Ivory poachers tend to hunt elephants in just a few key spots in Africa, a new genetic analysis shows.
The DNA signatures of smuggled tusks seized by law enforcement officials over the last 20 years finger central and southeastern Africa as hotbeds of organized ivory trafficking crime and corruption, scientists suggest online June 18 in Science.
Other evidence had pointed to these areas before, but the new work “shows a smoking gun,” says conservation scientist Fiona Maisels of the Wildlife Conservation Society in New York City. Identifying major poaching spots may help officials zero in on big ivory cartels, she says, and that could curtail elephant killings across Africa.
Decades of illegal ivory trading have whittled the population of African elephants down to about 400,000. In recent years, poachers have killed roughly 50,000 elephants annually. To figure out where to focus protection efforts, scientists have tried to uncover where poaching is worst.
Tracking elephant populations and carcass locations has provided some clues. And shipment data from containers of seized ivory have helped sketch a rough picture of the contraband’s path out of the continent.
“So you have this idea of where a container moved and where it originated,” says conservation biologist George Wittemyer of Colorado State University in Fort Collins, “but you don’t know where the ivory itself came from.”
To find out, Samuel Wasser, a conservation geneticist at the University of Washington in Seattle, and colleagues genetically analyzed samples from 28 large ivory seizures made across Africa and Asia from 1996 to 2014. Then the team matched the DNA signature of each sample, a half dollar–sized disk carved from the base of a tusk, to a reference map charting the signatures of elephants from all over Africa.
With the map, the researchers could trace the origin of each piece of ivory. After 2006, the majority came from just two areas: in central Africa, a region that spans northeastern Gabon, northwestern Democratic Republic of Congo, the southeast tip of Cameroon, and the neighboring Dzanga Sangha Reserve in Central African Republic; and in southeastern Africa, a roughly 150,000-square-kilometer-swath of land from Tanzania to northern Mozambique.
Scientists had previously pegged Tanzania as a hub for poachers, Wasser says. “But we didn’t know how extreme it was,” he says. “It’s just mind blowing.”
A recent census of Africa’s elephants showed that Tanzania lost about 12,000 just last year. But the country hasn’t owned up to the problem, Wasser says. Tanzanian officials have suggested that maybe the elephants just left the country. But the new ivory data say otherwise: Researchers traced tons of ivory to populations of Tanzanian elephants. “This kind of evidence is hard to deny,” Wasser says.
The small number of poaching hot spots that Wasser’s team identified suggests that just a few large and powerful international crime cartels are responsible for most of the illegal ivory trade, Maisels says. Such a huge amount of trafficked ivory probably involves a vast network of corrupted officials. “You can’t move hundreds of tons of illegal material without the involvement of law enforcement agencies,” she says.
Interpol plans to use the ivory DNA evidence to determine where the organization should focus its efforts, Bill Clark of Interpol’s environmental crime unit said June 17 in a news briefing.