Benefits And Costs Of Migrating Species

January 19, 2001

Whether by choice or chance, when humans have gone to new places, other species new to those lands have often journeyed with them. While some migrations can impose heavy social costs -- such as the introduction of new diseases -- the benefits are often enormous.

  • The potato traveled from the Andes to Europe, North America and elsewhere, as did the tomato; soybeans probably reached the Americas from China; exotic plants and animals have made their way around the world thanks to collectors; and when Europeans migrated overseas, they took along wheat, barley, rye, cattle, pigs, horses, sheep and goats.
  • Today, introductions of isolated species to new habitats are occurring with stunning rapidity -- as global imports of agricultural products and industrial raw materials have shot from $55 billion in value in 1965 to $480 billion in 1990, according to the World Resources Institute.
  • Yet only a tiny proportion of alien species establish new populations and of those only about one in 10 becomes a pest.
  • One in five of the United States' 4,500 exotic species has caused serious economic or ecological harm -- and of the U.S.' threatened native species, 40 percent can blame their decline on the newcomers, experts report.

The costs are hard to quantify. One government estimate puts the cost of a selection of 79 harmful species in the U.S. at a cumulative total of $96 billion since 1900.

If enough people believe that the arrival of alien species means economic harm, more will be spent to prevent it -- and that is already happening. But some scientists believe beneficial species are getting the heave-ho along with their more malevolent brethren.

Source: "New Flora and Fauna for Old," Economist, December 23, 2000.

 

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