Fish & Ships: Using overlap between Atlantic fishing fleets and highly migratory pelagic species to reveal hotspots of potential management interest

Due to their large ecological niche and high commercial value, highly migratory species are exposed to fishing pressure across the Atlantic Ocean. Although international management collects spatial catch and effort data, accuracy and representativeness are difficult to verify. Fleet behavior can increasingly be monitored using ship tracking technologies. Simultaneously, electronic tagging provides location estimates as well as broader insights into seasonal habitat suitability. Here, we combined electronic tagging datasets from 778 satellite and archival tags with environmental data to model distributions for Atlantic bluefin tuna, blue sharks, swordfish, and blue marlin. We overlaid these maps with longline effort estimates derived from AIS data to identify times and regions of high overlap between species and fleet. Comparing with species-specific CPUEs reported to management, we identified regions where, for specific species and seasons, reported catches were low compared to species density predicted from presence data and habitat models. This data science approach may be useful to management enforcement agencies and compliance committees, potentially identifying regions where fleets may be under-reporting or other management assumptions may be invalid.