ISLE, MINN. — Farmer Dan Lorentz heard the wolves howling this fall, then found the freshly killed calf.

"This is all that's left," he said, pointing to a bone-white rib cage, two legs and some hair from the 700-pound animal killed and consumed in September by wolves in a pasture a stone's throw from his home.

Lorentz, 38, doesn't farm in northern Minnesota -- the state's prime wolf country. He and his wife, Michelle, and three kids live just east of Lake Mille Lacs, less than 100 miles north of the Twin Cities. They've been there 10 years.

"It's our first problem with wolves," he said.

But maybe not his last.

The deadly cat-and-mouse game between livestock owners trying to raise animals and wolves trying to eat them continues as it has since Europeans settled the state. In recent years, more than 100 domestic animals have been killed by wolves annually. And while groups opposing the state's first wolf hunting season beginning Nov. 3, and subsequent hunting and trapping seasons beginning Nov. 24, quarrel with the Department of Natural Resources over the agency's 400-wolf quota, wolves blamed for livestock depredations have been routinely trapped and killed for decades, including a record 266 so far this year.

Evidence: wolf tracks

Trapper Dave Hughley, 56, of nearby Onamia was brought in after conservation officer Scott Fitzgerald determined Lorentz's calf had been killed by wolves.

"There were wolf tracks nearby," Fitzgerald said, pointing to paw prints in a small gravel pit not far away.

Hughley has been trapping furbearers, including coyotes, for 40 years. Only recently was he certified by the state to trap wolves in depredation cases.

"Wolves aren't that easy to catch," he said.

He boils his traps to remove any human scent, and uses rubber gloves to place them. The traps are staked to the ground so a wolf can't run off. The trap jaws are smooth and are meant to grip the animal's foot, not injure it -- the same traps used by researchers who radio-collars wolves.

Since the wolf was protected by the Endangered Species Act in 1974, federal trappers quietly have been removing problem wolves from farms. But the situation changed this year when the wolf was delisted and the state assumed its management, and also the responsibility of handling the depredation complaints.

Now about 80 certified trappers like Hughley have joined the ranks of the dozen federal trappers who still handle most depredation complaints. Of the 266 wolves killed this year because of depredation, federal trappers took 214, state trappers 37 and individuals 15.

Eighteen days after Hughley set 10 traps on Lorentz's farm, he caught and then shot a 100-pound male wolf. Later he trapped a female wolf, and he has since removed his traps. He was paid $150 for each by the state.

Because wolves were responsible for Lorentz's lost calf, valued at about $1,000, he was compensated by the state Department of Agriculture. For the 2012 fiscal year ending June 30, the department paid a record $154,000 for 111 claims.

Impact to wolf population

The DNR doesn't believe the killing of up to 700 wolves this year -- which would include 400 allotted in the hunting and trapping seasons and those killed in depredation cases -- will hurt the wolf population, estimated at 3,000.

Critics of the hunt disagree.

"For them to say this season will have no impact ... it's a level of naiveté that I find arrogant," said Maureen Hackett, founder of Howling for Wolves, a group that has sued to stop the wolf hunting and trapping season. "They cannot predict, and they are taking a risk they shouldn't be taking."

John Hart, 46, wildlife biologist with the U.S. Department of Agriculture's Wildlife Services, has been trapping Minnesota wolves for 20 years as head of the federal depredation program.

"The wolf is highly intelligent and highly adaptive and a survivor," he said. "I know there are some people concerned. But I'm confident the [state] management plan will assure a healthy wolf population in the future."

Dan Stark, DNR wolf specialist, agrees.

"I don't think we'll see much difference in the wolf population. Our 400-wolf quota [for 6,000 licensed hunters and trappers] takes into consideration the wolves dying from depredation control, poaching and vehicle kills."

Removing about 700 wolves would be about 23 percent of the population. Stark said biologists have determined that about 30 percent could be killed without hurting the population.

The often-cited 3,000-wolf figure is a wintertime estimate, said Stark. The wolf population is continually changing over the year, he said, adding that the population may jump to 5,000 in the spring when pups are born.

"Then it declines throughout the year because of mortality factors," he said.

Wolves killed to control depredations, and those killed by hunters and trappers in the controversial new season, will include wolves that would have died from other causes, Stark said -- a concept known to biologists as compensatory mortality.

"The population is based on reproduction and mortality, not just mortality," Stark said. Other wolves will fill the population gap left by those that are killed, he said.

Hunt won't affect complaints

Hackett counters that the killing of more than 260 wolves this year for the loss of 90 to 100 cattle and sheep is an overreaction.

"There is no evidence lethal control works, or hunting works. There's supposedly 265,000 cattle in the wolf range, and they lose 90 to wolves," she said. "That's not very many."

But, said Stark: "The hunting season wasn't intended to reduce depredation conflicts." That could change in the future if the DNR increases wolf harvest quotas in problem areas, he said.

Hackett agrees farmers should be paid for their losses and should perhaps be allotted a "cost-of-business" payment for operating in wolf country. But she said they also should be encouraged to use nonlethal methods to reduce depredation, including guard dogs, electric fencing, noise devices or flashing lights.

"They'd rather just kill wolves," she said.

She believes the hunting and trapping season will disrupt packs and could actually exacerbate wolf-livestock conflicts.

Waiting ... for wolves

Back at Lorentz's farm, he acknowledged that raising livestock in wolf country carries some risk. "But I expect them deep in the woods, I don't expect them out back of the barn," he said.

"You talk to people here -- no one wants the wolves around. There's getting to be too many."

He was pleased Hughley trapped two from his place, but he has no delusions he's seen the last of them.

"I'm glad they're gone," Lorentz said. "But I know there'll be more."