Polar bear tranquillizers, collars do no lasting harm: study

A newly published study says shooting polar bears with tranquillizer darts, handling them and leaving them with radio
collars doesn't do any lasting harm — even if a bear is captured as many as 10 times.

Despite long-standing concerns from many Inuit and some scientists about the effect on the bears, the U.S. Geological Survey study concludes the animals are moving normally within five days after being picked up.

"These shorter-term, post-capture effects do not appear to have translated into any long-term effects on body condition,
reproduction or cub survival," the study concludes. "Additionally, collaring had no effect on polar bear recovery rates, body condition, reproduction or cub survival." 

Capture studies have long been controversial in the North. 

Some earlier research has suggested using such techniques to study the bears harms them. Inuit hunters say the approach injures the bears, leaves them with chemical residues and shows disrespect to a culturally important animal.

"This intrusive method is not acceptable to the Inuit," said James Eetoolook of Nunavut Tunngavik Inc., which monitors the Nunavut land claim. 

The question has grown in urgency as climate change increases pressure to understand what's happening to bear populations. 

The new study uses data collected from the South Beaufort Sea population, which Canada shares with the United States. It drew its conclusions from the results of 3,800 captures between 1970 and 2013.

"We had a great opportunity to look at the long term to see if any animals are being negatively affected, and we are very pleased to report we couldn't find any evidence like that," said Steve Amstrup, the study's lead author.

Researchers found 90 per cent of the bears reached their previous level of movement and activity within five days of being captured.

Body mass didn't seem to be different between bears that had been captured before and those that were being tranquillized for the first time. That held for bears that had been darted and studied repeatedly, up to 10 times.

Litter size didn't seem to be affected if the mother had been previously captured. Cubs born to previously captured sows were the same size as those born to non-captured moms. Nor was the mama bear's ability to look after her young affected by wearing a radio collar.

As well, attaching radio collars didn't seem to have any different impact than ear tags or glue-on transmitters.

Nunavut Tunngavik skeptical

Eetoolook finds the conclusions "hard to believe." 

Collars, he said, inhibit the bears' movement and make it harder for them to hunt seals through the ice or in open water. Hunters have found dead bears wearing collars, he said. 

Scientists should find a more modern way to study the animals and lean more about Inuit traditional knowledge, Eetoolook suggested.

"The Inuit respect wildlife, so therefore they don't handle wild animals. We're not going to agree to anything that affects the lives of polar bears."

Steve Pinksen of Nunavut's Environment Department said the territory has been moving toward less handling of bears during its research.

Amstrup said aerial surveys only provide a snapshot of bear numbers and don't give any information on the condition of the animals. Genetic analysis of hair samples can yield valuable data — as long as the samples are uncontaminated, from single individuals and collected over a long enough period.

"By capturing animals, over time, you get an opportunity to learn the details of the sex and age composition, the health of the animals, the changes in the animal's growth over time, whether or not they reproduce and how many times," Amstrup said. "All those things you simply can't get by any other method."