Studying sharks in the Anthropocene: an overview of research efforts targeting human-related threats over elasmobranchs

Abstract Over the past centuries, humans have been transforming the biogeophysical landscape that carried species evolution over the geological past. Sharks and their relatives represent one of the lineages struggling to keep pace with the new challenges of the Anthropocene, with over a third of their species under extinction risk. Increasingly aware of the ecological and socioeconomic value of this group, researchers have been striving to evaluate the scale of anthropogenic threats and how to mitigate their impact. Conscious of the difficulties implicit to such endeavour, we implement a hierarchical systematic mapping approach to methodically explore the scientific landscape aiming to assess the effects of anthropogenic threats over sharks and their relatives. Starting from a pool of 502 studies featuring both shark and human dimensions, records were categorized according to the direction of the concerns expressed and the focus of the research, then further categorizing the 175 studies explicitly striving to understand the impacts of anthropogenic threats(i.e., fisheries, pollution, habitat degradation, human intrusion, and climate change) according to their methodological profile, along with the underlying biological scope and spatial scale. The results highlight how the shift from “sharks as a threat” to “sharks under threat” is denoted in the scientific discourse and can be observed over time. Further, although fisheries have long been recognized as the most pressing threats to this group, a recent relative increase in the assessment threats such as pollution and climate change can be observed, respectively suggesting an increased awareness of shark conservation concerns and a growing focus on emergent and forward-looking challenges. Still, methodological profiles highlight persisting research gaps and potential geographical and taxonomic bias that should be further addressed as we move to improve our understanding of how sharks may fare in the oceans of tomorrow and strive to support evidence-based conservation and management policies.