As the Fur Flies: Tracking Fur Seals
Principal Investigators: Heather E.M. Liwanag & Carey E. Kuhn
Fur seals rely on their thick, waterproof fur to keep warm while they swim and dive in the ocean. To study fur seal movements and behavior at sea, scientists glue electronic tags to the fur. When it's time to retrieve the data, researchers either cut the top of the fur to retrieve the tag, or cut through a neoprene patch and leave the bottom layer of neoprene attached to
the animal. It is thought that the cut fur will be restored or the neoprene patch shed during the molt, but this has never been explicitly investigated. In fact, for many species we know
very little regarding the time it takes for the hair to fully regrow after being modified by tagging efforts.
Because fur seals rely exclusively on their fur for thermoregulation in water, they are ideal study subjects for investigating the long term impacts of instrumentation on fur function and recovery.
The loss of guard hairs may allow water to penetrate, severely reducing the effectiveness of the insulating layer of fur. Similarly, the presence of a neoprene patch glued to the fur
may affect the surrounding layer of fur by introducing water. These artifacts of tagging may affect the ability of the animals to insulate themselves while swimming and diving.
We plan to investigate the effects of electronic tag retrieval on the pelage of fur seals, and to assess the thermoregulatory consequences for the animals when the fur is
modified by tagging efforts. We chose the northern fur seal (Callorhinus ursinus) as a model because this species has the densest fur and forages in high latitudes during the
breeding season, where colder water temperatures may lead to thermoregulatory challenges. To assess the thermoregulatory consequences of instrumentation, we will measure the thermal
conductivity in water for (a) unmodified pelts, (b) pelts with the top layer of hair cut, and (c) pelts with a patch of neoprene glued to the fur. We will also place modified and unmodified
pelts into a hyperbaric chamber to determine the extent to which water is able to penetrate the fur when the animal is diving. Finally, we will follow known individuals of northern fur seals
that have been tagged in the current tagging efforts of the NOAA program, to examine the time it takes for the hair to fully regrow after being cut and for a neoprene patch to be shed.
This study will be the first to measure the thermoregulatory consequences of tagging artifacts for fur seals, and will help to determine the best method for tag attachment to
minimize those consequences. Fur seals are of conservation concern, and the northern fur seal in particular has recently experienced an unexplained decline in numbers. The northern
fur seal is currently listed as vulnerable on the IUCN Red List, and the Pribilof Islands/Bogoslof Island population is listed as depleted under the Marine Mammal Protection Act. Although the
northern fur seal appeared to be recovering over the past few decades since its initial depletion during the fur trade, its populations have recently been declining for reasons unknown. As
northern fur seal populations suffer precipitous declines in El Niño years, global climate change may contribute to and/or exacerbate their dwindling numbers. This project will inform
scientists of the best tagging methods, to minimize effects on the fur seals' insulation. It will also tell us about what happens when anything (like an injury) causes damage to the fur.
We're trying to save these amazing animals, one study at a time.
In May 2012, we participated in #SciFund, a crowdfunding campaign, to raise money for the purchase of a
hyperbaric chamber, a crucial piece of lab equipment that will allow us to test pelts to determine if water can penetrate the fur under pressure. This is important to understand, since fur seals
dive for their food and thus experience hyperbaric pressure under water. If water penetrates their fur, the fur seals can get cold and may have to cut their feeding dives short. A pressure chamber
will allow us to solve an important piece of the puzzle, and better inform scientists in their tagging methods. If we exceed our funding goal, it will allow us to increase our efforts to compare
tagging methods in the field, and to do more follow-up observations with fur seals that have been tagged. Although we did not reach our funding target, we will be able to move forward with the project
in the coming months. Thanks again to all the project supporters!
Mary Katherine Adams
Mary Beth Barnett
Anne Shirley Hahn
Vembar K Ranganathan
Krista De Las Alas
A. D. Fitzgerald