Source: Scientific American
Author: Lucas Laursen
Fishing boats have dragged nets across the seafloor in pursuit of bottom-feeding fish and crustaceans since the Middle Ages. In recent decades, motorized fishing fleets, powered by government subsidies, have taken heavier nets deeper and farther offshore. The annual haul from international waters in 2010 was reported to be worth more than $600 million.
To see how bottom trawling is changing the ocean’s bottom, ecologist Antonio Pusceddu of the Marche Polytechnic University in Ancona, Italy, and his team took seafloor sediment samples at trawled and untouched sites off Spain’s northeastern coast between 500 and 2,000 meters below the surface. They then counted the number of individuals and species in those samples and measured the amount of carbon in the sediment.