Protectionism, Trade, and Measures of Damage from Exotic Species Introductions

Unintentional introductions of nonindigenous plants, animals, and microbes cause significant ecological and agricultural crop damage worldwide. Trade in both manufactured and agricultural goods is a primary vector for such introductions. Fusing simple models of trade and biological introductions, we explore the links between trade, protectionism, and damage arising from exotic species introductions. We show that it is possible for freer trade to reduce damage arising from exotic species invasions. We also show how current measures of damage—heavily weighted toward agricultural damage—serve as misleading indicators of how restrictions to trade affect total losses arising from exotic species introductions.