A third assessment of global marine fisheries discards
This third update of FAO’s global discard estimate adopted the ‘fishery-by-fishery’ approach employed in the second discards assessment published in 2005. The update included publicly available discard data in the last 20 years to establish a baseline of a time series of global marine fisheries discards. This is essential for monitoring the status and trends of discard management, which is the first step of the ecosystem approach to fisheries management cycle. In addition, the study developed a new fisheries data table incorporating landings data from the FAO Global Capture Production dataset (FishStat J) from 2010 to 2014, which allocated the landings to over 2 000 fisheries worldwide.
The current study estimated that the annual discards from global marine capture fisheries between 2010 and 2014 was 9.1 million tonnes (95% CI: 6.7 – 16.1 million tonnes). About 46 percent (4.2 million tonnes) of total annual discards were from bottom trawls that included otter trawls, shrimp trawls, pair bottom trawls, twin otter trawls and beam trawls.
The study included a synthesis of estimates of bycatch and discards of endangered, threatened and protected (ETP) species. Substantial advances have been made in quantifying fisheries interactions with such species so as to make informed decisions on their protection. However, many challenges remain, especially for small-scale fisheries. The development of standardized data collection techniques, risk-based sampling and sharing of data across agencies and regions will help to identify management priorities and allow implementation and enforcement of mitigation measures.
A review of previous research showed that discard practices were often related to a wide range of factors, so it is difficult to assess the effectiveness of fishery management actions on the amount and practice of discards. Many regulations are inconsistently enforced, and their implementation is often less strict than intended. Piecemeal approaches in many bycatch and discards management measures can result in unintended cross-taxa conflicts, where regulations designed to reduce bycatch and/or discards of one species or species group may increase bycatch and/or discards of another. Examination of approaches to accounting for and mitigating against pre-catch, post-capture and ghost fishing mortalities demonstrates that an understanding of the relative importance of factors affecting indirect fishing mortality is necessary for estimating total fishing-induced mortality and for designing and implementing mitigation measures.
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