Finless porpoises in China on brink of extinction

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Finless porpoises in China on brink of extinction

Page last updated at 08:07 GMT, Tuesday, 29 June 2010 09:07 UK

By Matt

Editor, Earth News

Finless porpoises, a rare type of toothed whale, may be even more endangered

than previously thought.

A survey of finless porpoises in Asia has revealed there are two species, not

one, and that they rarely intermingle.

More worrying, finless porpoises living in the freshwater of China's Yangtze

river are genetically unique, say scientists, who warn that greater efforts must

be made to prevent these animals, numbering fewer than 1000, from following

another Yangtze cetacean, the Baiji, to extinction.

Special populations

Finless porpoises (Neophocaena phocaenoides) inhabit a wide range of tropical

and temperate waters around the Indo-Pacific region.

For a long time, zoologists have noted how these porpoises appear to differ

depending on where they live.

Those living around China, for example, have a few different morphological

characteristics depending whether they live in the Yellow Sea, South China Sea

or up the Yangtze river, which holds fresh rather than seawater.

But a new study published in the journal Marine Biology has revealed just how

distinct each population of finless porpoise is, with significant implications

for their conservation and survival.

" The most surprising finding of this study is that the Yangtze finless porpoise

represents a distinct genetic grouping, which is distinct from marine

porpoises, " says Professor Guang Yang of Nanjing Normal University in China, who

conducted the study with Professor Bruford of Cardiff University, UK and

colleagues at Nanjing.

Conservationists currently consider all finless porpoises to be the same

species.

But Prof Yang and Prof Bruford's team analysed the genes of 125 finless dolphins

living around China, including in the Yellow and South China Sea and Yangtze

river.

And the results suggest that special regard should be given to the freshwater

porpoises, which should be managed and conserved separately, they say.

" The freshwater nature of this population makes it unique, " says Prof Yang.

The " jury is still out " on whether the Yangtze finless porpoise should be

granted species status, as more data is required, say the scientists.

But it is so genetically unique, and rare, that special efforts should be made

immediately to protect it.

1,000 and counting

" The most recent field survey conducted in 2006 suggested that there were around

1,000 individuals in the Yangtze River, " says Prof Yang.

" This is much smaller than previous estimates, suggesting a significant

population decline in the past two decades. "

China is already considering upgrading the conservation status of the Yangtze

population of finless porpoises, from a national II conservation grade to

national I.

However, " at least in China, most conservation biologists and cetologists have a

strong feeling that the Yangtze finless porpoise has a very high risk of

extinction, and is very likely to follow the Baiji to extinction within a

short-term period unless conservation measures are put in place, " says Prof

Yang.

The Yangtze River holds the dubious distinction of being the site of the first

recorded extinction of a cetacean (whale, dolphins and porpoises) since records

began.

In 2007, conservationists declared extinct the Baiji (Lipotes vexillifer), a

species of river dolphin endemic to the Yangtze River, after repeated surveys

over many years failed to sight a single animal.

Development, industry, pollution, overfishing and the commercial use of the

river by boats have all been blamed for contributing to the Baiji's demise.

No gene flow

The scientists' survey also revealed that finless porpoises living in the sea

should be considered two separate species.

Those porpoises living in the Yellow Sea are distinct from those in the South

China Sea.

The genetic data showed there is no or very little gene flow between these two

species, even in areas where they overlap.

Therefore each marine population should be conserved separately, warn the

scientists.