African elephants could eventually become extinct because they are being killed at a rate not seen since an international convention banning ivory trade almost two decades ago.

	African elephants are hunted for their valuable ivory

The problem is now so acute - with more than 23,000 slaughtered in a single year - that conservationists are urging Western nations to renew their efforts which all but halted the black market trade of ivory after the ban was first enacted in 1989.

The continued loss of elephants, which is about to exceed the pre-ban slaughter, will have serious consequences, said Prof Samuel Wasser, director of the University of Washington Centre for Conservation Biology and lead author of a paper published today detailing how DNA detective work can reveal the location of the poaching.

"We have to act now, before it is too late," Prof Wasser said. "Elephants are majestic animals and are not trivial to the ecosystem. They are a keystone species and taking them out significantly alters the habitat. It has ripple effects on lots of different species."

For the year ending in August 2006, authorities seized nearly 24 tons of contraband ivory, Prof Wasser added. But given that customs agents typically detect only about 10 per cent of black market activity, this snapshot of the slaughter is equivalent to ten times as much, or more than 23,000 elephants - equivalent to around seven per cent of Africa's total population.

In 1989 a kilogram of high-quality ivory sold for $100 (around £50) on the black market. That rose to $200 in 2004 but by last year had ballooned to $750 (around £375) per kilogram.

China's and Japan's burgeoning economies are a major forces driving the trade, attracting organized crime, Prof Wasser said. "If it really is organised crime that's driving this, then the only hope we have of stopping it is to stop the ivory at the source, to not let it into the international market. Because once it's in the international market, the trade is very hard to stop."

His team used DNA analysis to trace the geographic origin of the poached ivory found in the largest illegal ivory seizure since the international trade ban, a set of 532 tusks from a June 2002 seizure of over 6.5 tons of ivory in Singapore.

The contraband ivory bound for the Far East from Malawi represented ivory from 3,000 to 6,500 poached elephants. The tusks weighed an average of 11 kilograms apiece, more than twice the weight normally seen in the market, indicating they came from a large number of older elephants.

The shipment also contained 42,000 hankos, small blocks of solid ivory used to make signature stamps, or chops, that are widely used in the Far East.

Authorities assumed the ivory had been collected from many different places, especially from forest elephants. However, comparing their samples with DNA taken from elephant tissue and faeces at sites across Africa, the researchers found that the seized ivory likely originated from the savannah in an east-west band centred in Zambia.

Law enforcement agencies have identified many participants in the poaching, yet not one person has been prosecuted, Prof Wasser said.

He added that shortly before the seizure, Zambia had petitioned for permission to sell its ivory stockpiles internationally, stockpiles that were supposed to have existed before the international ban took effect in 1989. But the application said only 135 elephants were known to have been killed illegally in Zambia in the previous decade "woefully shy of the 3,000 - 6,500 elephants we estimate to have been killed in Zambia surrounding the seizure, let alone during that entire 10-year period".

Subsequent to being informed of Prof Wasser's findings, the Zambian government replaced its director of wildlife and began imposing significantly harsher sentences for convicted ivory traffickers in its courts. "However, one still has to wonder whether this will be enough."

Expecting a poor nation such as Zambia to resist the ivory racketeers and curb the illegal trade on its own was unrealistic, said the scientists and they argue that Western nations must resume efforts to halt ivory trafficking.

They note that the west contributed heavily to enforcement efforts when the international ban took effect in 1989, and in the next four years poaching was virtually eliminated.

But the success apparently left a sense that the problem was solved and the nations largely withdrew their funding by 1993.

Prof Wasser and colleagues want to see reinstatement of strong enforcement, and also want to see education programs established to teach people in Africa to better manage their wildlife. "We don't want to spend our time catching criminals, we want to stop the crime from happening. That's the most effective enforcement you can do."