Marine ecosystems are increasingly threatened by overfishing, pollution, coastal development and climate change, underscoring the need for long-term, representative information on key fish populations and habitats to inform management and policy. Underwater fish observation (UFObs) techniques, such as Underwater Visual Census (UVC), stereo-Baited Remote Underwater Video (stereo-BRUV) and Remotely Operated Vehicles (ROVs), play a key role in sustaining long-term data collection. Despite technological advancements, gaps persist in understanding research focus, geographic distribution and methodological biases inherent in these methods. We conducted a scientometric analysis of 1443 peer-reviewed publications (1953-2023), employing natural language processing and network analysis to map the research landscape. We identified 15 knowledge clusters, including marine protected areas, apex predator conservation and reef ecosystems. Our findings reveal increasing use of BRUVS and ROVs in studies of marine protected areas and subsea infrastructure, while UVC remains prevalent in shallow coral reef research. Geographic representation is skewed, with the field dominated by researchers based in Australia and the United States, and underrepresented in Africa and Southeast Asia. This imbalance highlights the need for more inclusive, globally coordinated monitoring and reporting. Our results underscore the urgency of standardising protocols within each observation method and developing interoperable reporting frameworks across techniques to maximise data comparability and foster international collaboration. Addressing these challenges will strengthen the field's capacity to inform global conservation strategies and support sustainable fisheries management.

Most of the global population has inadequate micronutrient intake1, leading to cascading adverse effects on economies and human health2. Aquatic invertebrates are a diverse, productive and socioecologically important food3,4, yet their contribution to human nutrition is frequently overlooked5. Here, combining aquaculture production, capture fisheries and nutrient composition data, we quantify the contribution of aquatic invertebrates to global nutrient supplies. Furthermore, as nutrient information for invertebrates is sparse, using species-specific trait data, we develop a predictive model to estimate the nutrient content of over 50,000 invertebrate species registered in SeaLifeBase, a global database focused on marine non-fish species. We show aquatic invertebrates are exceptionally nutrient dense, with current aquatic invertebrate production supplying the equivalent annual requirement for over 5 billion people in terms of vitamin B12 and selenium; over 1 billion people for copper, omega 3 fatty acids, iodine and zinc; and over 100 million people for nutrients such as vitamins B2 and B3, iron, manganese and magnesium. Nutrient composition differs among taxonomic groups, consumption patterns (for example, body parts and processing form), and environmental and life-history factors such as the habitat or thermal regime the species lives in. Overall, provided that ecological sustainability is attained and socioeconomic and food-system barriers (such as food safety, access, affordability, cultural acceptance and bioavailability) do not prevent invertebrate consumption and nutrient uptake, our study highlights the potential benefits of integrating aquatic invertebrates into dietary portfolios across global societies, mainstreaming their nutritional importance in development projects, sustainability assessments and food policy.

Abstract Seafood nutrients from global fisheries are of increasing importance for research and policy in food security and nutrition. As the chemical composition of fish is determined by what they eat, their energetic demands, and the environment in which they live, nutrient content reflects aspects of physiology and life history, ecological and environmental traits, as well as evolutionary history. Here we present data from Bayesian model estimates of 12 key nutrients (calcium, iron, phosphorus, magnesium, selenium, zinc, vitamin A, vitamin B9, vitamin B12, vitamin D, omega-3 fatty acids, and protein) in wild fish, using a database of reported nutrient content for freshwater and marine species. We then predict the nutrient content of 5588 fish species with traits available from FishBase. We compare our previous model using traits alone with a new model of both traits and phylogeny, and present the data, code, and predictions for models coded in PyMC. These models and predictions, made freely available through FishBase, can be used to explore the historical, current, and future nutrient content of fisheries catch.

