How many marine fish species do bottom trawls catch? Researchers now have a list, and it’s long, running to some 3,000 species, according to a recent study. Bottom trawling is a commercially popular, and controversial, fishing method in which boats drag weighted nets along the seafloor. Usually they target commercially valuable marine life at the bottom of the ocean, such as rockfish, cod, and invertebrates like shrimp. However, the nets can, and do, catch all sorts of bottom-dwelling animals, such as seahorses. Study co-author Sarah Foster, who leads the Project Seahorse initiative at the University of British Columbia, Canada, said her team was trying to understand how bottom trawling affects seahorses when she was asked a simple question: How many fish species do bottom trawls catch, and what they are?   “I was surprised to realize there was no clear answer,” Foster told Mongabay by email. “One of the most basic questions in fisheries is what is actually being caught, and yet, for bottom trawling, that baseline understanding was missing.” So the researchers reviewed documents reporting bottom trawl catches, and recorded nearly 3,000 species of marine fish. “Our estimates suggest the true number could be double that,” Foster said. They also highlighted a size bias: larger fish tended to be documented more than smaller ones, which were often collectively listed under categories such as “mixed fish” or “trash fish.” “First, it means we don’t actually know what fisheries are catching — and we cannot manage what we do not measure,”…This article was originally published on Mongabay

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