Species’ traits and exposure as a future lens for quantifying seabird bycatch vulnerability in global fisheries

Abstract

Fisheries bycatch, the incidental mortality of non-target species, is a global threat to seabirds and a major driver of their declines worldwide. Identifying the most vulnerable species is core to developing sustainable fisheries management strategies that aim to improve conservation outcomes. To advance this goal, we present a preliminary vulnerability framework for the context of bycatch mortality that integrates dimensions of species' exposure (the extent a species' range overlaps with fishing activities and the magnitude of activities experienced), sensitivity (a species' likelihood of bycatch mortality when it interacts with fisheries), and adaptive capacity (the ability for populations to adapt and recover from bycatch mortalities). This allows us to classify species into five vulnerability classes. The framework combines species' traits and distribution ranges for 341 seabirds, along with a spatially resolved fishing effort dataset. Overall, we find most species have high-vulnerability scores for the sensitivity and adaptive capacity dimensions. By contrast, exposure is more variable across species, and thus the median scores calculated within seabird families is low. We further find 46 species have high exposure to fishing activities, but are not identified as vulnerable to bycatch, whilst 133 species have lower exposure, but are vulnerable to bycatch. The framework has been valuable for revealing patterns between and within the vulnerability dimensions. Further methodological development, additional traits, and greater availability of threat data are required to advance the framework and provide a new lens for quantifying seabird bycatch vulnerability that complements existing efforts, such as the International Union for Conservation of Nature (IUCN) Red List. Les traits et l'exposition des espèces comme perspective d'avenir pour la quantification de la vulnérabilité des oiseaux marins capturés accidentellement dans les pêcheries mondialesRÉSUMÉ. Les prises accidentelles dans les pêcheries, c'est-à-dire la mortalité accidentelle d'espèces non ciblées, constituent une menace globale pour les oiseaux de mer et un facteur important de leur déclin dans le monde entier. L'identification des espèces les plus vulnérables est essentielle au développement de stratégies de gestion durable des pêches visant à améliorer les résultats en matière de conservation. Pour atteindre cet objectif, nous présentons un cadre préliminaire de vulnérabilité dans le contexte de la mortalité due aux prises accidentelles, qui intègre les dimensions de l'exposition des espèces (la mesure dans laquelle l'aire de répartition d'une espèce chevauche les activités de pêche et l'ampleur des activités subies), de la sensibilité (la probabilité pour une espèce de subir une prise accidentelle lorsqu'elle interagit avec les pêcheries) et de la capacité d'adaptation (la capacité des populations à s'adapter et à se rétablir des mortalités dues aux prises accidentelles). Cela nous permet de classer les espèces en cinq classes de vulnérabilité. Le...

Trophic guilds of marine predators in the California Current Large Marine Ecosystem

“…Quantitative information concerning trophic relationships of marine species is fundamental to the construction and performance of ecosystem models, development of effective ecosystem-based fisheries management (EBFM) strategies, and support of emerging trait-based approaches to ecological risk assessment (Ainsworth et al, 2010;Foden et al, 2013;Livingston et al, 2017;Richards et al, 2022). Ecosystem models can augment singlespecies models by enabling the evaluation of a broad range of interactions and dynamics that single species models are less capable of addressing, particularly with respect to competition, predation (e.g., natural mortality), and the role of environmental variability.…”

“…Especially in regions where predator-prey dynamics are poorly understood, creative efforts are needed to estimate trophic relationships better as a basis for EBFM. Likewise, trait-based approaches can improve the power of ecological risk assessments to identify species or populations most likely to suffer adverse consequences from other anthropogenic disturbances (e.g., fishing gear interactions, climate change), supporting more effective conservation planning (Foden et al, 2013;Richards et al, 2022).…”

“…By considering predator taxa collectively within guilds that use similar resources, management strategies or decisions (such as the level of fishing mortality allowed on forage species) can be more readily evaluated in terms of ecosystem effects (Gaichas et al, 2011;Smith et al, 2011;Pikitch et al, 2014). Information on predator guilds can similarly be used to support more effective assessment and prioritization for management of other foraging-related impacts on threatened, endangered, and protected living marine resources (Richards et al, 2022). Further, quantifying the spatial extent of guilds provides context for evaluating the geographic footprint of environmental influences and management actions on guild members.…”