Broadband measurements of the acoustic target strength of mesopelagic fishes

The mesopelagic zone (∼200–1000 m) is defined by depths where small amounts of sunlight still penetrate but light levels are insufficient to support photosynthetic activity. This region is one of Earth’s largest ecosystems and is home to a diverse community of marine animals. Biomass estimates for mesopelagic regions, based on acoustic measurements, suggest small fishes at these depths may dominate total fish biomass. These estimates, however,...