The latest count of the largest caribou herd in the Northwest Territories shows it has shrunk to less than a third of the size it was 20 years ago.

The survey shows there are 128,000 barren ground caribou in the Bathurst herd now, compared to 186,000 in 2003 and 472,000 in 1986.

The herd lives in a huge area between Yellowknife and Bathurst Inlet on the Arctic coast, a region where roads and diamonds mines have sprung up in the last couple of decades.

The Bathurst herd does not include the Cape Bathurst herd which lives in the Beaufort Delta region and is also suffering a decline.

Government biologist Bruno Croft, who released the results in Yellowknife Tuesday, said the 2006 Bathurst count is the most accurate done to date.

"We had the weather on our side. We were able to monitor the peak of calving and synchronize the photo census at the right time, so we're pretty confident that we've got good numbers," Croft said.

The 2003 numbers were questioned by aboriginal and sport hunters, who thought the numbers were too low.

Although the herd continues to decline, it is still larger than it was in 1979 when biologists estimated there were only 110,000.