Climate row touches blue whales

Krill: A crustacean at the centre of the Antarctic food web

By BBC News Online's environment correspondent Alex Kirby in Bonn

The survival of the few remaining blue whales in the Antarctic is now imperilled by global warming, conservationists claim.

There is a huge area which can have krill and that is accessible to whales

Keith Reid, Bas

WWF, the global environment network, says rising temperatures are melting the sea ice, the home of the krill, the tiny crustaceans on which the whales depend.

They think the Antarctic ozone "hole" is also worsening the problem. And they want the world to redouble its efforts to tackle climate change.

But the analysis has been criticised by Antarctic scientists who say it oversimplifies and exaggerates some of the changes taking place in the region. They say WWF has used research on localised areas of the White Continent to make more general claims that cannot be supported.

Krill relationship

WWF's claims are contained in a report entitled Blue Whales - Under Threat.

It says the sea ice is a habitat for microscopic algae, which are released when the ice melts in the summer and are then eaten by the krill. Several studies, it says, have shown that rising temperatures are causing the ice to retreat and that food supplies are getting scarcer.

Uncertainty about the science of climate change makes some think Kyoto is a mistake

It highlights a February 2001 study by the British Antarctic Survey (Bas), which found that demand for krill from the different species that depend on it (not only blue whales and other cetaceans, but also seals and penguins) began to draw level with supply during the 1990s.

And they quote one researcher who says the sea ice shrank by about 25% between the mid-1950s and mid-1970s.

The WWF report claims the annual thinning of the ozone layer over the southern oceans is intensifying the threat to the krill. Ozone protects all living things against the Sun's ultraviolet-B radiation, which can cause cancer and damage the immune system.

Sounding the alarm

The report says: "A 1999 study found that even relatively small amounts of UV radiation can cause DNA damage and mortality in krill, especially among juveniles. UV-B radiation may also impact the algae on which krill feed."

WWF says the problem of declining krill threatens most of the Antarctic food chain, but it is especially serious for the blue whales because there are so few of them. They are the largest animals ever to have lived on Earth, and before the onset of commercial whaling they are thought to have numbered about 250,000 in the southern oceans, with perhaps another 50,000 elsewhere.

If we wanted an emblematic species to hang all our hopes on... what better than the blue whale

Stuart Chapman, WWF

Now, WWF says, the Antarctic population is probably fewer than 1,000 animals. It believes the extra stress imposed by pressure on the krill could be enough to drive them to extinction.

Stuart Chapman of WWF told BBC News Online: "The problem is that we know so little about the blue whales, about their age and sex ratios, their feeding behaviour, even their locations.

"So when you get this kind of warning shot that indicates something is going terribly wrong in the Antarctic, we need to sound the alarm. If we wanted an emblematic species to hang all our hopes on, to prod world leaders into action, what better than the blue whale?"

'Leap of faith'

But Keith Reid, from the British Antarctic Survey, an expert on krill and their predators, told BBC News Online that WWF were making statements that the science could not support.

Mr Reid said the relationship between sea-ice retreat, declining krill population and predator survival was based on just the Antarctic peninsular, the only location on the White Continent where any significant warming had been detected. Other areas have shown little if any warming, or changes in ice extent.

Green groups are making a huge effort to influence the Bonn talks

"The work that has been done is based on those predators that breed on land, so the range over which they can get krill is quite restricted. This doesn't affect whales in the same way.

"There is a huge area which can have krill and that is accessible to whales. Penguins and seals, on the other hand, have to come back to land to breed and feed their young."

Mr Reid said there was evidence that the amount of krill available to predators in the Antarctic had declined over the past 20 years, "but determining whether that's because of a reduction in krill or an increase in the number of mouths to feed is very difficult to work out".

Whale meeting

He added: "To take the available evidence and generalise it up to a level of saying that the blue whale's recovery is endangered seems to me to require a fair leap of faith."

WWF has called on the International Whaling Commission (IWC), which holds its annual meeting in London from 23 to 27 July, to fund population surveys and research on blue whales.

It says the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) should enforce highly precautionary catch limits for krill.

And it says industrialised countries should tackle climate change by cutting their carbon dioxide emissions to 10% below their 1990 levels by 2010.

That is roughly twice the reduction proposed in the global climate treaty, the Kyoto Protocol. Attempts to finalise the protocol will come to a head here when ministers from more than 150 signatory countries meet from 19 to 22 July.