An unmanned drone soaring over the Arctic recently had two missions: Take pictures of the declining sea ice and pinpoint the location of seals on chunks of the ice.
The ScanEagle, as the aircraft is called, is the first of its kind to monitor sea ice and seals in this remote area, eliminating the need for pilots and observers on such a risky mission, said Elizabeth Weatherhead, a study team member from the University of Colorado at Boulder.
Human-produced greenhouse gases that are building up in Earth's atmosphere are contributing to the Arctic's warming and sea ice loss. This sea ice is critical for the survival of Arctic animals on land and in the water, and the mission will help identify locations of immediate concern.
"Because ice is diminishing more rapidly in some areas than others, we are trying to focus on what areas and types of ice the seals need for their survival," said Peter Boveng, a study team member from the U.S. National Oceanic and Atmospheric Administration (NOAA)'s Alaska Fisheries Science Center.
"By finding the types of ice they prefer, we can keep track of that ice and see how it holds up as the Arctic sea ice extent shrinks," Weatherhead said.
Weatherhead gave a presentation on the subject at the 2010 fall meeting of the American Geophysical Union being held this week in San Francisco.
The four species of Arctic seals of most interest to the research team are the bearded, ringed, spotted and ribbon seals, each of which rely in some way on sea ice for breeding, resting and as a safe haven from predators.
This month, NOAA's Fisheries Service proposed listing the Arctic ringed seal as threatened under the Endangered Species Act due to diminishing sea ice and snow cover. Arctic ringed seals do not come ashore, but use sea ice for whelping, nursing and resting. Ringed seal pups are born in snow caves on the ice, and their survival can be affected by snow depths and the timing of spring snowmelt and ice breakup.
The ScanEagle was launched in May and June of 2009 from the NOAA vessel McArthur II over the Bering Sea west of Alaska. The drone has a 10-foot (3-meter) wingspan and is owned and operated by the University of Alaska in Fairbanks. Image recognition software was used to spot seals in 27,000 images that were collected during the flights.
"The results show that the seals have distinct preferences for specific types of ice, demonstrating that ice extent is not the only factor affecting seal populations," Weatherhead said.
"Biologists are thrilled about the image recognition software because it could change the way we monitor seal populations," Weatherhead said. "We can send an unmanned craft out from a ship, collect 4,000 images, and have them analyzed before dinner. This is a great example of physicists working closely with biologists who are concerned with the health of seal populations."
Typically, seals appear in less than 1 percent of the images, Weatherhead said. But on the ice floes or ice edges where they are found, the software can help researchers identify seals by species. In the future, researchers might be able to identify the relative age and gender for some seal species. The software could even be adjusted to look for polar bears and their tracks.
Weatherhead said the team wants to combine its results with forecasts not only of future sea ice extents, but also of future ice characteristics that will allow for predictions regarding the impacts of changing and disappearing ice types on seal populations.