Gaps and biases in knowledge about ecological impacts of bottom trawling

Given that bottom trawl fisheries are globally prevalent and exert significant ecological pressure, it is important to have a comprehensive understanding of their ecological impacts. Gaps and biases in available studies can mislead management and conservation efforts. We conducted a systematic global search of scientific and grey literature—including all taxa and study designs, in multiple languages—to document where research exist, what was assessed, and how. From 21 344 potential papers, we examined a random sample of 4000 and probed all 163 studies meeting our criteria. Research was overwhelmingly concentrated in temperate regions, with few studies carried out in areas with high bottom trawling intensity and biodiversity, such as Southeast Asia. Available studies covered a limited subset of taxa and impact types, and most of them relied on designs that did not control for both space and time. Our review of the availability of bottom trawl ecological research indicates that such fisheries proceed with substantial knowledge gaps across regions, taxa, and habitats, underscoring the need for caution in management and policy.