Bottom trawls, enormous fishing nets that are dragged across the sea floor, clear-cut everything living in their path. The mouths of the largest nets are big enough to swallow a Boeing 747 Jumbo Jet, and trawls and dredges can destroy century-old reefs in mere moments.

How Extensive is the Damage? (Fig. A)

• The largest deep-sea bottom trawling ships—“supertrawlers” —are 450 feet or longer (the length of 1.5 football fields).

• A large trawler can drag over a half-acre swath of seabed with one pass.

• High-seas bottom trawlers destroy 580 square miles of seabed each day.

• Each year, the world’s fleet of bottom trawlers disturbs a seabed area twice the size of the contiguous United States.

• Deep-sea trawling destroys seabed habitat at a faster rate than the aggregate loss of the world’s tropical rain forests.

• European scientists have calculated that bottom-dragging trawlers in the North Sea destroy 16 pounds of marine animals for every pound of marketable sole that is caught.

Trawler Doors (Fig. B)

Heavy doors keep the mouth of the net open and on the seafloor. Rubber and steel rockhoppers roll across the seafloor, while floats lift open the net above them.