Wildlife Declines Observed Across Arctic Region

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Arctic caribouA new international study of Arctic wildlife suggests that climate change and overharvesting are causing many species to dwindle, although some populations in less affected Arctic regions are rebounding after years of protection efforts.

The Arctic Species Trend Index, released on Wednesday, found a 26-percent decline in vertebrates across the High Arctic, the most northerly polar region, from 1970 through 2004. Species in the Low Arctic, a predominantly marine region, increased by an average of 46 percent during the same period. The Sub Arctic, the area most accessible to human development, is home to 3 percent fewer species, according to the report commissioned by the Circumpolar Biodiversity Monitoring Program, an international scientist network organized by the eight Arctic countries.   

While changes in wildlife populations are often due to natural cycles, the Arctic is also experiencing impacts from human-caused pollution - such as warmer average temperatures, reduced sea-ice extent, and high concentrations of persistent toxic chemicals - in addition to unsustainable rates of fishing and hunting. "Human-induced changes in Arctic ecosystems are already resulting in winners and losers [among Arctic species]," the report authors wrote.

North American and Eurasian caribou populations, for example, have declined by about a third from their peak of 5.6 million during the early 2000s. In the Taimyr region of Russia, recent caribou declines may be the result of natural cycles, but climate change is creating patterns of heavier snowfall and earlier ice thaw that may further reduce herd sizes.

More than half of the world's shorebirds breed in the Arctic, so threats to the polar region could alter wildlife worldwide, said report lead author Louise McRae, a research assistant at the Zoological Society of London. "Migratory Arctic species such as brent goose, dunlin, and turnstone are regular visitors to the UK's shores," McRae said in a statement. "We need to sit up and take notice of what's happening in other parts of the world if we want to continue to experience a diversity of wildlife on our own doorstep."

Meanwhile, some species are benefiting from global and regional efforts to strengthen hunting and fishing controls. Bowhead whale populations in the Low Arctic, for example, have climbed nearly every year since a 1982 international moratorium on commercial whaling.

If climate change worsens, as predicted, many of the Arctic's species could be at risk regardless of whether populations are currently threatened. Arctic species are expected to be displaced as more southerly species encroach into warmer northern habitats. In addition, polar ice melt threatens to further shrink Arctic habitats: in September 2009, the sea-ice extent was only 5.1 million square kilometers, the third-lowest coverage in 30 years and only 1 million square kilometers greater than 2007's record low.

The index tracked 965 populations of 306 different species, representing 35 percent of known Arctic vertebrate species. Birds and mammals were the best studied, but report authors acknowledge that the index did a "poor" job of accounting for fish populations. They also concede that the study timeframe may not provide the most accurate picture of changing habitats: if older data had been included, recoveries observed among some species, especially marine mammals, would be "dwarfed" by extensive declines that occured in the early-to-mid 20th century.

Ben Block is a staff writer with the Worldwatch Institute. He can be reached at bblock@worldwatch.org.

For permission to republish this article, please contact Juli Diamond at jdiamond@worldwatch.org.