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The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endangered, five are Endangered, and seven are Vulnerable. A further seven (10%) are Near Threatened, 33 (47.1%) are Least Concern, and 17 (24.2%) are Data Deficient. While the primary threat is overfishing, there are the first signs that climate change is contributing to elevated extinction risk through habitat reduction and inshore distributional shifts. By backcasting their status, few species were threatened in 1980, but this changed soon after the emergence of targeted shark and ray fisheries. South Africa has the highest national conservation responsibility, followed by Mozambique and Madagascar. Yet, while fisheries management and enforcement have improved in South Africa over recent decades, drastic improvements are urgently needed elsewhere. To avoid extinction and ensure robust populations of the region’s endemic sharks and rays and maintain ecosystem functionality, there is an urgent need for the strict protection of Critically Endangered and Endangered species and sustainable management of Vulnerable, Near Threatened, and Least Concern species, underpinned by species-level data collection and reduction of incidental catch.

The process of understanding the rapid global decline of sawfishes (Pristidae) has revealed great concern for their relatives, the wedgefishes (Rhinidae) and giant guitarfishes (Glaucostegidae), not least because all three families are targeted for their high-value and internationally-traded ‘white’ fins.The objective of this study was to assess the extinction risk of all 10 wedgefishes and 6 giant guitarfishes by applying the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, and to summarise their biogeography and habitat, life history, exploitation, use and trade, and population status.Wedgefishes and giant guitarfishes have overtaken sawfishes as the most imperilled marine fish families globally, with all but one of the 16 species facing an extremely high risk of extinction due to a combination of traits – limited biological productivity, presence in shallow waters overlapping with some of the most intense and increasing coastal fisheries in the world, and over-exploitation in target and bycatch fisheries driven by the need for animal protein and food security in coastal communities and trade in meat and high-value fins.Two species with very restricted ranges, the Clown Wedgefish (Rhynchobatus cooki) of the Indo-Malay Archipelago and the False Shark Ray (Rhynchorhina mauritaniensis) of Mauritania may be very close to extinction.Only the Eyebrow Wedgefish (Rhynchobatus palpebratus) is not assessed as Critically Endangered, due to it occurring primarily in Australia where fishing pressure is low, and some management measures are in place. Australia represents a ‘lifeboat’ for the three wedgefish and one giant guitarfish species occurring there.To conserve populations and permit recovery, a suite of measures will be required which will need to include species protection, spatial management, bycatch mitigation, and harvest and international trade management, all of which will be dependent on effective enforcement.

The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endangered, five are Endangered, and seven are Vulnerable. A further seven (10%) are Near Threatened, 33 (47.1%) are Least Concern, and 17 (24.2%) are Data Deficient. While the primary threat is overfishing, there are the first signs that climate change is contributing to elevated extinction risk through habitat reduction and inshore distributional shifts. By backcasting their status, few species were threatened in 1980, but this changed soon after the emergence of targeted shark and ray fisheries. South Africa has the highest national conservation responsibility, followed by Mozambique and Madagascar. Yet, while fisheries management and enforcement have improved in South Africa over recent decades, drastic improvements are urgently needed elsewhere. To avoid extinction and ensure robust populations and future food security, there is an urgent need for the strict protection of Critically Endangered and Endangered species and sustainable management of all species, underpinned by species-level data collection and bycatch reduction.

Summary The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes—sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species were threatened. Now, 391 (32.6%) species are threatened with extinction. When this percentage of threat is applied to Data Deficient species, more than one-third (37.5%) of chondrichthyans are estimated to be threatened, with much of this change resulting from new information. Three species are Critically Endangered (Possibly Extinct), representing possibly the first global marine fish extinctions due to overfishing. Consequently, the chondrichthyan extinction rate is potentially 25 extinctions per million species years, comparable to that of terrestrial vertebrates. Overfishing is the universal threat affecting all 391 threatened species and is the sole threat for 67.3% of species and interacts with three other threats for the remaining third: loss and degradation of habitat (31.2% of threatened species), climate change (10.2%), and pollution (6.9%). Species are disproportionately threatened in tropical and subtropical coastal waters. Science-based limits on fishing, effective marine protected areas, and approaches that reduce or eliminate fishing mortality are urgently needed to minimize mortality of threatened species and ensure sustainable catch and trade of others. Immediate action is essential to prevent further extinctions and protect the potential for food security and ecosystem functions provided by this iconic lineage of predators.

