October 10, 2018 — About a quarter of the world’s seafood caught in the ocean comes from bottom trawling, a method that involves towing a net along the seabed on continental shelves and slopes to catch shrimp, cod, rockfish, sole and other kinds of bottom-dwelling fish and shellfish. The technique impacts these seafloor ecosystems because other marine life and habitats can be unintentionally killed or disturbed as nets pass across the seafloor.
Scientists agree that extensive bottom trawling can negatively affect marine ecosystems, but the central question — how much of the total area, or footprint, is trawled worldwide — has been hard to nail down.
A new analysis that uses high-resolution data for 24 ocean regions in Africa, Europe, North and South America, and Australasia shows that only 14 percent of the overall seafloor shallower than 1,000 meters (3,280 feet) is trawled. Most trawl fishing happens in this depth range along continental shelves and slopes in the world’s oceans. The study focused on this depth range, covering an area of about 7.8 million square kilometers of ocean.
The paper, appearing in the Proceedings of the National Academy of Sciences, brought together 57 scientists based in 22 countries, with expertise in mapping fishing activity from satellite monitoring and fishing logbook data. It shows that the footprint of bottom-trawl fishing on continental shelves and slopes across the world’s oceans often has been substantially overestimated.
Read the full story at Eco Magazine