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Marine megafauna exposed to fisheries bycatch belong to some of the most threatened taxonomic groups and include apex and mesopredators that contribute to ecosystem regulation. Fisheries bycatch is a major threat to the conservation of albatrosses, large petrels and other pelagic seabirds. Using data sourced from a fisheries electronic monitoring system, we assessed the effects of the time-of-day and relative depth of fishing on seabird and target species catch rates for a Pacific Ocean pelagic longline fishery that targets albacore tuna with an apparently high albatross bycatch rate. Using a Bayesian inference workflow with a spatially-explicit generalized additive mixed model for albacore tuna and generalized linear mixed regression models both for combined albatrosses and combined seabirds, we found that time-of-day and fishing depth did not significantly affect the target species catch rate while night-time deep setting had > 99% lower albatross and total seabird catch rates compared to both deep and shallow partial day-time sets. This provides the first evidence that night-time setting in combination with fishing deep reduces seabird catch risk and may be commercially viable in this and similar albacore tuna longline fisheries. Findings support evidence-informed interventions to reduce the mortality of threatened seabird bycatch species in pelagic longline fisheries. [ABSTRACT FROM AUTHOR]

Robust assessments of the effects of fishing require accounting for components of fishing mortality, including post‐release fishing mortality (Fr). Random‐effects meta‐analysis synthesized Fr in seven pelagic shark species captured, tagged and released with 401 pop‐up satellite archival tags compiled from 33 studies and three gears (longline, purse‐seine, rod & reel). The majority of Fr outcomes occurred within days of release, and the summary effect size for Fr was 0.27 [95% CI: 0.19–0.36], ranging from a low pooled effect size of 0.17 for blue shark (Prionace glauca, Carcharhinidae) to 0.38 (silky shark, Carcharhinus falciformis, Carcharhinidae). Fr rates in blue shark were consistent over dissimilar spatial and temporal scales, and results from earlier meta‐analysis were replicated, which is the most powerful way to authenticate results. Condition at tagging was a strong predictor, and dichotomized survival outcomes in silky shark and no sex‐, size‐, location‐ or gear‐specific Fr rates were demonstrated. Meta‐analyses and sensitivity analyses indicated exposure to risk factors and conditions whilst caught on the gear probably had the largest explanatory effect on Fr, rather than stressors incurred during handling and release. Records from 549 tagged istiophorid billfishes (six species, three gears, 43 studies) demonstrated they are more robust to stressors sustained during capture, handling and release than pelagic sharks. Findings from previous meta‐analysis on Fr rates in white marlin (Kajikia albida, Istiophoridae) were replicated. Synthesized Fr rates enable prioritizing approaches to mitigate by‐catch fishing mortality, to improve the quality of stock and ecological risk assessments and to expand our knowledge of factors influencing trophic structure. [ABSTRACT FROM AUTHOR]

A performance assessment was conducted of regional fisheries management organizations' ( RFMOs') bycatch governance, one element of an ecosystem approach to fisheries management. Obtaining a mean score of 25%, with a 64% CV, collectively the RFMOs have large governance deficits. Individually, there has been mixed progress, with some RFMOs having made substantial progress for some governance elements. There has been nominal progress in gradually transitioning to ecosystem-based fisheries management: controls largely do not account for broad or multispecies effects of fishing, and cross-sectoral marine spatial planning is limited. Regional observers collect half of minimum information needed to assess the efficacy of bycatch measures. Over two-thirds of RFMO-managed fisheries lack regional observer coverage. International exchange of observers occurs in one-third of programmes. There is no open access to research-grade regional observer data. Ecological risk assessments focus on effects of bycatch removals on vulnerable species groups and effects of fishing on vulnerable benthic marine ecosystems. RFMOs largely do not assess or manage cryptic, generally undetectable sources of fishing mortality. Binding measures address about one-third of bycatch problems. Eighty per cent of measures lack explicit performance standards against which to assess efficacy. Measures are piecemeal, developed without considering potential conflicts across vulnerable groups. RFMOs employ 60% of surveillance methods required to assess compliance. A lack of transparency and limited reporting of inspection effort, identified infractions, enforcement actions and outcomes further limits the ability to assess compliance. Augmented harmonization could help to fill identified deficits. [ABSTRACT FROM AUTHOR]

Industrial fishing, instrumental in feeding the world's population while providing a livelihood to many people, also presents a variety of hazards to the health of the ocean, including the accumulation of derelict fishing gear. Although direct evidence of harm from derelict gear is abundant, efforts to quantify and assess the threats posed by it are confounded in part by the tremendous diversity of fishing gear and techniques. In this paper, we advance a novel analytic framework for describing the use of fishing gear that can be applied to evaluate the environmental impacts that arise from fishing activity. We model fishing as a unit process comprising three successive characterizations, each of which can be observed and validated independently: the intensity of fishing effort, the material intensity of gear, and the intensity of the environmental effect. We present the method as an open‐source computation system with a library of gear models that can be reviewed and extended by the research community. We apply the program to estimate the generation of derelict gear for several different gear types and discuss how it can be expanded to advance the understanding of the impacts of industrial fishing at the global scale. This article met the requirements for a Gold–Gold JIE data openness badge described at http://jie.click/badges. [ABSTRACT FROM AUTHOR]

The article examines three seabird bycatch avoidance method used in pelagic longline fisheries based in Hawaii. Two of the treatments made use of branch lines that were placed through 9 meters and 6.5 meters long underwater setting chutes while the third entailed a setting from the side of the vessel. Side-setting has been found to be the most effective of the methods wherein a crew throwing baited hooks was placed about 8 meters forward from the port-stern corner. According to the author, side-setting can be used to reduce seabird mortality when combined with adequate line weighting.

Derelict fishing gear is a highly visible source of marine plastic pollution, causing mortality and ecosystem degradation with uncertain long‐term consequences. The quantity of derelict gear entering the oceans remains unknown because of heterogeneity in fishing gear and effort, as well as inadequate monitoring. Prior studies have been limited in scope to specific fisheries and regions, and large‐scale estimates lack an empirical basis. It is critically important for decision makers to have credible information in order to design effective remediation efforts. We estimated the amount of industrial fishing effort and the associated plastic debris entering the ocean globally each year from lost fishing gear. Using remote observations of fishing vessel activity paired with technical fishing gear models, we generated a bounding estimate for gear operation and loss worldwide in 2018. We estimate that industrial trawl, purse‐seine and pelagic longline fisheries operated 2.1 Mt of plastic gear over 2018 to obtain 49.7 Mt of retained and discarded catch, representing 74% of industrial marine capture globally. The median estimate for plastic gear lost during the use of these gear types was 48.4 kt (95% confidence interval: 28.4–99.5 kt). This estimate excludes abandoned and discarded gear. Improved observation, especially of small‐scale fisheries, is needed to better understand the sources of derelict gear. These findings serve as a benchmark for future monitoring and management efforts to reduce derelict gear in the global ocean. [ABSTRACT FROM AUTHOR]