Whales make new friends as warmer seas drive migration

In August 2010, a bowhead whale(left;courtesy NOAA) from the Bering Sea swam into the North-West Passage. Having negotiated Alaska and picked its way through the maze of ice-ridden channels off the north coast of Canada, it made its way to Viscount Melville sound. Viscount Melville Sound is an arm of the Arctic Ocean in Kitikmeot, Nunavut, Canada. Forming part of the Parry Channel, it separates Victoria Island and Prince of Wales Island from the Queen Elizabeth Islands. East of the sound lies Lancaster Sound, leading into Baffin Bay; westward lies the McClure Strait and the Arctic Ocean. Viscount Melville sound is a part of the Northwest Passage. There the bowhead whale met a second bowhead, which had entered the passage from Baffin bay, next to Greenland. (lower right; click to enlarge)

The two met because the passage, long blocked by ice, is opening as the climate warms. The anecdote, which came to light thanks to satellite transmitters on the whales, is part of increasing data showing how ocean life is being transformed by rising sea temperatures, with some bits of apparently good news to sweeten the pill.

The two bowheads were tagged by Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources in Nuuk and his colleagues. Bowheads entered the passage in 2002 and 2006, but this was the first time two were seen to cross paths (Biology Letters, DOI: 10.1098/rsbl.2011.0731).

Heide-Jørgensen thinks whales have been sneaking through, undetected, since the ice began to retreat. The Greenland population, once decimated by whalers, has grown suspiciously fast since 2000, and Heide-Jørgensen suspects the hand of immigration from Alaska.

That's perfectly possible, says Aviad Scheinin of the University of Haifa in Israel. In May 2010, he spotted a Pacific grey whale in the Mediterranean Sea, which probably got there via the Arctic. Conventional wisdom has it that grey whales have been extinct in the Atlantic Ocean for more than 200 years, and the species survives only in the north Pacific. That was the case until the week of May 3, 2011, when a 13-meter-long grey whale was spotted cruising off the coast of Israel.

"This is sensational," Phillip Clapham of the US government's National Marine Mammal Laboratory in Seattle was quoted as saying after hearing the news from marine biologists in Israel. "The most plausible explanation is that it came across an ice-free North-West Passage from the Pacific Ocean, and is now wondering where the hell it is.

"Further evidence of links between Atlantic and Pacific ecosystems comes from Cambridge bay
in Nunavut, Canada, where pods of narwhals appeared on 15 August. They do not normally venture so far west, but shrinking ice seems to be changing that.

It's not just whales that are affected by warming seas (see map below). Steve Simpson at the University of Bristol, UK, looked at 25,612 trawls in fisheries around the UK and in the North Sea between 1980 and 2008. There waters have warmed by 0.05 °C a year since 1980.Populations grew for 27 of the 50
most common fish; nine declined and 14 held steady (Current Biology, DOI: 10.1016/j.cub.2011.08.016). "I had expected to see many struggling and maybe one or two doing well," he says,

In his surveys, cold-adapted species like cod were all in decline, replaced by warm-adapted ones like red gurnard, which breed faster. Markets are catching on. "Five years ago fishermen were selling red gurnard as bait to crab fishermen for 50 pence a fish," Simpson says. Now restaurants buy them for £5 a fish.

But the pill is bitter-sweet. An open North-West Passage may be good news for bowheads, which will have more places to feed, but many Inuit will struggle, since they rely on walruses that are running out of sea ice on which to breed. And although UK fish markets may be boosted, that's no help to fishing communities in the tropics. If temperatures rise dramatically, many species there will either move out or die.

Source:

NewScientist Environment,"Whales make new friends as warmer seas drive migration ", accessed October 3, 2011
NewScientist Environment,"Stray grey whale navigates the North-West Passage", accessed October 3, 2011

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