Tight Lines: Bottom Trawling has smaller global footprint than estimated

NARRAGANSETT, Rhode Island — Previous accounts of the harmful footprint of bottom trawling, a common practice in the commercial fishing world, might have been greatly exaggerated, according to a recently published report.

Bottom trawling only touches 14 percent of seafloor, a smaller global footprint than previously estimated, a group of oceanographers were able to determine from gathered data. Seafood harvested from bottom trawling, according to the report, accounts for 25 percent of the world’s edible marine life stock.

“A new analysis of the ocean regions around the world shows that bottom trawling … occurs on just 14 percent of the seafloor along continental shelves and slopes,” a University of Rhode Island (URI) statement on the published report said. “These findings indicate that the footprint often had been overestimated significantly.”

High-resolution data from 24 ocean regions around the world were analyzed by dozens of scientists representing 22 countries. Findings were published in the Proceedings of the National Academy of Sciences on Oct. 8. Data was collected from satellite monitoring of 4.8 million square miles of seafloor shallower than 3,280 feet.

The University of Washington’s Ricardo Amoroso and International Council for the Exploration of the Sea’s Simon Jennings were lead authors on the report. Amoroso was at the University of Washington as a postdoctoral researcher in the School of Aquatic and Fishery Sciences.

Commercial fisheries commonly engage in bottom trawling to catch large amounts of certain bottom-dwelling species, such as cod, rockfish, shrimp and sole. A net or dredge is used to catch bottom-dwellers from the seafloor along continental shelves and slopes to scoop.

“The technique impacts ecosystems because other marine life and habitats can be killed or disturbed unintentionally as nets sweep the seafloor,” URI’s statement on the published report said.

The practice of bottom trawling has regularly been criticized as negatively affecting marine life, but scientists and researchers lacked any clarity on the true effect of bottom trawling.

“Until now, scientists had been unable to determine with precision how much of the seafloor, called the footprint, is trawled worldwide,” URI’s official statement on the published report said.

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