How elephant tusks, dung, and DNA research can help preserve the species

With a marquee touting performances of "The Lion King," a 25-ton rock crusher in New York's Time Square pulverized one ton of confiscated elephant ivory Friday morning.

The US Fish and Wildlife Service, which held the event, will use the residue in a public-education campaign about the elephant poaching crisis. But to Samuel Wasser, a conservation biologist at the University of Washington in Seattle, these events represent destroying evidence that could be used to save elephants.

Confiscated tusks represent a treasure trove of DNA, which he uses as biochemical trail markers leading to specific areas – to within 180 miles or less – where poachers killed the elephants bearing the tusks.

His goal is to pinpoint source regions for illicit ivory to focus law-enforcement efforts, as well as to cut through the "who, us?" posturing on the part of some source countries.

Some 434,000 African elephants remain on the continent, researchers say. Based on the 51 tons of ivory seized in 2013, that would translate to more than 50,000 elephants killed to extract their tusks, by some estimates. At that rate, elephants in Africa would virtually vanish by the early 2020s.

"It's a good thing to send this message, that we're saying that ivory is not worth it anymore," Dr. Wasser says. But once the conveyor belt starts to move, "they are destroying evidence" locked up in the DNA that can be extracted from the ivory.

The power of the DNA trail to pinpoint poaching is highlighted in a paper Wasser and colleagues published Thursday in Sciencexpress, the online adjunct to the journal Science.

During the past decade, the team has painstakingly mapped the distribution of elephant populations based on DNA extracted largely from dung. By comparing DNA extracted from captured ivory with the maps, the team identifies poaching hot spots.

The new study involved DNA extracted from samples taken from 28 large ivory seizures between 1996 and 2014. The team focused on seizures that involved 1,000 pounds or more, since quantities this large imply fairly sophisticated criminal groups behind the poaching.

Using ivory samples from these confiscations, the team found that since 2006, virtually all of the ivory came from two African "hot spots."

One hot spot involved forest elephants from a protected ecosystem known as the Tridom area, which encompasses nearly 57,000 square miles of rainforest in portions of Gabon, Cameroon, and the Republic of Congo. Between 2006 and 2014, this region accounted for 85 percent of the seized ivory removed from forest elephants.

The second and largest hot spot is eastern Africa, Wasser says. Here, between 2006 and 2014, two reserves were source regions for 85 percent of the seized ivory from savannah elephants: Tanzania's Selous Game Reserve was the primary source, with additional tusks coming from the Niassa Reserve in neighboring Mozambique.

Moreover, the DNA evidence also signals shifts in poaching hot spots. Since 2011, poaching in Tanzania has moved north, deeper into the country and toward Kenya, according to Wasser's research. 

Using DNA to identify ivory-poaching hot spots represents a powerful tool for combating illegal ivory trafficking, suggests George Amato, director of the Sackler Institute for Comparative Genomics at the American Museum of Natural History in New York.

DNA often has been used to test food or products to see if they come from endangered species.

In 2010, for instance, a team led by Scott Baker, associate director of the Marine Mammal Institute at Oregon State University in Newport, Ore., published the results of an analysis of sashimi samples taken from restaurants in Santa Monica, Calif., and in Seoul, South Korea. The team found that the samples contained meat from three species of whale protected under the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES).

This year, Dr. Baker and colleagues from the US and Japan reported using DNA to track the likely origin of products made from fin whales and sold in Japan between 1993 and 2009. The results suggested that Japanese whalers had been exploiting either an illegal, unreported, or undocumented source of fin whales in Antarctic waters, where commercial whaling for fin whales ended in the mid 1970s.

Dr. Amato, who has been building a library of DNA sequences from endangered species at the American Museum of Natural History, notes that, as with Baker's 2010 study, DNA has been used to test bush meat, fish, skins, and products made from them for illegal contents.

Short of an outright ban on trafficking in specific species, it may be legal to harvest species from one specific area but not from another, he adds.

"That's where you need the additional detail from from additional genetic markers that Sam has developed, " he says.

On one level, adding the information from DNA might seem like gilding the lily, Amato suggests.

"If we get information that Tanzania has lost more than half of its elephants in the last 10 years, and then we get information from Sam saying, 'Oh, by the way, most of that the ivory seized has come from Tanzania,' in some ways it's not a surprise. They had to go somewhere. Presumably they were harvested for ivory. It's not like they all just walked away," he says.

But Wasser's approach, in effect, provides the smoking gun. Taken together, monitoring population sizes and identifying hot spots from captured ivory provide "multiple lines of evidence indicating where significant illegal hunting is taking place," Amato says.

The DNA is important because it can be hard to trace the origins of tusks found in large cargo containers that may have passed through several ports between African and Asia, where ivory demand is heaviest.

Meanwhile, the confiscated ivory countries decide to crush can provide critical evidence.

"Out of all the crushes that have happened, only one country, the Philippines, gave us samples," Wasser says. "That was hugely important" for the analysis in his team's new paper.

The situation may be improving, he suggests.

In 2013, countries party to CITES passed a "decision" urging all countries seizing ivory shipments of 1,000 pounds or more to submit the ivory for origin analysis, Wasser says.

Since then, nearly 90 percent of all the seizures the 2013 decision covers are either in Wasser's lab, en route, or promised, he says.

Given the large amount of time it takes poachers – and the organized groups they work for – to build the infrastructure needed to handle such large quantities of ivory, getting samples in a timely fashion should make it easier to track hot spots as they shift.

"The most important thing is to get these two major hot spots contained and shut down," says Wasser of the locations his new study pinpoints. "That takes so much chaos out of the system and as new areas start to creep up, we can stay on top of them and nip them in the bud."