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 magnified by the additional burden of illegal trade, yet how it covaries with legal trade remains little explored. 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 products derived from CITES‐listed species with high volume and frequency of both 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 into the US over time, but not into the EU. These results highlight the importance of maintaining long‐term records of border seizures and enforcement effort, and accounting for illegal trade where possible in non‐detriment findings. Our findings suggest a complex and nuanced temporal association between the illegal and legal wildlife trades.

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评估合法和非法的国际野生动植物贸易之间的关系

野生动植物的国际合法贸易可以带来经济和其他利益，但是如果不可持续，可能会导致人口减少。非法贸易的额外负担将这种影响放大了，但是，它与合法贸易的关系如何变迁仍然鲜有探索。我们将执法时间序列中从美国（US）和欧盟（EU）进口的野生动植物产品的缉获量与报告的合法贸易数据结合起来，以评估任何关系的证据。我们的分析检查了来自CITES所列物种的28种美国和20种欧盟产品，这些产品的贸易量和缉获量都很高，而且频率很高。平均而言，缉获量分别使美国和欧盟报告的合法贸易水平增加了28％和9％，并且在某些情况下超过了合法进口量。我们发现缉获量与报告的一段时间内进入美国而不是进入欧盟的贸易之间存在显着但弱的总体正相关关系。这些结果突出了保持边境扣押和执法工作长期记录的重要性，并在可能的情况下在无损调查结果中考虑非法贸易。我们的发现表明，非法和合法野生动植物交易之间存在着复杂而细微的时间关联。