A new study led by scientists at Woods Hole Oceanographic Institution (WHOI) finds that industrial-scale fishing has been removing substantial biomass from the ocean’s “twilight zone” for decades, challenging the common assumption that this vast midwater ecosystem remains largely unexploited. The research focuses on a poorly understood group of larger midwater fishes that the authors call the “dark web,” species, such as pomfrets and snake mackerels, that live in or move through the mesopelagic zone, roughly 200 to 1,000 meters below the surface. Unlike smaller fishes often sampled in research nets, larger species are frequently missed by traditional scientific surveys but are regularly caught in commercial fisheries…

The study identified evidence of heavy mesopelagic fishing pressure globally, including declining abundance, shrinking fish size, and pervasive under-reporting of fish catches that complicates fishery management.

Excerpt from Industrial fishing has been depleting midwater fish for decades, new WHOI study finds, Press Release, May 8, 2026