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Participatory decision tools enable stakeholders to reconcile conflicting natural resources management objectives. Fisheries targeting highly productive species can have profound impacts on co-occurring bycatch species with low fecundity and other life history traits that make them vulnerable to anthropogenic sources of mortality. This study developed a decision tool for integrated bycatch management for data-limited to data-rich fisheries, improving upon current piecemeal approaches. First, through a systematic literature review, participants compile a comprehensive database of methods to mitigate the catch and fishing mortality of threatened bycatch species. These mitigation methods are then categorized into tiers of a sequential mitigation hierarchy, where interventions that avoid capture are considered before those that minimize catchability, followed by methods that minimize fishing mortality, before approaches that offset residual impacts. The methods are also assembled within an evidence hierarchy, where findings from meta-analytic modelling studies are more robust and generalizable than from individual studies. The decision tool enables stakeholders to evaluate alternative bycatch management strategies’ efficacy at meeting specific and measurable objectives for mitigating the catch and mortality of bycatch and for costs from multispecies conflicts, economic viability, practicality and safety, while accounting for the fishery-specific feasibility of compliance monitoring of alternative bycatch management measures. Ongoing adaptation of the bycatch management framework addresses findings from performance assessments, updated evidence, new mitigation methods and changes to governance systems. The proposed decision tool therefore enables stakeholders to develop bycatch management frameworks that provide precautionary protection for the most vulnerable populations with acceptable tradeoffs.

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Current emission and mobilization rates of mercury (Hg) in the environment pose extensive threats to both wildlife and human health. Assessing the exposure risk and effects of Hg contamination in model species such as seabirds is essential to understand Hg risks at the population and ecosystem levels. The lesser black-backed gull (Larus fuscus), a generalist seabird species, is an excellent model species because it forages in both marine and terrestrial habitats, which in turn differ in their Hg exposure risk. To identify possible deleterious effects of Hg exposure on developing L. fuscus chicks, a dietary experiment was carried out and chicks were provided a marine, terrestrial, or mixed diet. The effects of embryonic and dietary Hg exposure on chick body condition and physiological state were assessed at different developmental stages until fledging age (30 d). Overall physiological condition was lower in chicks fed a predominantly marine diet, which coincided with higher Hg loads in blood and primary feathers. However, no effect of dietary uptake of Hg was observed on body condition or in terms of genotoxic damage. Body condition and genotoxic damage correlated instead with Hg exposure during embryonic development, which seems to indicate that embryonic exposure to Hg may result in carry-over effects on later chick development.

The impacts of fisheries on several charismatic marine fauna have been a subject of global concern. Sea snakes share the same habitats as many commercially important fish species and often end up as fisheries bycatch. Previous studies of bycatch from India have been limited to individual reports of mortality, with little information on the regional community structure of sea snakes. This study was carried out along the Konkan coast, off the central west coast of India, between 2016 and 2018, to determine trends in the bycatch of sea snakes in coastal fisheries. In this study, 922 sea snakes were encountered in 916.57 gillnet haul hours and 449.16 trawlers haul hours of fishing, comprising largely of two species: beaked sea snake (Hydrophis schistosus) and spine‐bellied sea snake (Hydrophis curtus) (83.05 and 16.94% respectively) which was in stark contrast to a similar study conducted in 2002–03, which recorded a dominance of H. curtus (84%) followed by H. schistosus (14%) in the same region. Both studies, however, indicated higher mortality in H. curtus than in H. schistosus in trawl nets. This study highlights the significant impact of non‐selective fishing practices on regional assemblages of other marine organisms such as sea snakes from South Asia, which has been relatively understudied, and the potential consequences for local ecosystems.

This a preprint and has not been peer reviewed. Data may be preliminary.

In the context of marine species declines in data‐limited regions, local ecological knowledge (LEK) is a valuable source of information on species ecology and historical trends. LEK can also help understand how threatened species exist within a local culture, in terms of their uses and values, and reveal attitudes towards their conservation. Rhino rays (guitarfish and wedgefish) are highly threatened by overfishing with most species critically endangered, yet poorly studied in countries like India that fish them the most. We drew on LEK to understand the socio‐ecological status of rhino rays in Goa, on the west coast of India. We investigated their habitat use and seasonality, interaction with fisheries, socio‐economic uses and relational values. We also explored attitudes of fishers towards rhino rays and their conservation. A combination of semistructured interviews and key informant interviews (88 in total) was conducted with fishers at multiple sites. Local knowledge suggests that nearshore habitats around river mouths form important nursery grounds for some rhino rays, and provided insights on their seasonality and breeding. Rhino rays appeared to be targeted historically but are entirely bycaught at present, with highest catches in gillnets and in the South Goa district, during September and October. LEK indicated that taxa like sawfish (Pristis spp.) and wedgefish (Rhynchobatus spp.) have severely declined or disappeared from this region. We coded different relational values, from recreation (rhino rays are consumed and enjoyed with alcohol) to symbolic values (rhino rays are considered lucky). All key informants expressed positive attitudes towards rhino ray conservation and stated that a ban on landing these species would have little to no impact on fisher earnings. The usefulness of LEK suggests it should be brought into the scientific mainstream to support development of more equitable and socially appropriate management plans. Fostering relational values can reinforce fishers' positive attitudes, thereby enhancing rhino ray conservation. Their low commercial value and potentially high post‐capture survival suggest that using norm‐based approaches to promote live release may be successful. Further research on rhino ray ecology and human dimensions can support the development of appropriate conservation interventions. Read the free Plain Language Summary for this article on the Journal blog.

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