A national environmental group sued the Minnesota Department of Natural Resources (DNR) on Thursday, reigniting a decade-old fight over animal trapping in northern Minnesota.

The DNR is allowing hunters and trappers to set snares and other traps for small game — such as coyotes, martens and bobcats — but are also capturing and killing the federally protected Canada lynx, the Center for Biological Diversity argues in the lawsuit.

"It's really frustrating that the DNR knows its trapping program is capturing lynx, but it refuses to take a few common sense steps needed to prevent it," said Collette Adkins, senior attorney for the Center for Biological Diversity.

Canada lynx have become incredibly rare in Minnesota, with a population somewhere between 50 and 200 animals, according to the latest assessment from the U.S. Fish and Wildlife Service.

Lynx are about the size of bobcats, with big feet that act like snowshoes allowing them to easily walk over deep snowdrifts. They're native to northern Minnesota and have been given endangered species protections since 2000.

While the lynx are protected from being targeted by hunters, they get caught in snares and foothold traps set up for other animals.

At least 16 lynx have been trapped in Minnesota since 2008, according to the center. At least six of those died.

"One of the most common traps that are catching lynx here are these strangulation sneers, where a cable wire tightens around neck," Adkins said. "The problem with those is they are so indiscriminate as to what gets caught, we would hope the DNR would restrict them in lynx habitat."

The center is asking the court to require the DNR to update its rules to require trappers to install "lynx exclusion devices," that allow smaller animals inside the traps, but keep the wildcats out.

DNR spokesman Steve Carroll said the agency hasn't been served with the lawsuit and declined to comment.

The center sued the DNR over the same issue in 2006.

The judge in that case required the DNR to make several rule changes to make it harder for lynx to get trapped in the snares, including limiting their size and prohibiting types of bait. The court also ordered the DNR to apply for a federal permit — called an incidental take permit — that would potentially include more conditions to minimize accidental lynx deaths.

The DNR adopted the rule changes ordered by the court. But while the DNR applied for the federal permit, it never received it.

The U.S. Fish and Wildlife Service never approved the DNR's application. It wasn't immediately clear why, and a spokesman said Thursday he would look into the issue.

Two DNR officials — David Olfelt, director of the department's fish and wildlife division, and Sherry Enzler, an agency lawyer — blamed the Fish and Wildlife Service for never issuing the permit in a February letter to the Center for Biological Diversity.

The federal agency "has declined to undertake the necessary environmental review … or to otherwise act on DNR's permit application, despite the DNR's repeated requests that it do so," they wrote.

They also defended the regulations put in place after 2008, noting that lynx trappings have dropped overall and that deaths from the traps have fallen "to an average of one deceased lynx every two years."

The lynx population is so low in Minnesota that every animal incidentally taken is a major loss, Adkins said.

Greg Stanley • 612-673-4882