Intra-gear variation in sea turtle bycatch: Implications for fisheries management

Cambiè, Giulia; Jribi, Imed; Cambera, Irene; Vagnoli, Giulia; Freggi, Daniela; Casale, Paolo

doi:10.1016/j.fishres.2019.105405

Cited by 9 publications

(5 citation statements)

References 34 publications

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“…This and previous studies show that spatial information of bycatch can only be provided by fishers through voluntary logbook programmes (e.g. Cuevas et al, 2018; Cambie et al, 2020; Casale et al, 2020), especially where such data are not required by law, and therefore their involvement should be considered essential for the success of conservation projects. VMS data are being used to study the relationship between fishing effort and bycatch (e.g.…”

Section: Discussionmentioning

confidence: 57%

Voluntary fishing logbooks are essential for unveiling unsustainable bycatch levels and appropriate mitigating measures: The case of sea turtles in the Gulf of Manfredonia, Adriatic Sea

Baldi

Salvemini²,

Attanasio³

et al. 2022

Aquatic Conservation

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1. Studying the impact of bycatch on marine megafauna, including sea turtles, is challenging for a variety of technical and biological reasons. The Mediterranean Sea has among the highest levels of turtle bycatch globally, notably of the loggerhead sea turtle (Caretta caretta), and bottom trawling represents a particularly relevant threat.2. Bottom trawlers from a recently discovered neritic foraging area, the Gulf of Manfredonia, reported 1,152 loggerhead turtles incidentally caught in the period 2015-2020. Capture locations were available for 497 turtles. These data were complemented by the distribution of fishing effort obtained by the vessel monitoring system.3. High bycatch rates were observed, leading to more than an estimated 5,600 annual captures and to the death of a minimum of 560 large individuals with high reproductive value. These findings are extremely concerning for the affected population and require immediate action. A strong seasonality of turtle bycatch was observed, with most captures occurring in November-March when fishing effort occurs in shallow waters where turtles concentrate all year round. 4. Therefore, a seasonal approach (e.g. adopting measures only in the high-turtle bycatch season) can be pursued as long as the spatial distribution of fishing effort varies among seasons. However, such a spatio-temporal pattern should be monitored; then, in the case of change, although more difficult to implement, an area-based conservation approach should be pursued. Several recommendations are provided, including the urgent implementation of turtle excluder devices, at least on a seasonal basis.

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Section: Discussionmentioning

confidence: 57%

Voluntary fishing logbooks are essential for unveiling unsustainable bycatch levels and appropriate mitigating measures: The case of sea turtles in the Gulf of Manfredonia, Adriatic Sea

Baldi

Salvemini²,

Attanasio³

et al. 2022

Aquatic Conservation

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“…A key parameter is the total bycatch per metier (group of fishing operations targeting a specific assemblage of species, using specific gear, during a precise period of the year and/or within a specific area; Deporte et al, 2012) per year, which includes a measure of fishing effort (Equation 1). Although less precise than a metier-based approach (Cambiè et al, 2020), by-catch rates per fishing gear per year can be used when data on metier are not available.…”

Section: Indicator Measurement and Data Requirementsmentioning

confidence: 99%

Toward a common approach for assessing the conservation status of marine turtle species within the european marine strategy framework directive

Girard

Monsinjon³

et al. 2022

Front. Mar. Sci.

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Environmental policies, including the European Marine Strategy Framework Directive (MSFD), generally rely on the measurement of indicators to assess the good environmental status (GES) and ensure the protection of marine ecosystems. However, depending on available scientific knowledge and monitoring programs in place, quantitative GES assessments are not always feasible. This is specifically the case for marine turtle species, which are listed under the Biodiversity Descriptor of the MSFD. Relying on an expert consultation, the goal of this study was to develop indicators and a common assessment approach to be employed by European Union Member States to evaluate the status of marine turtle populations in the frame of the MSFD. A dedicated international expert group was created to explore and test potential assessment approaches, in coherence with other environmental policies (i.e. Habitats Directive, OSPAR and Barcelona Conventions). Following a series of workshops, the group provided recommendations for the GES assessment of marine turtles. In particular, indicators and assessment methods were defined, setting a solid basis for future MSFD assessments. Although knowledge gaps remain, data requirements identified in this study will guide future data collection initiatives and inform monitoring programs implemented by EU Member States. Overall this study highlights the value of international collaboration for the conservation of vulnerable species, such as marine turtles.

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“…It facilitates a more objective selection of the most appropriate number of clusters compared to simple visual inspection (Rousseeuw, 1987). One popular technique for selecting the most appropriate number of métiers is to maximize the average silhouette width across all métiers (e.g., Castro et al, 2010Castro et al, , 2011Cambiè et al, 2020). However, due to the high dimensionality and inherent disorder of our fisheries dataset and the fact that the optimal solution may still exhibit strong biases toward one or the other metrics, we were cautious to not solely select the k value that resulted in the maximum average silhouette width across all métiers.…”

Section: Choosing K and Cluster Validationmentioning

confidence: 99%

A Robust Métier-Based Approach to Classifying Fishing Practices Within Commercial Fisheries

et al. 2020

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Intra-gear variation in sea turtle bycatch: Implications for fisheries management

Cited by 9 publications

References 34 publications

Voluntary fishing logbooks are essential for unveiling unsustainable bycatch levels and appropriate mitigating measures: The case of sea turtles in the Gulf of Manfredonia, Adriatic Sea

Voluntary fishing logbooks are essential for unveiling unsustainable bycatch levels and appropriate mitigating measures: The case of sea turtles in the Gulf of Manfredonia, Adriatic Sea

Toward a common approach for assessing the conservation status of marine turtle species within the european marine strategy framework directive

A Robust Métier-Based Approach to Classifying Fishing Practices Within Commercial Fisheries

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