Rays of the family Rhinopteridae Jordan Evermann, 1896 are highly migratory and widely distributed in warm tropical and temperate waters. Along the Brazilian coast, the presence of two species has been recorded: Rhinoptera bonasus Mitchill, 1815 and Rhinoptera brasiliensis Müller, 1836. These stingrays are commonly caught as bycatch in trawl fisheries, however, the two species lack distinctive external morphological features that allow for reliable differentiation—species identification is primarily based on the shape and arrangement of teeth in the buccal plates. This study aimed to investigate the evolutionary history of the genus Rhinoptera and to explore which evolutionary drivers, such as biogeographic events or behavioral traits, have influenced its diversification. To achieve this, we analyzed both mitochondrial and nuclear genetic markers, focusing on the species occurring along the Brazilian coast. Specimens of both species were collected across various locations in Brazil, and additional sequences from other Rhinoptera species were obtained from GenBank. Our results reveal the presence of multiple cryptic species within Rhinoptera, particularly within R. bonasus, and likely in Rhinoptera steindachneri Evermann Jenkins, 1891 and Rhinoptera javanica Müller Henle, 1841. Notably, R. bonasus does not occur in Brazilian waters nor in parts of the Caribbean where a distinct cryptic sister lineage was identified. Based on our findings, we propose the resurrection of Rhinoptera lalandii Müller Henle, 1841 as the species representing the lineage found along the Brazilian coast and the Eastern Atlantic Ocean. We suggest that philopatric behavior may represent one of several factors potentially influencing diversification within Rhinopteridae, although this hypothesis requires direct behavioral and population level validation. These findings highlight the urgent need for a comprehensive taxonomic revision of the family, as well as a reassessment of current conservation strategies to better reflect the hidden diversity within this group of species.

International wildlife trade is a major source of biodiversity loss, yet many species lie hidden within aggregated data that conceals trade impacts. We overcome this problem for the largest vertebrate wildlife trade globally – shark and ray meat – comprising 438 538 mt yr-1 across more than 150 species, 76% of which are Threatened. Revealed trade contains greater quantities of skates (+10%), hammerheads (+8%), and smoothhounds, dogfishes & tope (+5%), and fewer pelagic sharks (-38%) than previously known. Shorttail yellownose skate, smoothound, silky, mako, and blue sharks are the most underreported meat species, due to aggregated landings from China, Argentina, Japan, and Indonesia, demonstrating international trade in shark and ray meat as a diverse, pervasive, and previously hidden source of fishing mortality for many threatened species. ### Competing Interest Statement The authors have declared no competing interest. Shark Conservation Fund

Despite the end of commercial whaling in 1972, the northern bottlenose whale ( Hyperoodon ampullatus ) remains endangered in Canada and faces multiple human threats. The effectiveness of marine protected areas (MPAs) in safeguarding highly mobile species like these whales is still unclear. We examined 35 years (1988–2023) of population trends in the Gully submarine canyon, off Canada's east coast and assessed spatial changes in human activities within protected and unprotected habitat on the Scotian Shelf. We analysed population size and habitat use using sighting rates and photo‐identification mark‐recapture data. We also evaluated whether spatial protections implemented through the designation of the Gully MPA in 2004 were associated with changes in the spatial distribution of threats, including ship strikes, entanglement, pollution and military sonar. We found the northern bottlenose whale population declined from 1988 until the mid‐2000s. However, from 2004 to 2010, coinciding with the establishment of spatial protections, this trend reversed, with the population growing near its maximum biological potential (~4% per year). Our analysis indicates that the intensity of two serious threats—commercial fishing and vessel traffic—has decreased within the highly protected Zone 1 area of the Gully MPA, where approximately 42% of the population can be found at any time. However, these activities now occur relatively more often in important habitat areas outside the MPA, indicating a spatial shift in fishing effort that raises concerns about potential displacement effects. Synthesis and applications . Spatial protection of the Gully MPA in 2004 coincided with a shift in human activities and the first signs of population recovery for northern bottlenose whales. While this suggests that well‐designed MPAs can contribute to conservation outcomes even for highly mobile species, long‐term success likely depends on continued monitoring and effective threat reduction both within the MPA and across other important habitats. Coordinated management across fisheries, shipping, offshore energy and defence sectors is essential. The Gully stands out as a rare conservation success in the open ocean, but its gains are not guaranteed.

