Published 23 Tháng mười 2013


ETIS: Dissecting the illegal ivory trade

Cambridge, UK, 23rd October 2013—The cutting-edge statistical model that lies behind each analysis of the Elephant Trade Information System (ETIS) has been made publicly available, through a paper published in the open access journal PLOS One.

Every reported ivory seizure makes a contribution to understanding the trade chain. © TRAFFIC

ETIS is the world’s largest database of elephant product seizures and contains the only extensive information on illicit trade available. Currently there are close to 20,000 records, representing law enforcement actions in around 100 countries and territories since 1989. 

ETIS is managed by TRAFFIC on behalf of Parties to CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora).

The paper’s authors, University of Reading, UK’s statisticians Fiona Underwood and Robert Burn and TRAFFIC’s Ivory Trade expert, Tom Milliken, outline the development of the modelling framework used to provide quantitative evidence on trends in the illegal ivory trade through analysis of ETIS records.

As the paper notes: “Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. 

“However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured.” 

To overcome such complexities, Underwood and Burn used “Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time.” 

“In simple language, the rigorous analysis allows adjustments for inherent biases and ‘sees through the raw data’ to produce a robust contemporary portrait of the illegal trade,” said Dr Fiona M. Underwood, an author of the PLOS ONE paper and a Visiting Senior Research Fellow at the University of Reading.

“Every reported ivory seizure makes a contribution to understanding the trade chain—whether it’s about the source, transit points or end destination.” 

“Our analysis helps fill in the blanks to find out who’s behind the trade, so that any country with a significant role—whether it’s making and reporting seizures itself or not—can be identified with certainty.” 

The PLOS One paper describes how activity in trade is represented by two indicators describing the number of illegal ivory transactions—Transactions Index—and the total weight of illegal ivory transactions—Weights Index—at global, regional or national levels.

Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. 

Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg, mainly moving from Central and East Africa to South-East and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants.

“Over more than 20 years, ETIS analysis has thrown light onto the dark world of ivory trafficking,” said Tom Milliken. 

“Raw ivory seizure figures alone tell an incomplete story: it is this kind of leading-edge science that takes that partial story and uncovers the truth behind what is actually happening on the ground.”

“The impact of Reading University’s statisticians on the conservation world has been immense: thanks to their robust analysis, countries most implicated in the global illegal ivory trade have been identified and pressure publicly put on them to take action.”