Study: $560 Billion Wasted by Bottom Trawling

Industrial fisheries that rely on bottom trawling to catch fish threw 437 million tons of fish and $560 billion overboard over the past 65 years, finds new research.

“Industrial fisheries do not bring everything they catch to port,” said Tim Cashion, lead author of the study and a researcher with the Sea Around Us initiative at the University of British Columbia’s Institute for the Oceans and Fisheries. “During the period we studied, they threw out over 750 million tons of fish and 60 percent of that waste was due to bottom trawlers alone.”

Bottom trawls are large nets that industrial fishing vessels drag along the seabed. They capture everything including deep-sea corals and sponge beds and non-target fish species which can be dumped back into the ocean.

Cashion and his colleagues identified the fishing tools used by industrial and artisanal fisheries in each maritime country and territory and paired them with the millions of records in the Sea Around Us catch database that include reported and unreported catches by fishing country, fishing sector, year and species. They found that, globally, industrial and artisanal fisheries caught 5.6 billion tons of fish in the last six and a half decades. While almost 28 percent of that catch was captured by industrial bottom trawl, this fishing technique accounts for nearly 60 percent of fisheries discards.

“They threw away fish that, even though are not the most valuable, are perfectly good for human consumption. Had they landed that catch, they would have made $560 billion according to our prices dataset. The worst part is that, in general, bottom trawlers are so expensive to operate that the only way to keep them afloat is by giving them government subsidies. In other words, it’s a wasteful and inefficient practice,” said Deng Palomares, co-author of the study and the Sea Around Us Project Manager.

Palomares added that, conversely, all small-scale fisheries combined were responsible for only 23 percent of the global catch or approximately 1.3 billion tons in the past 65 year, but their catch was worth significantly more because they use small gillnets, traps, lines, hand tools and similar utensils to catch specifically what they want. “Catching fewer quantities of higher-value species, such as crabs and lobsters, they made almost $200 billion.”

The study “Global use of marine fishing gears from 1950 to 2014: Catches and landed values by gear type and sector” was published in Fisheries Research.