SummarySharks and rays are possibly the most threatened Class of marine fishes and their declines can be halted if protected areas are optimised to benefit these species. We identify spatial priorities for all 63 endemic sharks and rays in the marine biodiversity hotspot, the Western Indian Ocean (WIO). Collectively, while the WIO nations currently surpass the 10% Aichi ocean protection target, this amounts to a dismal protection of only 1.57% of each species’ distribution range. We show that the entire ranges of all endemics can be achieved by protecting 11% of EEZs of WIO nations, well within reach of the new 30% of oceans by 2030 target. Regional management bodies exist, which if taken advantage of to implement shark and ray management, provide opportunities to implement more efficient management across the region. We recommend key management actions to implement and explicit incentivisation of international cooperation in the post-2020 biodiversity framework.Science for SocietyThe past decade has seen massive growth in the establishment of marine protected areas (MPAs), driven by the Aichi biodiversity target of protecting 10% of all ocean areas. This expansion of MPAs, however, has largely occurred in areas residual to extractive uses, often coinciding with less threatened areas of lower conservation value. This coming decade will see a further push to ensure 30% of the oceans are protected by 2030. It is important to understand how existing and future MPAs should be placed to benefit threatened biodiversity. Currently this is unclear for sharks and rays, comprising a species group that is the most evolutionarily distinct vertebrate radiation in the world and also one of the most threatened. We identify both regional and national conservation priorities for expanding marine protected areas to benefit all 63 endemic sharks and rays occurring in the Western Indian Ocean region. We find that the region has already exceeded the 10% ocean protection target, but this amounts to an average of only 1.57% protection of the distribution ranges of these species. We show that protecting the top 10% priority sites will conserve almost half of the geographic range of each species yet require only 1.16% of the total EEZ – a tiny fraction of the 30% by 2030 target. We also show that regional collaboration among all nations can result in more spatially efficient conservation priorities. We recommend that the post-2020 biodiversity framework needs to explicitly incentivise regional cooperation between nations to efficiently achieve urgent targets and maximise benefits to biodiversity.

Many important areas identified for conservation priorities focus on areas of high species richness, however, it is unclear whether these areas change depending on what aspect of richness is considered (e.g. evolutionary distinctiveness, endemicity, or threatened species). Furthermore, little is known of the extent of spatial congruency between biodiversity measures in the marine realm. Here, we used the distribution maps of all known marine sharks, rays, and chimaeras (class Chondrichthyes) to examine the extent of spatial congruency across the hotspots of three measures of species richness: total number of species, evolutionarily distinct species, and endemic species. We assessed the spatial congruency between hotspots considering all species, as well as on the subset of the threatened species only. We consider three definitions of hotspot (2.5%, 5%, and 10% of cells with the highest numbers of species) and three levels of spatial resolution (1°, 4°, and 8° grid cells). Overall, we found low congruency among all three measures of species richness, with the threatened species comprising a smaller subset of the overall species patterns irrespective of hotspot definition. Areas of congruency at 1° and 5% richest cells contain over half (64%) of all sharks and rays and occurred off the coasts of: (1) Northern Mexico Gulf of California, (2) USA Gulf of Mexico, (3) Ecuador, (4) Uruguay and southern Brazil, (5) South Africa, southern Mozambique, and southern Namibia, (6) Japan, Taiwan, and parts of southern China, and (7) eastern and western Australia. Coarsening resolution increases congruency two-fold for all species but remains relatively low for threatened measures, and geographic locations of congruent areas also change. Finally, for pairwise comparisons of biodiversity measures, evolutionarily distinct species richness had the highest overlap with total species richness regardless of resolution or definition of hotspot. We suggest that focusing conservation attention solely on areas of high total species richness will not necessarily contribute efforts towards species that are most at risk, nor will it protect other important dimensions of species richness.

