A single, widespread fishing method hauls in nearly a quarter of all known marine fish species on Earth. Research led by the University of Glasgow in the United Kingdom has determined that bottom trawling catches approximately 3,000 different species, a staggering figure that includes hundreds already facing extinction.
## The Unseen Scale of a Global Industry
## A Bycatch Crisis for Threatened Wildlife
Scientists analyzed a global database of bottom trawl catches spanning three decades. The study, published in Nature, provides the first comprehensive estimate of the practice's total biodiversity impact. Bottom trawling involves dragging heavy nets across the seafloor to catch shrimp and fish like cod and sole. Its footprint is immense, affecting an estimated 14 million square kilometers of ocean.
The nets are indiscriminate. While targeting specific commercial species, they sweep up everything in their path. The research identified 1,082 species of sharks, rays, and chimaeras in the catch, a group particularly vulnerable to overfishing. Among them are 30 species listed as critically endangered, including the giant guitarfish and the green sawfish. Another 103 are classified as endangered or vulnerable.
Local fishing communities and conservationists care deeply because this scale of bycatch represents a direct threat to marine ecosystems and food security. The incidental capture of non-target and threatened species can deplete populations crucial for healthy oceans and, ultimately, the long-term viability of fisheries themselves. The sheer number of species affected highlights a systemic issue within one of the world's most common fishing techniques.
The significance of the findings lies in their unprecedented scope. By quantifying the global biodiversity toll of bottom trawling with hard numbers, the research moves the conversation beyond regional studies. It establishes a clear, data-driven baseline showing that industrial fishing's collateral damage is a planetary phenomenon, touching thousands of species across the world's continental shelves and slopes. This evidence creates a new imperative for fisheries management to account for entire ecosystems, not just stocks of a few popular fish.
