary Lynn Price