In this 2020 photo photo provided by Michigan Technological University, one of twenty-five moose that were collared during the 62nd year of the Michigan Technological University Winter Study of Isle Royale National Park is seen on Isle Royale, Mich. In an annual report released Monday, Sept. 14 researchers with Michigan Technological University said they achieved a primary goal of a reintroduction initiative by reducing the park's moose herd, which has become too big for its own good. (Sarah Hoy/Michigan Technological University via AP)

BISMARCK, N.D. (AP) — Federal officials on Tuesday denied extending protections under the Endangered Species Act to a subspecies of moose that historically appeared in four upper Midwestern states.

The U.S. Fish and Wildlife Service ruled “the northwestern subspecies” of moose historically found in North Dakota, Wisconsin, Minnesota and Michigan is stable. Further, the agency said there was no notable biological or other differences with similar moose across the border in Canada, where the population is healthy.

“We have to find those moose are distinct from other moose in the same region and we could not find that,” agency spokeswoman Georgia Parham said.

Two environmental groups filed a petition in 2016 asking for the designation after moose in Minnesota — which has the region’s largest population of the subspecies — suffered a steep decline in the decade prior.

‘We’re pretty shocked,” said Collette Adkins, a biologist and attorney with the Center for Biological Diversity, which filed the petition with another group, Honor the Earth. Adkins said here group may appeal the decision, or file a new one.

Listing the moose under the act would make it illegal to hunt them and could produce habitat protections and federally funded research.

Only North Dakota allows hunting the moose at present. Moose hunting is not allowed in the other three states; Minnesota discontinued it in 2012.

Adkins worried without federal protections, “other states could change course and allow hunting.”

An aerial survey last winter of Minnesota’s moose population showed that the animal’s numbers have remained relatively stable for the ninth consecutive year but still down more than 50 percent since 2006.

The Department of Natural Resources estimated the moose population to be 3,150 animals, or range between 2,400 and 4,320.

Scientists said the drop-off in the Minnesota population has a number of likely causes, including parasites, disease and wolf predation. The environmental groups also blamed a warming climate.