Recovering ... but rising populations of some animals, including walruses, have not returned to historical levels.

Recovering ... but rising populations of some animals, including walruses, have not returned to historical levels. Photo: Reuters

MONTREAL: The populations of Arctic marine mammals and fish are rising, a report by the Arctic Council's biodiversity working group at a Montreal conference says.

Fish populations have risen dramatically, the findings of the Circumpolar Biodiversity Monitoring Program, the Zoological Society of London, and the World Wildlife Fund show.

The three organisations collaborated on the analysis, looking at 890 populations of 323 species of Arctic vertebrates.

They said in a statement on Monday that the Arctic wildlife population changes are linked to ''Arctic climate oscillations and changes in commercial harvest'' in neighbouring waters.

The report identified that fish living close to the surface - including such commercially important species as Pacific herring, ocean perch and Arctic cisco - as opposed to fish living near the ocean bottom, were most susceptible to climate change.

Some mammals were found to be recovering from exploitation, but rising populations of grey whales, bowhead whales and Greenlandic walruses had not returned to historical levels.

The sea ice species ringed seal, beluga whale, and thick-billed Guillemot, meanwhile, had declined.

As well, marine birds continued a slow and steady decline that started in the late 20th century. The report said this ''may be related to changes in climate, sea ice and food availability'' and may be the beginning of a longer-term decline.

The effects of Arctic warming also were not restricted to the far north. The Atlantic Ocean was experiencing a decline in vertebrates thought to be driven by Arctic climate shifts, as well as commercial fishing.

In contrast, the Pacific Ocean had experienced a dramatic increase in vertebrates, amid warmer sea temperatures.

Agence France-Presse