Whale of a difference in population estimates

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http://straitstimes.asia1.com.sg/techscience/story/0,4386,201719,00.html?

 

JULY 26, 2003 SAT

Whale of a difference in population estimates

 

Genetic study says several hundred thousand more

whales once lived in North Atlantic than thought now

 

SCIENTISTS may have profoundly underestimated the

number of whales that once lived in the North Atlantic

Ocean, a controversial finding that could have

critical implications for the future of whale

conservation, a new genetic study concludes.

 

The gulf between the new estimates and those from

historical statistical studies is so vast - a

difference of several hundred thousand animals - that

it has already provoked a spirited debate over

scientists' techniques in gathering and analysing the

data.

 

'We're suggesting that the oceans can support these

populations in the long term and, in fact, did,' said

geneticist Joe Roman, a Harvard University graduate

student and co-author of the new study with Stanford

biologist Stephen Palumbi.

 

'There are different views on this, and we knew it was

going to be controversial, but this is what the data

show.'

 

Dr Roman and Dr Palumbi analysed DNA from three

species of North Atlantic whales and found the genetic

variation to be unexpectedly high in all cases - a

result indicating that before commercial whaling began

in the 17th and 18th centuries, there was a much

larger pool of animals than historical records

suggest.

 

In fact, the authors reported yesterday in the journal

Science that their analysis showed the pre-whaling, or

'historical', population of humpback whales in the

North Atlantic was 240,000 - 12 times that of the

current estimates of 20,000. There are about 10,000

such whales now.

 

The researchers estimated the historical population of

fin whales at 360,000, nine times that of historical

statistical estimates of 40,000, and the population of

minke whales at 265,000, versus estimates of 100,000.

 

The findings could play an important role in decisions

of the International Whaling Commission, the 51-nation

convention that imposed an international moratorium on

whaling in 1985 to allow stocks to rebuild after their

decimation in the 19th and 20th centuries.

 

The commission has agreed that whaling should not be

allowed until stocks reach at least 54 per cent of

historical levels.

 

The current North Atlantic humpback population is

about 50 per cent of historical statistical estimates,

while fins, at 56,000, and minkes, at 149,000, have

already exceeded the threshold.

 

But under the new genetics-based estimates, only the

minkes are close to 54 per cent. 'One of the things

that the data tells us is that we have a long way to

go for recovery,' Dr Roman said.

 

Commission secretary Nicola Grandy did not comment on

the new study, but noted that 'a majority of our

members currently don't want to see a return to

commercial whaling'.

 

The commission has based its estimates of historic

populations on statistical analyses derived from

whaling records and logbooks.

 

Already, experts are disputing the figures. 'If they'd

come up with numbers that said twice as many, then

maybe we'd start thinking about our methods,' said

mathematician and fisheries specialist Doug

Butterworth of South Africa's University of Capetown.

 

'But when they come up with five to 10 times as many,

then maybe they ought to take another look.' -- LAT-WP