Abstract The exceptional diversity of shallow‐water marine fishes contributes to the nutrition of millions of people worldwide through coastal wild‐capture fisheries, with different species having diverse nutritional profiles. Fishes in ecosystems are reservoirs of micronutrients with benefits to human health. Yet, the amount of micronutrients contained in fish species on coral reefs and in shallow tropical waters is challenging to estimate, and the micronutrients caught by fisheries remain uncertain. To assess whether micronutrient deficiencies could be addressed through specific fisheries management actions, we first require a quantification of the potentially available micronutrients contained in biodiverse reef fish assemblages. Here, we therefore undertake a broad heuristic assessment of available micronutrients on tropical reefs using ensemble species distribution modelling and identify potential mismatches with micronutrients derived from summarising coastal fisheries landings data. We find a mismatch between modelled estimates of micronutrients available in the ecosystem on the one hand and the micronutrients in small‐scale fisheries landings data. Fisheries had lower micronutrients than expected from fishes in the modelled assemblage. Further, fisheries were selective for vitamin A, thus resulting in a trade‐off with other micronutrients. Our results remained unchanged after accounting for the under‐sampling of fish communities and under‐reporting of small‐scale fisheries catches—two major sources of uncertainty. This reported mismatch indicates that current estimates of fished micronutrients are not adequate to fully assess micronutrient inventories. However, small‐scale fisheries in some countries were already selective towards micronutrient mass, indicating policies that target improved access, distribution and consumption of fish could leverage this existing high micronutrient mass. Enhanced taxonomic resolution of catches and biodiversity inventories using localised species consumption surveys could improve understanding of nature‐people linkages. Improving fisheries reporting and monitoring of reef fish assemblages will advance the understanding of micronutrient mismatches, which overall indicate a weak uptake of nutritional goals in fisheries practices. The decoupling between micronutrients in ecosystems and in fisheries catches indicates that social, economic, and biodiversity management goals are not shaped around nutritional targets—but this is key to achieve a sustainable and healthy planet for both people and nature. Read the free Plain Language Summary for this article on the Journal blog.

Chondrichthyans are a global conservation priority as populations of many species are increasingly overexploited and their derivative products are extensively traded. Liver oil is amongst the most widely used chondrichthyan product globally, however, information on trade and conservation efforts are often overshadowed by that of fins and meat. We used a mixed-method approach including a literature review, online surveys, and landing site surveys, and stakeholder interviews to describe the development of chondrichthyan liver oil markets in India, the species involved, current uses, and trade routes. Findings indicate that liver oil is one of the oldest utilized chondrichthyan derivative product in India, with demand for oil contributing to the retention and full utilization of many chondrichthyan species across Indian states. Markets have shifted from being centralised and industrial to diverse and cottage-based, with simple, artisanal production processes. This has created large and expanding markets for this versatile product within India, with at least 53 species contributing to the liver oil trade. We record a shift in use from large coastal to deepwater species as primary contributors to the liver oil trade. High-value liver oil is considered a primary product from incidentally caught and targeted deepwater species and is primarily exported. Low-value liver oil is a secondary derivative from pelagic and coastal sharks and rays and is mostly for domestic use. Considering the low rebound potential of deepwater chondrichthyan species, along with widespread population declines of pelagic and coastal species, we recommend management measures to monitor fisheries and regulate the expanding trade of chondrichthyan liver oil in India.

On shallow rocky and coral reefs, cultural and recreational values, like aesthetics, are critical aspects of Nature's Contributions to People (NCP) that support human well-being and provide billions of dollars in tourism revenue. Quantifying the aesthetic value of reef ecosystems and uncovering the conditions that enhance it could support NCP-based management. Here, we combine a global dataset of reef fish surveys, species-level aesthetic values, and causal modeling to assess the global status and drivers of reef fish assemblage aesthetic value. We find that aesthetic value is inherently linked to species richness, displaying a latitudinal gradient with peaks in the tropics, but varies strongly with the presence of exceptionally beautiful or less-beautiful species. Sea surface temperature, primary productivity, human gravity, and protection status are the strongest drivers of assemblage-level aesthetic value. Protection against human impacts consistently enhances aesthetic value by boosting taxonomic and phylogenetic diversity, and this effect is greatest in species-rich, tropical ecoregions. Economic development has little influence, indicating that low-income countries are not constrained from maintaining beautiful fish assemblages. Our results therefore suggest that marine protected areas (MPAs) can support multiple NCPs simultaneously, particularly in developing tropical countries. While we highlight the effectiveness of MPAs, given the low level of marine protection globally and the sensitivity of aesthetic value to environmental conditions, the beauty of the world's reefs appears severely threatened. Aesthetic value should be immediately integrated into reef conservation and management plans.

