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Sad farewell to a river dolphin but genetics prove the Baiji could have survived

By Dave Armstrong - 19 Jan 2012 8:38:51 GMT
The drowning Baiji princess waits in vain

The pink boto, superficially like a Baiji via Shutterstock

Of all the world's remaining river dolphins, the Baiji or Chinese Lake Dolphin (Lipotes vexillifer) has suffered the most. From the large pink Amazonian Boto (above) - to the charmingly shy blue-grey Baiji (below) seems a big step, but once upon a time, scientists believed them to be quite closely related, despite the geographical disparity. In fact these large-brained, almost-fingered cetaceans have very primitive characteristics that place them almost in the Miocene in terms of whale variability. They are not related to each other, apart from the Indus and Ganges species. These two were obviously connected literally quite recently.

So there was this lonely princess, according to the ancient myths, who refused to marry a rich man. Her father threw her in the Yangste where the mermaid like myth relates she lives to this day, two and a half metres long, very frightened and blind, deafened by propellers which injure her frequently. The Three Gorges Dam project in the Yangste basin is likely to kill off any remaining animals, but it is probably too late. This most endangered of all whales has probably drawn her last Snow White like breath! Dangers that have engulfed this graceful species with a retrousse nose include the river traffic and immense pollution in the lakes and estuary which used to form its niche. It used to ply the river in tiny groups, although too shy to be approached at all.

Feeding was nocturnal to a large extent, throughout a middle several hundred kilometres of the giant river. A male Qi Qi, survived for 22 years in captivity, but the only recent estimate of 13 living individuals was in 1999 (2006 surveys found 0). Draw the graph yourself. From an optimum 400 in 1980; through 100 in 1990, to 13 in 1999. I make it 10% decline pa. And 10% of this princess, every year since 1999 brings us in 2012 to the number 1?

The Baiji (Chinese Lake Dolphin / Yangtze River Dolphin / Changjiang Dolphin / Lipotes vexillifer) little photographed and now functionally extinct

The Baiji (Chinese Lake Dolphin / Yangtze River Dolphin / Changjiang Dolphin / Lipotes vexillifer) little photographed and now functionally extinct; Credit: Copyright © Chinese Academy of Sciences

The College of Life Sciences in Nanjing (on the Yangtse) has produced Shixia Xu, Jianfeng Ju, Xuming Zhou, Lian Wang, Kaiya Zhou, and Guang Yang's superb research, published in the journal PLoS ONE, on what has not caused this demise, they sampled three muscle and 14 skeletal samples from dead specimens, killed, fished accidentally or stranded:

While the aforementioned environmental reasons may have finished off our tragic heroine, this erudite group prove that the genome of the species did not lack variations. It could have pulled itself out of the rut it found itself in, with just that little bit of empathy. Nine very divergent alleles were found in only 17 samples. In an isolated (for 25 million years at least) species this variability is totally unexpected. If only the poor cheetah had this same variability, but the cat species are much too inbred. We hope the other river dolphins have some of the same essential genes. The indications are that intense selection has powered the species' progress for millions of years, only to end in this dismal failure to survive. The fault lies in our species, not in our brave princess-like figure, battling the odds.

Research involved the estuary and 1700 kilometres upstream to Yichang, including Baiji's favoured habitat of Dongting Lake and Poyang Lake. The first large mammal to have been made extinct for 50 years, despite official efforts to help, has been entangled, electrocuted, cut by propellers and blasted by construction work. Parasites even joined in the aggravation, while fragmentation of the small groups means that even if one or two are left unknown in a backwater, they would never be able to meet each other.

The geography of the Yangste kiang. Nanjing University is in the second most northerly city. Yichang is in the far west with the coast to the east. The dots indicate baiji distribution by 1980s inferred from survey data (1979-1981) by Zhou; the squares indicate the remnant habitat of the baiji inferred from 1997 survey data by Zhang et al

Geography of the Yangste kiang. Nanjing University is in the second most northerly city. Yichang is in the far west with the coast to the east. The dots indicate baiji distribution by 1980s inferred from survey data (1979-1981) by Zhou; the squares indicate the remnant habitat of the baiji inferred from 1997 survey data by Zhang et al.. doi:10.1371/journal.pone.0030423.g001; Credit: PLoS ONE

The pathogenic effect of the parasites or other disease may well have caused the variation, as the species battled to survive. On the other hand, thinking negative, there are some endangered species on islands that exhibit variation in similar alleles, but a lack of neutral variation. Other authors have found that there was no contraction in range as the baiji declined in population. This again indicates the fragmentation of the tiny numbers available to breed back and produce more calves. Only one was normally born every two years.

Functional extinction, as they describe her fate, for the princess seems pretty much like the real thing. Those among us who are a sucker for a happy ending are in for a disappointment - unless...

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Topics: Dolphins