From Mike Goebel of SWFSC:
“We will deploy these on Chinstrap penguins and Antarctic fur seals as part of an over-winter study of
habitat use by these species. We know that fur seals can range as far north as
the Patagonia shelf in the Atlantic but under some conditions they remain
foraging all winter south of the Polar Front. They can also spend the winter
off the coast of southern Chile. To what extent they use these different
habitats from year to year however, is unknown. Your instruments will help us
to determine how much variability there is from year to year and what
oceanographic conditions change behavior and location over-winter. Even less is
known about Chinstrap penguin habitat use during the winter; how far they range
and where. This is mostly because their smaller size prevents using larger
satellite-linked instruments to track animals at sea for many months. The size
of instruments is in a large part determined by power and battery requirements.
Your instruments are innovated in that they supplement power use with a solar
charger and use both light and geomagnetism to determine location with relatively
little power. We're excited to give them a try and advance our knowledge of how
these important species survive over-winter in Antarctic waters.”
SeaTag-GEO was developed to be used as a supplement to
plastic ID tagging projects. The low cost (under $400 on low quantities) and
improved accuracy over light-based positioning are two major factors in SeaTag’s
success.
The SeaTag product line including GEO, SOL, and MOD uses
a 3-axis magnetometer to measure the intensity of the Earth’s magnetic field. The
tag is then able to determine it’s latitude from this data. Through our initial
tests we have seen an average accuracy of 35 nautical miles. However, through refinement
we expect the overall magnetic error to decrease.
The tag does not use any batteries. Instead, the tag is wrapped in
a solar cell. The sun (or powerful light source) charges the aerogel capacitor
through the solar cell. While the cell is collecting the light data to
charge the capacitor it also measures sunrise and sunset. With these two points
the tag determines noon time, or longitude. The benefit to this approach is
that there are no battery failures (ie: premature battery depletion).
