Mammals, birds and fish living in the High Arctic experienced an average 26 percent drop in their populations between 1970 and 2004 due to the loss of sea ice, according to a new report from The Arctic Species Trend Index, "Tracking Trends in Arctic Wildlife."

The 2010 report, commissioned and coordinated by the Whitehorse, Yukon–based Circumpolar Biodiversity Monitoring Program (CBMP), was presented Wednesday at the State of the Arctic Conference in Miami. It covers 965 populations of 365 species, representing 35 percent of all known vertebrate species found in the Arctic.

The Arctic region is broken into three floristic zones (High, Low and Sub Arctic), referring to the amount of plant life that exists within the regions' boundaries.

Outside of the High Arctic, the news wasn't all bad: The study found that Low Arctic species populations increased 46 percent between 1970 and 2004 (aided by several conservation efforts, such as tighter restrictions on hunting bowhead whales), whereas Sub Arctic populations remained stable during that time period.

Among the specific findings: Low Arctic fish species such as pollack have benefited from rising ocean temperatures, which is why their populations have increased. Populations of lemmings, caribou and red knot (a shorebird) have all decreased. Migratory birds that pass through the Arctic have decreased an average of 6 percent, although that number is skewed by a "dramatic increase" in some populations of migratory geese.Furthermore, brown bear populations have dropped as much as 50 percent in the last 15 years.

The report avoids direct mention of polar bear populations, but notes that the greatest losses in Arctic sea ice on which the polar bear relies occurred in 2008 and 2009, outside the range of this study.

The CBMP is now calling for increased efforts to count and catalogue Arctic species because many, especially those in the High Arctic, lack detailed population indices.

Image: Arctic region by Andrew Smith. Via Stock.xchng