Aim Regional-scale assessments are frequently conceived to guide the strategic application of conservation actions. Although changes to priority areas from initial assessments are inevitable, the transition from regional-scale assessment to implementing local actions is poorly understood. An outstanding question concerns the frequency with which regionally assessed priorities should be updated as actions are implemented. We address this gap by simulating the incremental implementation of local actions guided by regional conservation assessments, exploring how update frequency can influence aspects of translating regional assessments to local actions. Location Fiji coral reefs. Methods Our simulations were designed within the framework of systematic conservation planning, with implemented actions simulated based on conservation value in achieving objectives and feature rarity. Other decision rule-sets were put in place to simulate on-the-ground negotiations that are often necessary when transitioning from regional-scale conservation assessments to local actions. We use our simulations to evaluate how the frequency of updating regional priorities influences (1) total time taken to achieve objectives represented by numbers of planning units investigated, (2) total extent of final reserve systems and (3) spatial overlap between initial regional priorities and final implemented reserves. Results Changes in the frequencies of updating did not influence the time taken to achieve conservation objectives, nor the total extent of final reserve systems. However, there was a significant difference in the number of times planning units were re-investigated for implementing actions within in scenarios that involved more frequent updates. Spatial overlap between initial regional priorities and final implemented reserves increased with decreases in update frequency. Main conclusions We find two potential benefits to updating priorities more frequently: (1) faster achievement of objectives for high-priority features and (2) greater potential to capitalize on areas previously investigated. Our findings provide insights into trade-offs to consider regarding the frequency of updating regional assessments, which varies depending on the planning context.

Each year, hundreds of conservation plans are developed to direct limited resources toward conservation in priority areas. Conservation plans are developed at different levels, defined here as points on a range of spatial extent varying from global to local. However, approaches to integrate plans effectively across levels remain elusive. To plan across multiple levels most effectively, the relative strengths and weaknesses of planning at different levels must be understood. Taking the Coral Triangle region of the western Pacific Ocean as a case study, we apply an adapted social-ecological system (SES) framework to assess the scalar coverage of conservation plans, i.e., the extent to which plans developed at one level adequately consider the social and ecological levels and components (i.e., resource units, resource systems, governance systems, actors) of an SES. No conservation plans we assessed had complete cross-level coverage. Plans most adequately addressed social and ecological components at the same level of planning and, to a lesser extent, lower levels. In line with previous literature suggesting that social factors are most relevant at local levels, we found that local-level plans engaged with the greatest number of stakeholder groups, whereas higher level plans more adequately addressed ecological components. Given that it appears more practicable for higher level plans to consider components at lower levels, the onus should fall on higher level planning to link to lower levels. Achieving complete cross-level coverage will require vertical interactions between planning processes at different levels, and conceiving of planning processes across all levels as connected planning systems. We demonstrate how an adapted SES framework can be used by conservation planners to assess the cross-level coverage of their own plans and to formulate appropriate conservation objectives to address social and ecological components at different levels.

Problems of scale abound in the governance of complex social-ecological systems. Conservation governance, for example, typically occurs at a single scale, but needs to inform governance and action at other scales to be truly effective at achieving social and ecological outcomes. This process is conventionally conceived as unidirectional – either scaling down or scaling up – in the way it both exploits and creates the natural, social, human, institutional, and financial resources and benefits that are collectively known as conservation ‘capital’. Here we analyse multiscale conservation governance and the different types of capital that impede or facilitate its effectiveness. Comparative analysis of conservation planning in Papua New Guinea and the Solomon Islands, through in-depth document review, key informant interview, and participant observation, reveals limited evidence of unidirectional processes. Instead, we observe multidirectional scaling pathways, cultivated by the following six scale-explicit characteristics of effective conservation governance: 1) multiscale understanding, 2) scale jumping, 3) scaled leadership characteristics, 4) scaled stakeholder engagement, 5) scaled policy frameworks, and 6) scaled institutional settings. While the latter four are familiar concepts, though not always recognised as explicitly scalar, we know little about the first two attributes of conservation governance. Based on this novelty and relevance, we propose a new form of capital – ‘scalar capital’ – to complement natural, social, human, institutional, and financial capitals as both input and outcome of effective conservation governance. We find that scalar capital facilitates flows of different resources (data, conservation objectives, practitioner experience, institutional support, and funding) in multiple directions. Critically, we present empirical evidence that conservation governance can foster scalar capital to improve outcomes across multiple scales.