Whales find Arctic path from Atlantic to Pacific
WHALES ARE blazing a trail ahead of humans through the melting ice floes of the Northwest Passage. Satellite tracking has confirmed that loss of Arctic sea ice is opening up the waterway connecting the Pacific and Atlantic oceans to marine mammals.
A route through the Northwest Passage, providing a valuable short-cut between Europe and Asia, has been the quest of seafarers for centuries. Despite the effects of global warming and Arctic sea ice shrinking at a rate of 8 per cent per decade, the route is still too dangerous for shipping.
The research however shows that the Northwest Passage has already opened up for bowhead whales, which are expert at negotiating ice-bound waters.
Between 2001 and 2010, scientists tagged 180 whales in west Greenland, Alaska and the western Canadian Arctic with satellite-tracking transmitters.
The first evidence that bowhead whales were making progress through the Northwest Passage came in 2002. A 12m (39ft) juvenile from Greenland swam to a western point about a third of the way along the route.
Four years later a 14m (46ft) adult male tagged near Point Barrow, Alaska, was tracked east to a point 800km (497 miles) from the position reached by the Greenland whale.
In August last year, two adult males from west Greenland and Alaska – one 15m (49ft) and the other 17m (56ft) long – entered the Canadian High Arctic sea channels.
Approaching from opposite directions, the whales crossed each other’s paths in the Parry Channel that runs through the Queen Elizabeth Islands archipelago in the Canadian High Arctic.
The scientists, led by Dr Mads Peter Heide-Joergensen from the Greenland Institute of Natural Resources, discussed the findings today in the Royal Society journal Biology Letters.
Sea ice in the Northwest Passage was previously thought to have been a physical barrier separating bowhead whales from the Pacific and Atlantic oceans.
The study showed that whales had found a passage route through two principal Canadian Arctic waterways, Viscount Melville Sound and Parry Channel.
It was likely that currents and tidal movements in summer in Viscount Melville Sound maintained “small channels of open water large enough to be used by bowhead whales for passing through the Canadian High Arctic”.
Recent reductions in sea ice in August had “probably facilitated greater access to the area and will ultimately allow for exchange through the passage”, wrote the researchers.
Assuming that less than 50 per cent ice coverage would allow bowhead whales to traverse the Northwest Passage, the Parry Channel would have been open to whales in 1998, 1999, 2007, 2008 and 2010.
The scientists added: “Given recent rates of sea ice loss, climate change may eliminate geographical divisions between stocks of bowhead whales and open new areas that have not been inhabited by bowhead whales for millennia . . .
“The documented movements of bowhead whales in the Northwest Passage are perhaps an early sign that other marine organisms have begun exchanges between the Pacific and Atlantic oceans across the Arctic.
“Some of these exchanges may be harder to detect than bowhead whales, but the ecological impacts could be more significant should the ice-free Arctic become a dispersion corridor between the two oceans.” – (PA)