Polar Bears International

12/17/2014 3:26:03 PM

New Study: Polar Bear Capture and Release Does Not Adversely Affect Bears

What polar bear researchers knew to be true is now backed up with a mountain of empirical data. A new analysis has shown that 40 years of polar bear research based on a live capture and release-based research program had no adverse long-term effects on the feeding behavior, body condition, and reproduction of polar bears, according to a new study by the U.S. Geological Survey.

According to the USGS news release, "The study used over 40 years of capture-based data collected by USGS from polar bears in the Alaska portion of the southern Beaufort Sea. Scientists looked for short and long-term effects of captures and deployment of various types of satellite transmitters on polar bears in the Alaska portion of the southern Beaufort Sea."

Researchers found that polar bears returned to near-normal rates of movement and activity within two to three days following capture and release, and that repeated captures over multiple years of study did not alter health or reproduction.

They also found that physical condition, reproduction, and recruitment of young polar bears into the population were not affected by the attachment of ear tags or radio tracking collars. Individually identifiable ear tags allow scientists to track growth patterns, changes in condition, and reproductive patterns whenever bears are recaptured. Radio collars, which are linked to satellites, allow scientists to follow year-round movements, to find denning locations, and to monitor the survival of cubs. 

Steven Amstrup, PBI's chief scientist, who is an author on the new study said, "Much of what we know about polar bears today we know because of long-term capture and recapture studies. Individual identification from ear tags, along with measurements and samples taken when the bears were captured, allowed us to understand how the sex and age structure of the population improved as polar bears recovered from excessive harvests in the 1950s and 1960s. Continuing capture studies have allowed us to see those positive changes being reversed, and to determine that physical condition and survival are declining, as global warming has reduced the availability of sea ice habitat."

"We always have felt it was important to assure that our efforts did not harm the animals. This study confirms those efforts are successful and that ongoing and new studies, which are ever more important to understand impacts of continuing declines in vital sea ice habitats, will not harm the bears as we gain that understanding," Amstrup said.   

Read more: USGS Newsroom, New Scientific Study Supports that Capture-based Research is Safe for Polar Bears

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