Many coral reefs have fish stocks that are depleted below the level at which sustainable production is maximized. Lower production means that millions of people are losing out on potential food, income, and livelihoods. Rebuilding these stocks to maximize sustainable production can contribute toward ending hunger and malnutrition but requires active and effective fisheries management. Yet, for fish stock recovery plans to be implemented, recovery benefits, targets, and timeframes need to be quantified. Here, using 1,211 individual reef sites and 23 jurisdictions identified globally as being below maximum sustainable production levels, we show that reefs have the potential to increase sustainable yields by nearly 50% if allowed to recover toward their maximum production levels. For individual jurisdictions, this recovery represents from 20,000 up to 162 million additional sustainable servings of reef fish per year in comparison to current sustainable production, meeting recommended seafood intake for up to 1.4 million additional people a year. However, such growth and food provisioning will require fish stocks to double their standing biomass (increase by a median of 32 t/km 2 ). Recovery timeframes range from 6.4 y under the most stringent scenario (a moratorium) to 49.7 y under the maximum harvest scenario that results in recovery. We find that locations with the greatest potential for sustainable gains in yield are among those with the greatest food and micronutrient deficiencies, underscoring both the challenges and opportunities in recovering fish assemblages to achieve their maximum sustainable potential.

Multispecies coral reef fisheries are typically managed by local communities who often lack research and monitoring capacity, which prevents estimation of well-defined sustainable reference points to perform locally relevant fishery assessments. Recent research modeling coral reef fisheries globally has estimated multispecies sustainable reference points (i.e., the maximum reef fish yields that can be harvested sustainably and the corresponding reef fish standing biomass at which those are expected to be achieved) based on environmental indicators. These global reference points are a promising tool for assessing data-poor reef fisheries but need to be downscaled to be relevant to resource practitioners. Using a small-scale multispecies reef fishery in Papua New Guinea, we estimated sustainable reference points and assessed the sustainability of the fishery by integrating global-scale analyses with local-scale environmental conditions (i.e., coral cover, sea surface temperature, ocean productivity, and whether the reef is an atoll), reef area, fish catch and standing biomass estimates, and fishers’ perceptions. Local-scale relevant data were obtained from a combination of remote sensing products, underwater visual censuses, catch surveys, and household structured social surveys. Our sustainability assessment based on downscaled estimated sustainable reference points was consistent with local fishers’ perceptions. Specifically, our downscaled results suggested that the fishing community was overfishing their reef fish stocks and stocks were below biomass levels that maximize production, making the overall reef fishery unsustainable. These results were consistent with fisher perceptions that reef fish stocks were declining in abundance and mean fish length and that fishers had to spend more time finding fish. Our downscaled site-level assessment revealed severe local resource exploitation, the dynamics of which were masked in national-scale assessments, emphasizing the importance of matching assessments to the scale of management. Overall, we show how global reference points can be applied locally when long-term data are not available, providing baseline assessments for sustainably managing previously unassessed multispecies reef fisheries around the globe.

