Tuesday May 12, 2026
ECO —
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.
“Much of the discussion around the ocean twilight zone has assumed large-scale fishing there has not really begun,” said Martin Arostegui, lead author of the study and research associate at WHOI. “Our study shows that for these larger midwater fishes, that is simply not the case.”
Through an analysis of decades of catch records from the Hawai‘i-based longline fishery and other published examples from around the world, researchers found that catches of these midwater species have grown substantially and, in some fisheries, now exceed catches of traditional target species such as tuna and swordfish