Search

Fisheries can adversely affect threatened bycatch species and vulnerable marine ecosystems (VMEs). Thresholds are unique amongst bycatch management methods in providing flexibility in individual participants' approaches to avoid exceeding limits, and particularly for individual vessel quotas, in incentivizing the innovation of effective and commercially viable solutions. This study assessed bycatch thresholds for sharks and relatives, air-breathing marine species and macroinvertebrate indicators for identifying benthic VMEs of 21 intergovernmental organizations and arrangements (IGOs). Seven IGOs lacking bycatch thresholds, who tended to have fewer members, might rely on bycatch management by national authorities. Sharks were the predominant focus. IGOs did not know if thresholds were reached for almost half of measures, likely due to compliance monitoring deficits. Individual vessel limits may be more equitable and prevent a race for fish. However, risk pools and fleetwide thresholds may be more effective when mitigation approaches for individual vessels are limited. No IGO uses individual transferable bycatch quotas or risk pools, which would be challenging to implement regionally. No thresholds were reference points of a harvest strategy. There were limited incidences of thresholds being reached. Thresholds might be set too high to meet objectives. When reached, there was high variability in management responses being systematically implemented. Addressing deficits of thresholds being set too low, inadequate compliance monitoring and inconsistent management response implementation could improve performance. Thresholds have the potential to be an effective component of regional bycatch management strategies, incentivizing fishers to minimize their individual and collective bycatch fishing mortality and adverse effects on VMEs. [ABSTRACT FROM AUTHOR]

Policy decisions should be guided by the relative degree of risk of error and bias and strength of evidence of the efficacy of alternative management interventions. This study describes the benefits and limitations of applying a sequential evidence hierarchy to evaluate alternative fisheries bycatch management strategies. Fisheries bycatch is an obstacle to global food and livelihood security and is a main anthropogenic threat to several threatened species. Independent synthesis of all accumulated information is a fundamental principle for developing transparent, evidence-informed regional conservation policy. Meta-analytic syntheses produce the most robust and generalizable findings that are optimal for guiding regional bycatch management. Otherwise, given too few studies to support robust meta-syntheses, decisions should rely on qualitative syntheses of accumulated studies. Bycatch mitigation methods with findings only available from studies with relatively weak forms of evidence, or lacking any evidence, should only be considered as a precautionary approach when more certain alternatives are unavailable. Strictly applying a hierarchical approach on study evidence to make policy decisions, however, risks ignoring potentially important findings derived from studies using methods low on an evidence hierarchy. Instead, in making bycatch management policies, authorities should account for all accumulated evidence and the implications of different approaches for testing different hypotheses. Fisheries bycatch policy guided, but not bounded, by a sequential evidence hierarchy promises to achieve ecological and socioeconomic objectives. [ABSTRACT FROM AUTHOR]