Animal populations are shrinking in the high Arctic, but are slightly increasing in the sub-Arctic regions that cover major swathes of the Yukon.
Fish, bird and mammal populations have dropped 26 per cent in the high Arctic, according to the Arctic Species Trend Index, the first global inventory of the world’s most-northern animals, which was launched last Wednesday in Whitehorse.
The index covers 35 per cent of vertebrates in the Arctic and is poised to become an invaluable tool for governments and scientists trying to measure human impact in the rapidly changing region.
“It’s very similar to a stock market index,” said Michael Gill, one of the index’s authors and the chair of the Circumpolar Biodiversity Monitoring Program that commissioned the index.
“We took 1,000 data sets for various birds, fish and mammals from around the Arctic and ran them to determine, on average, are Arctic species going up, are they stable or are they going down?”
The decline of high-Arctic species timed with a rise in more southerly regions falls in line with climate change predictions, he said. But Gill emphasized the index is not research, but merely a constructive way of presenting data.
“You can’t point your figure at a single phenomena that might drive these things,” he said.
The index for all regions goes up 16 per cent over the 34-year period the data sets cover. That means more populations are going up, on average, rather than going down.
“But that doesn’t tell the whole story,” said Gill.
The 39-page index is chock full of charts that compare the fate of one group of animals against another.
“There’s fish versus birds, region versus region, grazing animals against predators,” he said.
That’s where you really begin to see what’s going on up there.
“The Arctic, though it doesn’t have a high biodiversity of species, tends to have very abundant populations of species and these tend to be cyclic,” said Gill.
Caribou, reindeer and lemmings are all part of this group.
“We see a roughly four-year cycle where (caribou and reindeer) go through periods of growth and decline,” he said.
After looking at more than 46 caribou and reindeer herds, the index found that populations in North America and Eurasia move up and down simultaneously.
“The neat thing about that is that a larger force is affecting reindeer and caribou populations and it’s probably climate,” he said.
“It’s probably the Arctic oscillation.”
Also, the marine index has gone upward. One reason is the recovery of many mammal species, like whales and sea otters, from overharvesting.
Fish species are also climbing, said Gill.
“In the mid-1990s until the mid-2000s, there’s been a bit of a phase shift where temperatures have been warming,” he said. “That’s favoured some fish populations that were measured, such as pollock.”
Most recent information – not included in the index – show Alaskan pollock are actually on the decline, he said.
“But this is, again, somewhat of a natural cycle.”
Yukon species include caribou and various shore birds.
Migratory birds and birds that remain in the region are pretty much stable, said Gill.
“However, there are bird groups that have done extremely well and some haven’t,” he said.
Geese populations have almost doubled from 12.5 million to 21 million in the last 20 years. But that is likely due more to changes in their wintering grounds.
“Whereas shore bird populations have been largely declining,” he said.
Despite covering 302 different species, there are some gaps. The index covers 68 per cent of all bird species in the Arctic, 42 per cent of all mammals, but only 14 per cent of all marine life.
There’s also a bias because more data is being gathered in the southern regions than the high Arctic.
“There is so much data from the East Bering Sea that it’s skewing the results a little bit,” said Gill.
“There’s a 46 increase in that index, but we don’t think that’s an accurate picture of the low Arctic as a whole.”
In the middle zone, the sub-Arctic, there’s a negligible decline of three per cent in animal biodiversity.
The index’s authors are hoping to gather more data sets in the high Arctic to complement the information they have in more southerly regions. That would also shed light on the elusive marine animals.
The biggest source of data was from the Russian Federation, said Gill.
The index, which has some big sponsors in the environmentalism world, is the first attempt to monitor changes in animal life in the Arctic as a whole. The Zoological Society of London, the World Wildlife Fund and the World Conservation Monitoring Centre provided backing for the index. Previously, data on fluctuations in Arctic biodiversity were predictions based on sea-ice changes and climate records.
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