Scientists have used a revolutionary genetic technique to pinpoint the area of Africa where smugglers are slaughtering elephants to feed the worldwide illegal ivory trade.

Using a DNA map of Africa’s elephants, they have found that most recent seizures of tusks can be traced to animals that had grazed in the Selous and Niassa game reserves on the Tanzania and Mozambique borders.

The discovery suggests that only a handful of cartels are responsible for most of the world’s booming trade in illegal ivory and for the annual slaughter of tens of thousands of elephants. The extent of this trade is revealed through recent seizures of thousands of tusks in separate raids on docks in Taiwan, Hong Kong, Vietnam, the Philippines and Japan. These were aimed at satisfying the far east’s growing appetite for ivory, a new status symbol for the middle classes of the region’s swelling industrialised economies.

As a result, ivory prices have soared from $200 a kilogram in 2004 to more than $6,000. At the same time, scientists estimate that between 8% and 10% of Africa’s elephants are now being slaughtered each year to meet demand.

“In the past, law enforcement agencies – including Interpol – thought these shipments of ivory had been put together by traders cherry-picking small stockpiles across Africa,” said Professor Sam Wasser, director of the University of Washington’s Centre for Conservation Biology, where the DNA elephant map was developed.

“Our work shows that isn’t true. The vast majority of poaching is being carried out by a few big organisations – possibly one or two major syndicates – that are targeting one area and then hammering its elephants. It is grim, but it also suggests we can target our anti-poaching efforts very specifically by focussing efforts on these regions.”

At present, Tanzania is at the centre of the world’s ivory slaughter. However, other work by Wasser and his team indicates that different areas, including parts of Zambia and Malawi, have been targeted in the recent past.

Ivory poaching was halted by an international campaign in the 1990s after it reached a peak between 1979 and 1989, when more than 700,000 elephants were killed for their tusks. However, aid that helps African nations fight poachers has dried up and the illegal ivory trade has returned to its previous high levels.

Killing for tusks is a particularly gruesome trade. Elephants are highly intelligent animals whose sophisticated social ties are exploited by poachers. They will often shoot young elephants to draw in a grieving parent, which is then killed for its tusks. “Our estimates suggest that more than 38,000 elephants were killed using techniques such as this in 2006 and that the annual death rate is even higher today,” said Wasser.

His team’s technique – outlined in the current issue of Scientific American – involves two separate sets of analyses. First, volunteers and researchers across Africa collected samples of elephant dung. Each contains plentiful amounts of DNA from cells, sloughed from the intestines of individual animals. These provide material for DNA fingerprints, which have since been mapped for the whole of Africa. Animals from one area have very similar DNA fingerprints, the researchers have found.

As part of the second analysis, a section of tusk seized from smugglers is ground up and its DNA is carefully extracted. Again a DNA fingerprint is made and compared with those on the dung map, in order to pinpoint the origin of the elephant.

In this way, Wasser and his colleagues analysed ivory seized when more than 11 tonnes of tusks were found in containers in raids on Taiwan and Hong Kong docks in July and August 2006. About 1,500 tusks were discovered and all were traced to elephants from the Selous game reserve, a Unesco heritage site in Tanzania, and the nearby Niassa game reserve in Mozambique. However, Japanese authorities – who had made another seizure of ivory that summer in Osaka – refused to co-operate and have since burnt the 260 tusks they found before their origins could be established. “You can draw your own conclusions,” said Wasser.

Since then, major seizures of ivory have been made in Vietnam and the Philippines, both this year, and Wasser and his team are now preparing to use their DNA map to trace its origins.

“Ivory is now traded globally in the same illegal manner as drugs and weapons,” said Wasser. “It is shameful that this has happened and we need to press the countries whose elephants are being targeted this way and get them to halt this trade.”