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| Young Finless Porpoise Highlights Plight of Rare Mammals |
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The 4-month old porpoise frequently sticks his head out of the water to look around the pool at Baiji Dolphinarium in Wuhan, capital of central China's Hubei Province.
The young porpoise, now measuring 80 centimeters, swims neck to neck with his mother named Xiaoci, who is about 7 years old, in the largest pool at the dolphinarium.
His father Daxiong, about 9 years old, lives in a neighboring but smaller pool.
Researchers found Daxiong and a female porpoise named Daxi in the Yangtze River in 1996 and put them together. But somehow they didn't breed.
When a younger female porpoise joined the family in late 1999, researchers separated them in different pools and then reunited them, which seemed to have increased their feelings for each other.
After 11 months of pregnancy, Xiaoci finally gave birth to the little porpoise on July 5. The young porpoise had gained the whole world's attention as he is the first Yangtze finless porpoise calf in the world to be born in captivity.
The success by researchers from the Institute of Hydrobiology under the Chinese Academy of Sciences in Wuhan will not only greatly expand the researchers' knowledge about the reproductive biology of this mammal, but also make it possible to establish a sustainable captive colony of the river dolphin species.
The finless porpoise is a grey small toothed whale species endemic to eastern and southern Asia. As its sole freshwater subspecies, the Yangtze finless porpoise lives only in the middle and lower reaches of the Yangtze River and the attached Poyang and Dongting lakes.
"We will not have the sad story of the Baiji repeated on the Yangtze finless porpoise," said Wei Zhuo, a research fellow with the Institute of Hydrobiology.
Baiji, also known as the Yangtze River dolphin, is the rarest and most endangered cetacean in the world. It's been considered the "Goddess of the Yangtze." However, the latest survey in 1994 showed that no more than 100 Baiji had survived. Now 11 years have passed and that number has continued to dwindle, according to the researchers.
Last year, only two were seen by fishermen in the Honghu Lake in Hubei Province.
Comparatively, the population of Yangtze finless porpoises is larger, but its number has also been steadily decreasing during the past several decades. Before 1991, its population was about 2,700, but researchers estimate that only a little more than 1,000 still roam the waters today. The annual rate of decrease is 7.3 percent.
"The longer we study the species, the fewer they are. We researchers have developed a sad feeling for it," said Wei, who has been studying Yangtze River dolphins for more than 20 years and is a witness to such a dramatic decline of the two species.
The Yangtze finless porpoise is victim to many of the same threats that affect the Baiji as they share similar biological habits.
According to Wei, the most serious threats come from increased human activities accompanying the thriving economy along the Yangtze River, such as illegal and over-fishing, pollution, transportation and dam construction.
Rolling hook, a long line equipped with many sharp hooks to catch fish, can directly kill the porpoises. A study by the institute's researchers reported that illegal fishing accounted for approximately half of the Baiji deaths of known causes.
Moreover, over-fishing in the Yangtze River has seriously depleted fishing resources, leading to a shortage in the necessary food supply, and hindering the development of both the Baiji and the porpoise.
Although the effects of pollution are not well-documented, the growing presence of pollution in the Yangtze River adds serious concerns. For example, in 2004, six porpoises died in Dongting Lake between April and June due to the abuse of a chemical pesticide to control snail fever, a parasitic disease that attacks the blood and liver in humans.
In addition, dams block access to tributaries and lakes where the finless porpoises once fed and nurtured their young. The deafening noise generated by boat engines also contributes to many incidental porpoise deaths as the roaring can confuse the animals, preventing them from navigating and avoiding fatal collisions with propellers.
Relocation measures
To save this unique animal from extinction, researchers proposed and carried out three measures: on-the-spot conservation, relocation conservation, and intensifying research on breeding in captivity in the 1980s.
The successful birth of the Yangtze finless porpoise confirms that it is possible to breed the Yangtze finless porpoise in captivity.
"Hopefully, we can recover the wild population of both the Baiji and the porpoise by a careful release of the captive population," Wei said.
But at present, the breeding techniques for the porpoise in captivity are still quite immature. Preventing the miscarriage and finding the influencing factors for successful mating demand further studies and observations.
As the human population in the Yangtze continues to grow and the pressures facing the river ecosystem increase, it is clear that there is very little hope for the survival of the dolphins in the river, according to the researchers.
Nowadays, they have reached a consensus that the only chance to save the species from extinction will be to relocate all of the surviving dolphins from the Yangtze into the Baiji Semi-natural Reserve, created in 1992 and situated in Tian'ezhou oxbow in the province's Shishou city.
Following the nature reserve's founding, several groups of Yangtze finless porpoise were relocated from the Yangtze River's main waters into the reserve. As a result of careful management of the reserve, the Yangtze finless porpoises not only survive, but also naturally and successfully reproduce in the area.
Around two babies are born each year, which makes the population here capable of self-reproduction and expansion. There are currently about 25 porpoises living in the area.
"This effort represents the world's first successful attempt of habitat relocation for the preservation of cetacean species," Wei said.
He believes that captive breeding and relocation into the reserves could at least guarantee the survival of the species.
However, the relocation may be too late for the Baiji, as it has proven very difficult to find and capture the species in the past.
"It is similar to fishing for a needle in the ocean. At present there is no sufficient funds to support the program," Wei said. "If nothing is done, we could only see the 'Goddess of the Yangtze' gradually going extinct."
(China Daily November 3, 2005) |
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