The direct impacts of fishing on chondrichthyans (sharks, rays and chimeras) are well established. Here we review a largely unreported, often misinterpreted and poorly understood indirect impact of fishing on these animals — capture-induced parturition (either premature birth or abortion). Although direct mortality of discarded sharks and rays has been estimated, the prevalence of abortion/premature birth and subsequent generational mortality remains largely unstudied. We synthesize a diffuse body of literature to reveal that a conservative estimate of > 12% of live bearing elasmobranchs (n = 88 species) show capture-induced parturition. For those species with adequate data, we estimate capture-induced parturition events ranging from 2 to 85% of pregnant females (average 24%). To date, capture-induced parturition has only been observed in live-bearing species. We compile data on threat-levels, method of capture, reproductive mode and gestation extent of premature/aborted embryos. We also utilise social media to identify 41 social-media links depicting a capture-induced parturition event which provide supplementary visual evidence for the phenomenon. The mortality of embryos will have implications for elasmobranch populations, and there are limited options to deal with this problem. This review is the first to synthesize available data on capture-induced parturition in sharks and rays, and highlights an important ethical and management issue for fishers and managers deserving of much greater attention.

The direct impacts of fishing on chondrichthyans (sharks, rays and chimeras) are well established.Here we review a largely unreported, often misinterpreted and poorly understood indirect impact of fishing on these animalscapture-induced parturition (either premature birth or abortion). Although direct mortality of discarded sharks and rays has been estimated, the prevalence of abortion/premature birth and subsequent generational mortality remains largely unstudied. We synthesize a diffuse body of literature to reveal that a conservative estimate of > 12% of live bearing elasmobranchs (n = 88 species) show capture-induced parturition. For those species with adequate data, we estimate capture-induced parturition events ranging from 2 to 85% of pregnant females (average 24%). To date, capture-induced parturition has only been observed in livebearing species. We compile data on threat-levels, method of capture, reproductive mode and gestation extent of premature/aborted embryos. We also utilise social media to identify 41 socialmedia links depicting a capture-induced parturition event which provide supplementary visual evidence for the phenomenon. The mortality of embryos will have implications for elasmobranch populations, and there are limited options to deal with this problem. This review is the first to synthesize available data on capture-induced parturition in sharks and rays, and highlights an important ethical and management issue for fishers and managers deserving of much greater attention.Table 1 List of terms and definitions as referred to in this review. List of definitions Stress-induced parturitionThe premature birthing of offspring stimulated by physiological processes which involve a response to a 'stressor' via complex pathways modulated by hormones. Captureinduced parturitionThe birthing of offspring prompted by interaction with fishing gear. The pathways stimulating birth are expected to vary and could be caused by interactions between physical trauma and physiological stress. Premature birthThe parturition of pre-term offspring, which often have reduced fitness due to lack of development and smaller body size. AbortionThe termination of a pregnancy by the expulsion of a foetus or embryo before it can survive outside the uterus. SharkShark generally refers to those elasmobranchs with gill slits located laterally and includes all the nine orders of chondrichthyans that are not deemed skates, rays or chimeras: sawsharks (Pristiophoriformes), angel sharks (Squatiniformes), dogfish (Squaliformes), sixgilled sharks (Hexanchiformes), mackerel sharks (Lamniformes), ground sharks (Carcharhiniformes), carpetsharks (Orectolobiformes), bullhead sharks (Heterodontiformes) and bramble sharks (Echinorhiniformes). RayRay generally refers to the three orders of chondrichthyans that are not deemed sharks, skates or chimeras. All rays are live-bearing and have gill slits that are located ventrally: stingrays (Myliobatiformes), electric rays (Torpediniformes) and shovelnose rays/guitarfish (Rhinopristiformes). SkateS...

‘Shark attack’ presents a considerable social‐environmental challenge. Each year a small number of people are injured or killed by shark bite. Concurrently, sharks and other marine life are subject to unprecedented anthropogenic pressures. Shark hazard management varies globally, but lethal strategies are common, with negative consequences for species and environments. Of particular concern are the effects for threatened species. Lethal strategies have recently come under criticism, based on the negative effects for marine life, effectiveness for human safety and inconsistency with contemporary values. Moves to improve both safety and conservation can be hindered by polarized debate. We present a case study of the world's longest‐running lethal shark hazard management program, the Shark Meshing (Bather Protection) Program, New South Wales, Australia. We take an interdisciplinary approach to bring into conversation factors that contribute to safety and conservation outcomes. To date, most research focuses on one or other of these areas. We seek to synthesize the factors that are not previously considered in relation to each other. Our aims were to: (a) identify and critique the diverse factors that determine the outcomes of the program; (b) assess the negative effects of the program for sharks and other marine life; and (c) assess the effectiveness of the program for reducing threat of shark interactions. We find that: (a) multiple social and environmental factors contribute to program outcomes; (b) total shark numbers and populations of key target species – white shark (Carcharodon carcharias), tiger shark (Galeocerdo cuvier) and bull shark (Carcharhinus leucas) – have declined over the program's 80 years, as have a number of non‐target species; (c) incidence of shark bite has declined since the program's introduction, but two external points warrant attention. First, key factors influencing the shark bite incidence are frequently overlooked, namely changing cultures of beach‐ and ocean‐use, advances in beach patrol, and emergency and medical response. Second, the proportion of bites leading to fatality has decreased significantly in recent decades. Beach patrol and emergency response contribute to human safety and well‐being without the negative consequences of lethal strategies. As such, they offer a focus for future shark hazard management and research. A free Plain Language Summary can be found within the Supporting Information of this article.

Delineation of population structure (i.e. stocks) is crucial to successfully manage exploited species and to address conservation concerns for threatened species. Fish migration and associated movements are key mechanisms through which discrete populations mix and are thus important determinants of population structure. Detailed information on fish migration and movements is becoming more accessible through advances in telemetry and analysis methods however such information is not yet used systematically in stock structure assessment. Here, we described how detections of acoustically tagged fish across a continental‐scale array of underwater acoustic receivers were used to assess stock structure and connectivity in seven teleost and seven shark species and compared to findings from genetic and conventional tagging. Network analysis revealed previously unknown population connections in some species, and in others bolstered support for existing stock discrimination by identifying nodes and routes important for connectivity. Species with less variability in their movements required smaller sample sizes (45–50 individuals) to reveal useful stock structure information. Our study shows the power of continental‐scale acoustic telemetry networks to detect movements among fishery jurisdictions. We highlight methodological issues that need to be considered in the design of acoustic telemetry studies for investigating stock structure and the interpretation of the resulting data. The advent of broad‐scale acoustic telemetry networks across the globe provides new avenues to understand how movement informs population structure and can lead to improved management.