Evaluating the relationships between the legal and illegal international wildlife trades

Abstract

The international legal trade in wildlife can provide economic and other benefits, but when unsustainable can be a driver of population declines. This impact is enhanced by the additional burden of illegal trade. We combined law-enforcement time-series of seizures of wildlife goods imported into the United States (US) and the European Union (EU) with data on reported legal trade to evaluate the evidence for any relationships. Our analysis examined 28 (US) and 20 (EU) taxon-products with high volume and frequency of reported trade and seizures. On average, seizures added 28% and 9% to US and EU reported legal trade levels respectively, and in several cases exceeded legal imports. We detected a significant but weak overall positive relationship between seizure volumes and reported trade imported to the US over time, but none in the EU. Our findings suggest a complex and nuanced temporal association between the illegal and legal wildlife trades.