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More than 5000 species of wildlife are being bought and sold legally and illegally around the world, according to new estimates. That figure may be far higher than previously thought.

Previous assessments of this trade have looked at data from either the International Union for Conservation of Nature Red List or the Convention on International Trade in Endangered Species of Wild Fauna and Flora. For the new estimate, David Edwards at the University of Sheffield, UK, and his colleagues combined information from both sources and overlaid it with maps of where the species are found.

They found 5579 species of vertebrates – nearly a fifth of the total vertebrates examined – are traded. This is 40 to 60 per cent higher than previous estimates. But certain groups are targeted more than others. It turns out that 27 per cent of known mammal species are traded, for example.


South America, South-East Asia and central and south-east Africa emerged as the epicentres of the industry.

The exercise revealed that people tend to trade species with larger body sizes and some form of evolutionary distinctiveness. That insight was in turn used to build a model for predicting which species may be traded in the future. This suggested that between 303 and 3152 more species are at risk.

Edwards says the team’s aim wasn’t just to provide a list of threatened species but “to allow a kind of proactive switch, to start thinking about species that are already potentially at risk of being drawn into trade – a kind of watch list”. Such information should help target resources for monitoring legal trade and stopping illegal trade, he says.

Richard Thomas at wildlife trade monitoring group TRAFFIC says the study has some drawbacks. “It has a premise that being in trade is fundamentally bad, and equates to a species being threatened. However, there’s plenty of examples of species that have benefited as a result of being in trade,” he says. He also points out that the research only covers numbers of species being traded, not the volumes of each species.

Journal reference: Science, DOI: 10.1126/science.aav5327