Sharks have often been perceived to play a critical role in the dynamics of coral reef ecosystems globally. Yet, there is relatively little evidence to support this idea across all but a limited set of species and contexts. Research on the roles and importance of reef sharks has been complicated by logistical challenges in collecting data on sharks compounded by widespread declines in shark populations and reef state due to anthropogenic stressors. However, a better understanding of ecological roles is essential to uncover when, where, how, and to what degree sharks contribute to the function of coral reefs. To address this lack of understanding, we present a standardized framework for determining the ecological roles of reef sharks, including how different streams of data related to movement ecology, trophic ecology, demographics, and ecological context can be combined within specific functional components that collectively define the ecological roles of reef sharks. A series of steps and questions are used to guide research on individual species and promote collection of necessary data. We explore what data in real-world examples can mean for uncovering roles and how data can be interpreted from a functional perspective. Although the framework is centred around breaking down ecological roles into simpler components, it forces researchers to complete a comprehensive evaluation of the animal's ecology and consider how data from each of these components complements each other in a broader context. The need for a detailed and directed approach for researchers to explore the mechanisms, patterns, and causes that comprise reef shark ecological roles is supported by a literature review showing expansive knowledge gaps that persist for most coral-reef-resident and smaller-bodied species. Existing research on the movement and trophic ecology of reef sharks is diverse and spans a broad range of topics and contexts, indicating potential for combining and re-evaluating existing data to improve current knowledge of roles. Resident species with relatively large amounts of published research included grey reef (Carcharhinus amblyrhynchos), blacktip reef (Carcharhinus melanopterus), and whitetip reef sharks (Triaenodon obesus), which are among the most widely abundant sharks on coral reefs. As ongoing changes to coral reefs may alter rates of ecological processes, understanding the roles and importance of reef sharks will be crucial to predicting future reef states and enacting effective conservation and management strategies to preserve key functions.

Marine protected areas (MPAs) are widely used to conserve and manage coastal resources. Protected areas are governed by a variety of institutional arrangements, yet little is known concerning the relative performance of different governance approaches. This research draws upon a unique dataset that combines details on the reported International Union for Conservation of Nature (IUCN) governance categories of 217 global MPAs and their ecological outcomes to compare the performance of alternative governance arrangements. We find that MPAs with shared governance arrangements, where management authority is shared among multiple government and non-government actors, are 98% more likely to have higher fish biomass than MPAs governed by state agencies (i.e., primarily government) alone (mean effect size and 95% C.I = 0.32 ± 0.31). We also find higher biomass in older MPAs, those in countries with higher gross domestic product (GDP), and those with a higher proportion of no-take area. With targets to protect 30% of our oceans driving new commitments to expand MPA coverage globally, our results suggest that multi-stakeholder participation and collaboration facilitated by shared and decentralized governance arrangements can play an important role in achieving conservation outcomes.

Many shark populations are in decline around the world, with severe ecological and economic consequences. Fisheries management and marine protected areas (MPAs) have both been heralded as solutions. However, the effectiveness of MPAs alone is questionable, particularly for globally threatened sharks and rays (‘elasmobranchs’), with little known about how fisheries management and MPAs interact to conserve these species. Here we use a dedicated global survey of coral reef elasmobranchs to assess 66 fully protected areas embedded within a range of fisheries management regimes across 36 countries. We show that conservation benefits were primarily for reef-associated sharks, which were twice as abundant in fully protected areas compared with areas open to fishing. Conservation benefits were greatest in large protected areas that incorporate distinct reefs. However, the same benefits were not evident for rays or wide-ranging sharks that are both economically and ecologically important while also threatened with extinction. We show that conservation benefits from fully protected areas are close to doubled when embedded within areas of effective fisheries management, highlighting the importance of a mixed management approach of both effective fisheries management and well-designed fully protected areas to conserve tropical elasmobranch assemblages globally. A survey of sharks and rays on coral reefs within 66 marine protected areas across 36 countries showcases that the conservation benefits of full MPA protection to sharks almost double when accompanied by effective fisheries management.

