A government plan to shoot up to 184 wolves from a helicopter to reduce their population and save caribou herds in western Canada drew sharp criticism from conservation groups Friday.

British Columbia said the killings are needed to save herds in the South Selkirk Mountains and South Peace regions of the province from possible extinction due to wolf predation.

The population of the South Selkirk herd, which moves freely between British Columbia and the US states of Washington and Idaho, has declined from 46 caribou in 2009 to 16 last year.

"Evidence points to wolves being the leading cause of mortality," said a government bulletin.

"Ministry staff will aim to remove up to 24 wolves by shooting them from a helicopter before (the) snow melt," it added.

British Columbia along with US state officials, aboriginal groups, the US Forest Service and the US Fish and Wildlife Service have been monitoring the herd.

Four herds in the South Peace region have also suffered steep population declines due in part to wolf predation, it said.

A cull of 120-160 wolves in that region is planned.

Ian McAllister of conservation group Pacific Wild said the killings ignore the root cause of the problem facing caribou, which he said is habitat encroachment by human activities.

"Instead of protecting habitat and restricting snowmobilers and stopping road construction, oil and gas seismic testing that have caused the decline of caribou, the government allowed the number of industries to continue in prime habitat," he told public broadcaster CBC.

The wolves, he said, "are paying the ultimate price."

The government acknowledged that "habitat recovery continues to be an important part of caribou recovery," but added it "cannot address the critical needs of these herds in the short term."

It also noted that traditional hunting and trapping of wolves has failed to reduce their numbers "and may even split up packs and increase predation rates on caribou."