No Porcupine Caribou census this year – again
October 2007
The Porcupine Caribou weren't counted again this year. A census attempt was made this summer but the pictures didn't work out. This is bad news for many people who rely on the herd for food.
Each summer, biologists from the Alaska Department of Fish and Game, the US Fish and Wildlife Service and Government of Yukon have waited for the right conditions to do an aerial survey of the herd. In the best case scenario, the caribou aggregate, or group up, on the coastal plain of the Arctic Refuge in Alaska, and the weather cooperates to ensure clear photos are able to be taken. Since 2001, though, that hasn't happened.
Tara Wertz works as an Arctic National Wildlife Refuge biologist for the US Fish and Wildlife Service. She explained, "The weather has not been cooperative. Typically, the caribou will aggregate on the coastal plain when it's hot and calm because the insects come out and bother them. The coastline offers cool breezes that help keep the mosquitoes away."
This year, again, the weather wasn't ideal and the caribou didn't aggregate on the coastal plain. It gathered closer to nearby mountains instead. "The last few summers, including this one, have been cool and cloudy most of June and the caribou have not been forced to go to the coastline. Instead, they have gone along the foothills and started to move over the Brooks Range soon after they calve," Wertz said.
But so many people have been holding their breath in anticipation of a count. So, it was decided to at least make an attempt to do the photocensus.
"We did the census on a very bright, sunny day. Therefore, the extreme contrast between the brightly lit slopes and the shadows in the valleys made it impossible for the camera to adjust for high quality pictures. The photos themselves were too dark to see the caribou in the shadowed areas," said Wertz.
Dorothy Cooley, Regional Biologist from the Yukon Department of Environment was part of the team who flew to Alaska for the census. She was also disappointed that the mountain shadows compromised the quality of the pictures.
"It was really disappointing, but in the end, the Porcupine Caribou Technical Committee thought it was important that we tried the census, even if the caribou were in the mountains. If we can't rely on caribou forming tight aggregations on the coastal plain, as has been the case for several years now, we need to figure out how we might count the herd if it groups up in the mountains," Cooley said.
She said the technical committee still wanted to try to make the pictures work.
"The people who develop the large format film we use in the special cameras were asked if they could enhance the photos to see if we could see caribou in the shadows. Basically, they said that those shadows look like unexposed film – there is nothing there. So, the technical committee decided not to use the photos because it wouldn't provide an accurate estimate of the herd size," Cooley added.
Traditional harvesters of the herd in the Canadian portion of the range include Fort McPherson, Tsiigehtchic, Inuvik and Tuktoyaktuk in the Northwest Territories, and Old Crow, Dawson and Mayo in the Yukon. There is widespread concern in the communities that the census was not possible again this year.
Billy Archie is the President of the Aklavik Hunters and Trappers Committee. "Getting no census makes me more leery about where the herd is going. I don't like the concept of guesstimating the population. We also aren't sure of the harvest numbers throughout the range. Priority needs to be put on getting harvest data and a number that we can have confidence in based on previous harvest studies."
"I think when you look at scientists, I feel confident with the people we have at hand, like Dorothy Cooley and Don Russell, who have been involved with this for so many years. I have some confidence in their research and what they say the condition of the herd is," said Archie.
Joe Tetlichi, Chair of the Porcupine Caribou Management Board said the board is also disappointed that there was no census. "This concerns the board because getting a count would give the communities some peace of mind. If the population is low, they can look at what actions should be taken," Tetlichi said.
According to scientists, the herd is at a low point in a downward population trend. The herd's population has been recorded to be as high as 178,000 in 1989. However, the size of the herd has decreased each year since then.
Wendy Nixon is a wildlife biologist with the Canadian Wildlife Service. She said, "Historically, barren-ground caribou herds have gone through cycles of increase and decline. Those cycles may be related to food availability, changing weather patterns, and changes in survival and mortality."
Mortality refers to the number of caribou that die for various reasons such as predation, poor nutrition, or other factors.
"The Porcupine Caribou herd increases at a slower rate than other barren-ground herds. That's a problem because it takes longer for the herd to reach its peak," Nixon said.
The last census in 2001 indicated the herd was at 123,000. But, according to biologists, there are other ways to get a good population estimate.
"We have a computer model that considers birth rate, survival rate, and harvest numbers of the herd. The model indicates a population estimate of 110,000 to 112,000 animals currently," Wertz explained.
"After six years, yes, we are disappointed that the count didn't get done again. But there are other indicators that tell us what the population of the herd is and they tell us that the herd is declining," said Tetlichi.
So, for management purposes, that is the number that everyone will hang their hat on.
Tetlichi said another photocensus will be planned again for next summer. It is hoped that the caribou and the weather will be more cooperative then.
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