Comprehensive Analysis of Statistical Precision in U.S. Bycatch Estimates: Persistent Uncertainty and Future Priorities

The Magnuson-Stevens Act requires standardized bycatch reporting methodologies to accurately estimate bycatch, but few fisheries in the U.S. have implemented them to date. This lack of progress has perpetuated poor data quality, which undermines fisheries management goals, hinders rebuilding timelines, and could even compromise fishing opportunities. We conducted an analysis of the overall statistical precision within the National Marine Fisheries Service National Bycatch Report by compiling the number of stock bycatch estimates accompanied by a coefficient of variation (CV) and the number of those values that meet national guidelines for precision goals. The recently published draft update of the National Bycatch Report estimates bycatch for 80 fisheries across six regions. Our results show that only one-third of stock bycatch estimates are accompanied by a CV and less than one-quarter of those CVs meet the 30% precision goal established almost a decade ago. Overall, only four U.S. fisheries have average CVs less than 30%, with regional averages of 50% and 140% in the Northeast and Southeast, respectively. Here we present these and other statistical patterns across fisheries, regions, and gear types. While significant progress has been made since 2005 data were first comprehensively assessed, this high level of uncertainty fails to meet established national precision standards and signifies that existing bycatch estimates are often insufficient for informing in-season management measures. This comprehensive analysis identifies priority fisheries and stocks in need of continued improvement and shows the importance of alternative approaches to account for this uncertainty, such as increasing the mathematical buffer used when calculating annual catch limits. It is imperative that robust standardized bycatch reporting methodologies are established across all U.S. fisheries in the near future, as is required by law. Combined with innovative and effective monitoring, standardized bycatch reporting will be the best way to ensure total fishing mortality is accounted for across regions and gear types, thereby making progress toward rebuilding depleted stocks and managing for resilient and abundant fishery resources in the future.