The Porcupine caribou herd isn't likely to come to the Dempster Highway again this year, says Environment Yukon biologist Mike Suitor.

All indications to this point suggest the herd is going to overwinter somewhere near the Yukon-Alaska border, he said in an interview last week.

"But you know, these are barren land caribou, so anything can happen,” he said.

Suitor said aerial survey work conducted in late October to track 86 radio and 14 satellite collars puts the majority of the herd south of Old Crow, and west of the Dempster.

The Dawson City regional biologist said because the vast majority of the herd is west of the Dempster, hunting was closed last Thursday in subzones 2-16, 2-23, 2-27, 2-28, and 2-29 to protect the Hart River woodland herd.

When the Porcupine comes down to the Dempster and mixes among the Hart River caribou, hunting stays open because the chances of shooting a woodland instead of a barren land Porcupine caribou are much fewer, Suitor explained.

He said when there is no Porcupine caribou around to speak of, any caribou taken would almost certainly be Hart River caribou. The Hart River herd is estimated at 2,200 animals, he said.

Suitor said it is not easy to tell a woodland from a barren land caribou.

In an update this morning using information collected from the 14 satellite collars, Suitor explained the vast majority of the Porcupine herd are still south of Old Crow, and east of the Dempster.

"They are still not too near the highway yet,” he said.

"If the big part of the herd moves down toward the highway, we would have the ability to reassess, but at this time, we are going to keep things closed.”

Following years of concern the Porcupine herd was shrinking to disturbing low levels, the first successful aerial count in 10 years confirmed in 2010 the herd was at a healthy population of 169,000 animals.

Records indicate the last time a significant portion of the Porcupine caribou hit the Dempster Highway was three years ago, in the fall of 2009.

In recent years, it's become more uncertain whether the herd will move toward the Dempster.

Suitor said there really is nothing to explain the shift, other than it's not unusual for barren land caribou to overwinter in different areas.

It's likely people are noticing the shift more now because they grew used to large concentrations of Porcupine caribou moving into the Dempster Highway area to overwinter on a fairly regular basis, he said.

Records indicate migration routes have a direct bearing on harvest levels.

In the fall of 2009 and early winter of 2010, when the caribou did reach the Dempster, licensed Yukon and non-resident hunters harvested 187 animals.

When the herd didn't show up last year in any great numbers, the harvest by licensed Yukon hunters was 13 Porcupine caribou.

Harvest numbers by aboriginal hunters in the Yukon and Northwest Territories were largely unavailable up until 2010 because there was no requirement for aboriginal hunters to report their harvest.

In 2010, aboriginal communities across the Yukon and MacKenzie River Delta signed a new Porcupine Caribou Harvest Agreement.

Under the pact, all hunters are required to report their harvest, and all hunters are encouraged to shoot bulls only to protect the reproductive value of cow caribou.

Figures in years gone by estimated the annual aboriginal harvest at about 4,000 or more animals, with a high of 6,000.

For the first year mandatory reporting was required, harvest information published by the Porcupine Caribou Management Board indicate a total harvest of 1,720 caribou between June 2010 and June 2011.

There is, however, some uncertainty regarding how much of the harvest was actually reported.

Harvest figures for the year from June 2011 to 2012 are still being compiled.

Of the 1,720 caribou taken from June 2010 to June 2011, 265 were reported by aboriginal hunters in Old Crow – 213 bull and 52 cows – and 38 bulls were harvested by licensed Yukon hunters.

The four Gwich'in communities of the MacKenzie River Delta accounted for the largest portion of the harvest, taking 1,197 Porcupine caribou.

No split in the harvest between bulls and cows was made because the harvest of cows was so small, according to the management board's report.