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Comprehensive bycatch assessment in US fisheries for prioritizing management


Wild-capture fisheries help provide food security to billions of people, yet bycatch of non-target species threatens ecosystem health and fishery sustainability. Appropriate monitoring and fisheries management can mitigate bycatch but require standardized bycatch data to be robustly recorded and effectively disseminated. Here we integrated and analysed 30,473 species-specific bycatch records from 95 US fisheries in 2010–2015. We examined patterns in fish and invertebrate, marine mammal, seabird and sea turtle bycatch and developed a standardized scoring system, the relative bycatch index, to assess bycatch performance of each fishery. The estimated amount of fish and invertebrate discards totalled 1.93 million tonnes (4.26 billion pounds) over the 6-year period. We found that the national discard rate is 10.5%, considerably lower than past estimates. Results from our relative bycatch index analysis can be used to facilitate management intervention strategies for particular fisheries or gear types, such as shrimp and otter trawls and several pelagic longline and gillnet fisheries, which had the poorest bycatch performance. These findings underscore the need for continued, high-quality, easily accessible bycatch information to better support fisheries management in the United States and globally.

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Fig. 1: Proportion of US federally managed fisheries appearing in the NBR sorted by gear type in five NMFS reporting regions.
Fig. 2: Bycatch patterns in all fisheries.
Fig. 3: Distribution of relative bycatch index (RBI) scores.
Fig. 4: The annual relative bycatch index (RBI) score for 61 fisheries that have 6 years of data (2010–2015).

Data availability

All the raw NBR data can be explored, queried, visualized and downloaded at:

Code availability

All code used to analyse data and generate plots found in the paper is at:


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We thank the fisheries observers who collected bycatch data that informed this work. Further, we thank the team at the National Observer Program (NOAA/NMFS) for drafting the NBRs, which provided the raw data used in this study. In addition, we appreciate data management assistance by C. Donegan and an internal review by S. Mesnick and J. Carretta (NOAA Southwest Fisheries Science Center). This work was made possible by a California Sea Grant Fellowship to M.S.S. and funding through the Fisheries Information Systems NOAA/NMFS.

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M.S.S., L.R.B., S.J.B. and E.L.H. conceived and designed the study. M.S.S., S.B., H.W. and A.H. analysed the data. H.W. created the web application with input from all authors. M.S.S. wrote the manuscript with input and edits from all authors.

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Correspondence to Matthew S. Savoca.

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Savoca, M.S., Brodie, S., Welch, H. et al. Comprehensive bycatch assessment in US fisheries for prioritizing management. Nat Sustain 3, 472–480 (2020).

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