MINNEAPOLIS  — The Department of Natural Resources has the authority to deny a permit to a researcher for putting radio collars on black bears in northern Minnesota, an administrative law judge ruled Tuesday, saying his methods raise significant public safety concerns.

The DNR had sufficient cause when it decided to stop renewing Lynn Rogers’ permits last year, wrote Tammy Pust, Minnesota’s chief administrative law judge. Agency officials also ordered him to stop installing winter “den cams” that streamed live video of bear cub births to huge international audiences over the Internet.

Pust said Rogers remains free to study wild bears, feed them, walk with them and talk to them. But she said he can’t collar them or visit their dens without a permit.

Evidence presented at a hearing this year “showed that 15 years of Dr. Rogers’ study activities has significantly contributed to bona fide public safety concerns,” she concluded. Around 50 bears roaming his study area between Tower and Ely are now conditioned by his feeding them and have become habituated to humans to varying degrees, she said. Every expert who testified, except for Rogers, said habituated bears pose a risk to the public, she noted.

Pust also said Rogers had engaged in “unprofessional conduct.” She said he rendered some bears almost tame by training them to expect food rewards in return for tricks, and pointed out that he punched one bear in the face when it lunged at him after it ran out of food.

The judge’s recommendations now go back to the DNR, where Commissioner Tom Landwehr designated Kent Lokkesmoe to make the final decision. Lokkesmoe, manager of a DNR operational services division, has kept himself isolated from the case and will make an independent decision, DNR spokesman Chris Niskanen said. Lokkesmoe is likely to rule by early September, Niskanen said.

Landwehr and other DNR officials testified that Rogers’ practice of hand-feeding bears to gain their trust so he could collar them made them too accustomed to humans. And they questioned the value of his research, saying he wasn’t publishing it in peer-reviewed scientific journals where other scientists and wildlife managers could study it.

Rogers called Tuesday’s ruling “a mixed bag,” taking comfort that Pust said some good things about his research. He said he’ll go to the Minnesota Court of Appeals if the DNR’s final decision also goes against him and questioned how independent Lokkesmoe can be given that Landwehr has taken such a strong stand. He denied again that his methods pose any danger to humans and insisted he makes his work available for the whole world to see.

Pust said DNR could not deny Rogers just because of his failure to publish because that was never a condition of his permits. But she rejected his claims that he doesn’t even need a permit.

The ruling has no direct effect on the North American Bear Center in Ely, a popular tourist attraction that Rogers founded, which has other permits.

Rogers can keep collars on his seven remaining research bears pending a final resolution, Niskanen said.