19 November, 2003
Today we had a change in camp personnel. Dr. Brent Stewart left to return to California. His bunk was immediately filled by Dr. Robert Garrott, our project's PI, who arrived from Bozeman, Montana. Dr. Garrott will be here through the end of our field season.
Somehow, in all this journalizing, I never got around to profiling Brent. He has been collaborating with the Weddell Seal Project since 1996, and works with the Hubbs-Sea World Research Institute in San Diego as a Senior Research Biologist. Brent has studied the population biology, foraging and physiological ecology, and behavior of marine mammals and sea birds for over 25 years. His research expeditions have ranged from Greenland and Iceland in the North Atlantic south to Marion Island in the South Atlantic and Indian Ocean, in Russia's Lake Baikal, from the Beaufort and Bering Seas south through temperate, tropical and equatorial waters in the North Pacific Ocean, and in the Weddell, Amundsen, and Ross Seas of the Antarctic's Southern Ocean. His principal interests in these comparative studies has been discovering and understanding what habitats are important to these various large marine vertebrates, how they navigate and migrate over vast areas to find and use those habitats, how they hunt and capture prey necessary to sustain fasting periods and successfully reproduce, how they interact with each other (populations and species) while sharing habitats and resources, and how they respond and adjust to short and long term natural and anthropogenic changes in those key habitats.
When asked how he ended up as a globe-trotting marine mammal researcher, Brent responded this way. "I didn't start out with any plan to study marine mammals. In college I studied math, philosophy, English literature, music, and biology though exploration of wild, remote unvisited and unknown places. This was, I think, my key passion. A simple twist of fate led to a Master of Science program studying marine invertebrates, interrupted by a few unexpected disasters and another simple twist of fate found me training dolphins to help a friend with her Masters thesis. Somehow that all led to a 25+ year career as a field biologist exploring remote romantic places on this planet and studying various marine vertebrates, mostly marine mammals, that live in those wild and wonderful places....and earning a couple more graduate degrees in rather unorthodox ways along the trail. But mostly, I'm not really sure how it all got started and not too sure where it might be going. It's been a vagabond life, but I sure hope a lot of others can be so fortunate. Pitching up in the Antarctic surely is glorious. Though some might consider it the geography of despair because of how poorly adapted humans might be to live there, it might really be considered the geography of hope, as Wallace Stegner referred to another remarkable landscape, the American West."
Brent and his wife Dr. Pamela Yochem, a wildlife veterinarian, have been collaborating with this project since 1996. They will both return to Antarctica in January to continue their work on this project. In their work they are trying to supplement the long-term population biology research by applying remote sensing technology to document where Weddell Seals spend their time in the water column and geographically as they search for, and capture, prey. Small microcomputers called TDRs (time-depth recorders) that they glue to a seal's hair store measurements of hydrostatic pressure (converted to depth) every 5 to 15 seconds. This sampling interval is programmed before the microcomputer is attached. At that rate they can record the vertical location of a seal continuously for up to 8 months. The glue mounts fall off the seals when they molt in January and February. They have to recover these recorders to transfer the data by searching the colonies at various times to find, capture, and then unfasten the recorders from those glue mounts. The recovered data tells them what vertical habitats are key to seal foraging efforts and if these habitat preferences vary among colonies and between males and females of different ages. The TDRs also give them an index of the amount of effort that seals spend to forage because they can determine the timing and number of dives as well as their duration. In addition, they use satellite-linked radio transmitters to tell them where seals are geographically when diving and foraging. Those locations are sent to his email account daily as long as the few earth-orbiting satellites are detecting signals from the transmitters attached to the seals. Brent and Pamela are also evaluating the health of seals, using standard analyses of blood samples and veterinary medical inspections, to determine what kinds of infectious diseases the seals have previously been exposed to or may be suffering from now. Animals in poor health may be less capable or efficient at diving and foraging. This may translate into poorer survival or inability to reproduce as often. These effects may help explain patterns seen in the long-term demographic study.
Brent has an impressive roster of upcoming projects that will take him from the Channel Islands studying Elephant Seals, to Baja doing Grey Whale surveys, and on to Australia for a project looking at Whale Sharks. He is definitely seeing the world, one marine mammal at a time.
Weddell Seals dive
How far, how long, where are they?
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