PACIFIC GREY WHALES IN DECLINE ?

[Anonymous]

Pacific whale decline ‘a mystery’
Grey whales in the eastern Pacific appear to be in some trouble, with the cause far from clear, scientists say.
Researchers
with the conservation group Earthwatch found that whales are arriving
in their breeding grounds off the Mexican coast malnourished.The same
thing happened just after the 1997/8 El Nino event, which warmed the
waters and depleted food stocks.Scientists are not sure whether the
current decline is climate related or part of a natural predator-prey
cycle.”We’re not really sure what is going on now,” said William
Megill, a member of the Earthwatch team who also holds posts at Bath
University in the UK and the University of British Columbia in
Canada.”We certainly saw in Mexico this winter a very large number of
starving whales,” he told the BBC News website. “There is currently an
El Nino building, and this is a worry.”

No fat
There are
thought to be between 15,000 and 18,000 grey whales in the eastern
Pacific, a population that has been in generally good health since
pulling back from the brink of extinction when hunting stopped in the
1940s.

Numbers may be higher now than before the hunting era.
It may be a lot more serious than just grey whales – they may just be the early warning sign of changes for the whole Pacific,
William Megill

By
contrast, the other population, on the western side of the Pacific near
Russia, has been in trouble for many years owing to a combination of
hunting and, latterly, oil and gas exploration. It may now number as
few as 120 individuals.On the eastern side, whales migrate between
their summer feeding grounds to the north, which stretch from the
waters near Seattle and Vancouver to the Arctic Bering Sea, and their
winter breeding home along Mexico’s Baja peninsula.This is one of the
longest migrations of any marine mammal; and at the end of it, in the
last few years, Dr Megill’s team has found the animals arriving thin
and exhausted.”The animals are starving, their fat has just gone, and
there’s not a lot of breeding going on,” he related.”They seem to spend
their time looking around for food when they should be breeding.”

Going down
The
cause of this change is not clear. A link with climatic conditions
makes sense; warmer waters hold less oxygen, they become less
productive, resulting in less of the tiny crustaceans which are the
grey whales’ favoured food.

This is thought to have caused the slump which followed the 1997/8 El Nino event.
One
suggestion, from Dr Justin Cooke, who works with the World Conservation
Union (IUCN) on cetacean issues, is that the greys have just become too
plentiful.”No whale population can expand indefinitely,” he said, “and
these whales seem to have exceeded their historical level so it would
be surprising if they continued increasing – they’re due for a
slump.”When whale numbers were lower there was enough to go round in
poor years, but now numbers are higher and so there’s only enough to go
round in good years.”William Megill acknowledges that the population
could have become unsustainably high.”Around the year 2000, colleagues
looked for mysids (tiny crustaceans) in kelp beds off the Canadian
coast, and they found lots of them,” he said.”The last two years, we’ve
stuck cameras down there and seen nothing.”It could just be the whales
ate them all, and what we’re seeing is the same thing that happens to
wolf and lynx populations when they eat too much of their prey.”But he
is concerned that other factors may be involved too, in particular the
slow rise in the average temperature of the oceans.The deepening annual
Arctic melt, too, would also deprive the whales of a rich source of
food, which accumulates along the edge of the pack ice.”I’m looking at
it and thinking, ‘I’m a bit worried about it’,” he said, “and what we
need to know is what’s going on quickly so we can get proper management
plans in place.”It may be a lot more serious than just grey whales –
they may just be the early warning sign of changes for the whole
Pacific, and we urgently need to know what’s going on.” 

[Author]

May 2, 2007 at 12:14 PM