Partitioning critical resources can alleviate competition among species, allow coexistence, and contribute to biodiversity. The mechanisms driving habitat partitioning within the small-bodied and highly diverse genus Trimma remain unclear. The main aim of this study was to uncover habitat use and partitioning of T. benjamini, T. capostriatum, and T. yanoi that may enable their coexistence on coral reefs in Kimbe Bay, Papua New Guinea, using a combination of active visual search transects and behavioural observations. The spatial distributions of each species were distinct. Reef aspect played a significant role, with T. yanoi and T. benjamini being most abundant on the reef wall, while T. capostriatum predominantly favoured the reef slope at offshore locations. Generally, there were variations in abundance among depths in all species, though there were exceptions for specific reef aspects. Reef location (inshore vs. offshore) influenced the distribution of T. capostriatum, but not T. benjamini or T. yanoi. Population clustering was also examined. T. yanoi formed the largest clusters of 9 individuals on average, followed by T. benjamini with 7 individuals on average. T. yanoi clusters had 1.5 times the population density per m2 quadrat compared to T. benjamini. In contrast, T. capostriatum exhibited the smallest cluster sizes and densities, with the highest proportion (30

Smaller animals may have an enhanced ability to convert microscopic food into biomass, a form of energy that is accessible to larger predators. Small-bodied cryptobenthic reef fishes (CRFs) exploit a variety of small food items and may themselves be important food sources for other coral reef dwellers. However, knowledge regarding the trophic niches of small and abundant CRFs of the genus Trimma is lacking. The aim of this study was to investigate the trophic dynamics of Trimma benjamini, T. capostriatum, and T. yanoi by examining their feeding behaviour, food items consumed, food origins (benthic or pelagic), trophic interactions, and ecological morphology. The majority of individuals (79.7–93.4

Some individual coral colonies can grow to immense sizes and survive for centuries, offering rare insight into how corals persist over long time scales. This study documents one of the largest coral colonies ever recorded-a colossal Pavona clavus in Tonga-and shows that, despite being dominated by a single species, it supports fish communities and ecosystem functions comparable to typical nearby reefs. These findings suggest that giant coral colonies may play an important role as resilient habitats and potential refuges in a changing ocean.

Somatic growth influences survival and reproduction, with flow-on effects on population dynamics and energy fluxes within ecosystems. Small-bodied cryptobenthic reef fishes may contribute significantly to productivity due to their life-history traits, including growth rates and rapid generational turnover. However, comprehensive studies on growth that encompass all stages of life are rare. This study aimed to investigate growth patterns across life-history stages and generational turnover rates in three Trimma species that are abundant on coral reefs in the Pacific: Trimma benjamini, Trimma capostriatum and Trimma yanoi. The Trimma species examined exhibited small body sizes of <25 mm and short life spans of <140 days, potentially enabling them to produce over three generations annually. Three growth models were compared (Modified Fry model, Body Proportional Hypothesis, and the Biological Intercept model) to back-calculate growth at ages prior to capture, and the Body Proportional Hypothesis performed the best in each species, indicated by the lowest residual sum of squares and mean squared error of the model. Each species displayed similar growth patterns, with growth rates varying across different life-history stages. Growth was most rapid during the pelagic larval phase, averaging 0.2 mm per day. The size at settlement was small, ranging from 7.6 to 8.4 mm. Growth was initially rapid post-settlement but gradually slowed, averaging 0.16 to 0.17 mm per day during the juvenile stage. In the adult phase, growth was non-asymptotic, averaging approximately 0.15 mm per day, with 31.3%-37.0% of total growth occurring during this stage. Growth decreased by 8.6%-11.7% following maturation, which is minor compared to the patterns observed in larger fish species. These findings support the expanding literature, suggesting cryptobenthic reef fishes exhibit unique life-history traits that could be associated with their small maximum body size.

To ensure the protection of both people and nature, conservation practitioners have a responsibility to integrate human rights considerations into their conservation policies and practices. Here, we (i) develop a human rights-based scoring framework for international conservation organization (NGO) policy commitments and (ii) use this to conduct a gap analysis of policy commitments for nine NGOs, which collectively contribute approximately $1.86 billion USD annually to the global conservation budget.While progress has been made, critical gaps remain in commitments to certain rights and recognizing local groups' rights and knowledge, particularly around social development and decent work, recognitional equity, and commitments to implement human rights-based approach principles. Given the influence of these organizations in global public discourse, more comprehensive public commitments to human rights will likely increase compliance with international law, drive organizational change, and help rebuild trust with vulnerable communities.

