Narwhal numbers good news for Arctic watchers


By Randy Boswell, Canwest News ServiceApril 8, 2010

A Canadian-led team of scientists has supplied a rare piece of good news about Arctic wildlife after developing a new system for counting narwhals that doubles the estimated population of the spiral-tusked marine mammal in Canada’s northeastern waters.

The revised count is particularly encouraging because the narwhal — inspiration for the ancient unicorn myth — was recently identified in an international study as the animal most vulnerable to the impacts of retreating Arctic sea ice, a phenomenon generally viewed as deadliest for polar bears.

Previous population estimates in the Canadian sounds and inlets at the north end of Baffin Island pegged the number of narwhals at no more than 30,000. The latest inventory — which employed a combination of aerial surveys, tracking of tagged animals and new methods for more accurately estimating the number of unseen, diving whales — raises the total estimate to 60,000.

“The narwhal population in the Canadian High Arctic is distributed broadly in summer, and numbers are larger than was previously thought,” concludes the study, published in the scholarly journal Arctic.

“The results, although imprecise, do show that there is a large population out there, one that can probably sustain a large hunt.”

The project’s lead researcher, federal Fisheries and Oceans scientist Pierre Richard, co-authored the study with five other experts from Canada, the U.S. and Greenland.

The study notes that in 2004, Canada’s committee on endangered wildlife recommended listing the narwhal as a “species of special concern” because of “uncertainty about its numbers, trends, life history parameters and levels of sustainable hunting.”

In 2008, a major international study identified the narwhal as the species most susceptible to impacts from the retreat and thinning of Arctic sea ice because of its reliance on specific ice conditions for various behaviours and its specialization in feeding on halibut.

“Since it’s so restricted to the migration routes it takes, it’s restricted to what it eats, it makes it more vulnerable to the loss of those things,” lead researcher Kristin Laidre, a biologists at the University of Washington, said at the time.

Although the narwhal’s unique tusk has fascinated cultures in the world’s polar region for centuries, scientists have only begun unravelling some of the mysteries surrounding the creature.

In 2005, a team of U.S. researchers discovered that the narwhal’s tusk — actually an elongated tooth that can reach up to 2.7 metres in length — contains millions of nerve pathways that are used as a sensory organ for “detecting changes in temperature, pressure, salinity and other factors that may help a narwhal survive its Arctic environment.”

© Copyright (c) Canwest News Service
Original article here

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