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Matters of Scale - Bioinvasions

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Weight of the total world catch of fish and seafood in a recent year
86 million tons
Weight of non-native jellyfish in the Black Sea that year
900 tons
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Percentage of the Great Lakes fish catch that was native salmon and trout in 1900
82
Percentage that was native salmon and trout in 1966, after overfishing, chemical pollution, and bioinvasions including the spread of the exotic predatory sea lamprey killed off the native fish
0.2
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Number of species of native birds in Hawaii in prehistoric times
111
Number of those species left today, after mass extinctions caused by human-carried invasions of exotic diseases and predatory pigs, rats, and other mammals
60
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Percentage of the crop harvest in medieval Europe that was destroyed by pests
30
Percentage of the crop harvest in the world today that is destroyed by pests
35 to 42
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Profit per hectare gained by Australian ranchers from the introduction of exotic forage plants
2
Cost per hectare to the Australian public of controlling those plants, which have no effective natural controls in that ecosystem
$30 to $120
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Sources: Chris Bright, senior editor of World Watch, from his forthcoming book Life Out of Bounds: Bioinvasion in a Borderless World (New York: W.W. Norton and Company), to be published this November.

Published in World Watch Magazine, July/August 1998, Volume 11, No. 4