Coral reefs support an incredible abundance and diversity of fish species, with reef-associated fisheries providing important sources of income, food, and dietary micronutrients to millions of people across the tropics. However, the rapid degradation of the world's coral reefs and the decline in their biodiversity may limit their capacity to supply nutritious and affordable seafood while meeting conservation goals for sustainability. Here, we conduct a global-scale analysis of how the nutritional quality of reef fish assemblages (nutritional contribution to the recommended daily intake of calcium, iron, and zinc contained in an average 100 g fish on the reef) relates to key environmental, socioeconomic, and ecological conditions, including two key metrics of fish biodiversity. Our global analysis of more than 1,600 tropical reefs reveals that fish trophic composition is a more important driver of micronutrient concentrations than socioeconomic and environmental conditions. Specifically, micronutrient density increases as the relative biomass of herbivores and detritivores increases at lower overall biomass or under high human pressure. This suggests that the provision of essential micronutrients can be maintained or even increase where fish biomass decreases, reinforcing the need for policies that ensure sustainable fishing, and that these micronutrients are retained locally for nutrition. Furthermore, we found a negative association between micronutrient density and two metrics of fish biodiversity, revealing an important nutrition-biodiversity trade-off. Protecting reefs with high levels of biodiversity maintains key ecosystem functions, whereas sustainable fisheries management in locations with high micronutrient density could sustain the essential supply of micronutrients to coastal human communities.

Overfishing, as well as habitat loss and degradation, has led to major population declines and local extinctions of sawfishes (Pristidae) globally. Four sawfish species reportedly occur in India; however, records have been limited to opportunistic commercial catch and landing reports. Here, we provide the first comprehensive review of published and grey literature on sawfish records from India, including opportunistic observations of sawfish rostra offerings to religious places, highlighting the cultural significance of these species locally. In total, 223 recorded capture events were compiled between 1794 and 2022, with largetooth sawfish Pristis pristis (n = 82), followed by narrow sawfish Anoxypristis cuspidata (n = 32), being the dominant species reported. In addition to marine fisheries, 8 reports of sawfish were reported from freshwater systems. The wide range of rostra sizes and total lengths recorded also suggests that India’s waters harbour various life history stages of sawfish. When caught, sawfish livers were utilised to produce oil, meat was locally consumed, and fins were exported. Despite being legally protected in India since 2001, 63 incidental captures were recorded from landings, suggesting various levels of awareness and enforcement of catch bans across the country. To avoid extinction of these species in India, we emphasise the need to conduct culturally associated awareness programs with coastal communities, encourage safe release and improve handling practices with fishers, identify critical habitats, and strengthen enforcement for mandatory live release.

In ecosystems, sharks can be predators, competitors, facilitators, nutrient transporters, and food. However, overfishing and other threats have greatly reduced shark populations, altering their roles and effects on ecosystems. We review these changes and implications for ecosystem function and management. Macropredatory sharks are often disproportionately affected by humans but can influence prey and coastal ecosystems, including facilitating carbon sequestration. Like terrestrial predators, sharks may be crucial to ecosystem functioning under climate change. However, large ecosystem effects of sharks are not ubiquitous. Increasing human uses of oceans are changing shark roles, necessitating management consideration. Rebuilding key populations and incorporating shark ecological roles, including less obvious ones, into management efforts are critical for retaining sharks’ functional value. Coupled social-ecological frameworks can facilitate these efforts.

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our specieslevel analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities.

Ecologists are often interested in answering causal questions from observational data but generally lack the training to appropriately infer causation. When applying statistical analysis (e.g., generalized linear model) on observational data, common statistical adjustments can often lead to biased estimates between variables of interest due to processes such as confounding, overcontrol, and collider bias. To overcome these limitations, we present an overview of structural causal modeling (SCM), an emerging causal inference framework that can be used to determine cause-and-effect relationships from observational data. The SCM framework uses directed acyclic graphs (DAGs) to visualize researchers' assumptions about the causal structure of a system or process under study. Following this, a DAG-based graphical rule known as the backdoor criterion can be applied to determine statistical adjustments (or lack thereof) required to determine causal relationships from observational data. In the presence of unobserved confounding variables, an additional rule called the frontdoor criterion can be employed to determine causal effects. Here, we use simulated ecological examples to review how the backdoor and frontdoor criteria can return accurate causal estimates between variables of interest, as well as how biases can arise when these criteria are not used. We further provide an overview of studies that have applied the SCM framework in ecology. SCM, along with its application of DAGs, has been widely used in other disciplines to make valid causal inferences from observational data. Their use in ecology holds tremendous potential for quantifying causal relationships and investigating a range of ecological questions without randomized experiments.