Ecological merits of trawling the oceans

摘要

Trawling the seabed for fish is an environmental disaster; it wrecks ecosystems, destroys fish stocks and leaves behind a marine desert. Right? Environment campaigners say so. But there is growing evidence that the effect is sometimes very different, with trawling increasing fish stocks from the North Sea to the California coast. A new modelling study may for the first time have demonstrated why. Trawlers attach large nets to a metal beam dragged across the seabed to catch bottom-dwelling fish. Greenpeace likens it to "driving a huge bulldozer through a forest", leaving a flat, featureless desert on the seabed. Trawling clearly does remove fish, large crustaceans and shellfish, says Daniel van Denderen of the Wageningen Institute for Marine Resources and Ecosystem Studies in the Netherlands. But this is a lucky break for softer, smaller species lurking in the sandy seabed, such as worms. They survive and, with fewer rivals, flourish.