Giant pandas remain an endangered species despite the births of 23 cubs in Chinese zoos over the past two months, a leading panda researcher in southwest China's Sichuan Province said Thursday.

Giant panda still endangered despite baby boom.[File photo]

"The baby boom began in early July, with 23 cubs born in captivity -- 14 at the Wolong research center, eight in Chengdu and one in Beijing," said Zhang Zhihe, director of the Chengdu Research Base of Giant Panda Breeding.

Since the boom, the total number of giant pandas in captivity at zoos worldwide had topped 300, a target Chinese scientists set in 2002, said Zhang.

"It's good news, but the number is still not big enough for the bears to be taken off the endangered list," said Zhang.

China's panda experts believe the 300 pandas in captivity are the minimum viable population for the species to reproduce and sustain in 100 years to come.

To achieve that goal, Zhang and his colleagues have worked to expand the panda population by helping the sex-shy animal breed since the Chengdu base was founded in 1989.

"The growth in the number of artificially-bred pandas, however, was inevitably accompanied by a decline in the quality and genetic diversity, as many captive pandas are blood relations," said Zhang. "This will hinder the species' survival in the long run."

While all the captive-bred pandas were offspring of the 46 wild pandas who were first kept in zoos, he said 61.4 percent of them were offspring of four giant pandas -- Pan Pan and Dong Dong at the Wolong China Giant Panda Protection and Research Center, and Ha Lan and Lin Nan at the Chengdu base.

Pan Pan alone had 107 offspring, said Zhang. "It's hard to avoid inbreeding when so many pandas share the same blood."

Panda researchers have therefore shifted their focus from quantity to quality, he said. "We're no more satisfied with the mere expansion of the species. Rather, we are aiming to improve the quality of the breeding."

Zhang said Chinese zoos had been working to avoid inbreeding by swapping either pandas or their frozen sperm since 2004.

Meanwhile, wild training of zoo pandas has topped the agenda at the Chengdu base and the Wolong center, China's top two panda research bodies, in the hope the bears will eventually return to the wild.