Burning ivory sends a strong message, but it also destroys criminal evidence (Image: CARL DE SOUZA/AFP/Getty Images)

Destroying stockpiles of ivory sends a powerful anti-poaching message but it also obliterates vital forensic evidence contained within the DNA in the ivory.

“Unfortunately, it destroys evidence,” says Sam Wasser of the University of Washington in Seattle, whose team used ivory stockpiles to identify two major poaching hotspots in Africa.

They first set up a reference map of all major elephant populations in Africa, based on 15,000 samples of DNA collected from elephant dung across the continent.


They then traced back illegal ivory from 28 major seizures to their geographical origin by analysing its DNA.

Their analysis reveals that since 2006, almost all the seized ivory has come from just two places: Tanzania – which lost 60 per cent of its elephants over the past five years – and the Tridom region, a stretch of western Africa spanning parts of Gabon, the Republic of Congo and Cameroon.

Two poaching hotspots

“We were very surprised to find that over the past decade, the ivory came from just two locations in Africa,” Wasser said at a press conference announcing the results. “It means we can target these areas for law enforcement.”

The information has already been useful in focusing efforts to catch poachers and smugglers, and to unravel trafficking networks, says William Clark of Interpol, one of the authors of the study.

“It’s helped us a great deal, because so many false trails are left deliberately by the smugglers,” he says. “Now we have this DNA repository, it helps us establish investigating priorities.”

Ivory stockpiles are often destroyed – one of the most recent saw 6.15 tonnes destroyed in China.

While this destruction is necessary – otherwise the ivory leaks out onto the black market due to corruption – it also wipes out the evidence.

The solution, says Wasser, is to save small samples, allowing him to add its DNA and any known history to his collection. “It should be required that they take a sub-sample so the data’s not lost,” he says.

Sample every tusk

Clark agrees. “Every tusk should be sampled,” he says. “We’ve seen the stockpiles get pilfered. So it’s best to take samples, then destroy.”

“Forensic examination of all seized ivory is an excellent idea,” says Richard Thomas, spokesman for the UK wildlife monitoring network TRAFFIC.

He adds that the most recent meeting of the Convention on Trade in Endangered Species (CITES) agreed to oblige countries to do routine examination and sub-sampling within 90 days of all new large-scale seizures.

“It costs some planning and effort to sub-sample prior to destruction, but doesn’t affect the impact or message of burning the seized goods,” says Rus Hoelzel of Durham University, UK. “Beyond helping to determine the geographic location of poaching, DNA forensics helps to identify the broader network associated with the illegal trade, critical for enforcement.”

Wasser says that 50,000 elephants are now being poached each year, and only 470,000 individuals remain. And while tackling demand is important, the strategy is too slow on its own to save elephant populations.

“We need other tactics, and the most important thing is to get these poaching hotspots in Africa contained and shut down,” he says.

Journal reference: Science, DOI:10.1126/science.aaa2457