Tonga’s Special Management Areas (SMAs) have been widely supported by the people of Tonga as a successful approach to the comanagement of their fisheries and marine resources. However, due to the dominant focus on expansion of the program over recent years, challenges remain for the effective and consistent monitoring and evaluation needed to understand program impacts. This review compiles all known ecological, fisheries, and socio-economic monitoring and evaluation reports related to Tonga’s Special Management Areas from 2010 onwards. A total of 25 projects with available reports were identified, with most examining ecological (42%) and socio-economic (42%) aspects of SMAs, whereas reporting on SMA fisheries data (e.g. catch) was limited to five available projects. Most studies also represented ‘baseline’ ecological and socio-economic surveys of SMAs during implementation. Only three studies have assessed the ecological impact of SMAs post intervention, and only one of these incorporated ‘follow-up’ surveys at a second time point. Among these, impacts remain mixed, with some SMAs resulting in larger and more abundant fish, but others showing no impact. Other monitoring challenges include no gender disaggregation of data, no monitoring of gleaning, haphazard monitoring by communities, and general concerns of cost, fit for purpose, and overinvestment. Although the limited available ecological data indicates that SMAs can increase fish size and abundance in some cases, rationalised, more efficient, and targeted monitoring is required to better understand and strengthen the functioning of SMAs and inform community and government management decisions.

Human rights matter for marine conservation because people and nature are inextricably linked. A thriving planet cannot be one that contains widespread human suffering or stifles human potential; and a thriving humanity cannot exist on a dying planet. While the field of marine conservation is increasingly considering human well-being, it retains a legacy in some places of protectionism, colonialism, and fortress conservation. Here, we i) provide an overview of human rights principles and how they relate to marine conservation, ii) document cases where tensions have occurred between marine conservation goals and human rights, iii) review the legal and ethical obligations, and practical benefits, for marine conservation to support human rights, and iv) provide practical guidance on integrating human rights principles into marine conservation. We argue that adopting a human rights-based approach to marine conservation, that is integrating equity as a rights-based condition rather than a charitable principle, will not only help meet legal and ethical obligations to respect, protect, and fulfil human rights, but will also result in greater and more enduring conservation impact.

Advocates, practitioners and policy-makers continue to use and advocate for marine protected areas (MPAs) to meet global ocean protection targets. Yet many of the worlds MPAs, and especially no-take MPAs, are plagued by poaching and ineffective governance. Using a global dataset on coral reefs as an example, we quantify the potential ecological gains of governing MPAs to increase compliance, which we call the 'compliance gap'. Using ecological simulations based on model posteriors of joint Bayesian hierarchical models, we demonstrate how increased compliance in no-take MPAs could nearly double target fish biomass (91% increases in median fish biomass), and result in a 292% higher likelihood of encountering top predators. Achieving these gains and closing the compliance gap necessitates a substantial shift in approach and practice to go beyond optimizing enforcement, and towards governing for compliance. This will require engaging and integrating a broad suite of actors, principles, and practices across three key domains: (i)) harnessing social influence, (ii) integrating equity principles, and (iii) aligning incentives through market-based instruments. Empowering and shaping communication between actor groups (e.g., between fishers, practitioners, and policy-makers) using theoretically underpinned approaches from the behavioural sciences is one of the most essential, but often underserved aspects of governing MPAs. We therefore close by highlighting how this cross-cutting tool could be further integrated in governance to bolster high levels of compliance in MPAs.

Data and code necessary for reproducing analyses, results and figures from Morais et al. 'Sustained productivity and the persistence of coral reef fisheries', Nature Sustainability. Compressed file includes: Data: folder with data files used for the analyses; Mod_Out: folder with critical model outputs to steer the analyses without having to undergo lengthy model selection; Outputs: empty folder where figures and tables will be generated; Outputs_authors: as the name suggests, includes the Outputs as last generated by the authors on 27 March 2023; Scripts: individual R scripts for the main analyses, results, figures; Sensitivity: individual R-Markdown documents and data required to run Supplementary Analyses 1 and 2 of the manuscript; Morais_et_al_RUN.R: master script for reproducing the analyses. Running this file automatically loads all data files and executes code that creates and saves figures and tables.

Small-scale fisheries account for 90% of global fishers and 40% of the global catch. Effectively managing small-scale fisheries is, therefore, crucial to progressing the United Nations Sustainable Development Goals (SDGs). Co-management and community-based fisheries management are widely considered the most appropriate forms of governance for many small-scale fisheries. We outlined relationships between small-scale fisheries co-management and attainment of the SDGs, including evidence for impacts and gaps in dominant logic. We identified 11 targets across five SDGs to which small-scale fisheries co-management (including community-based fisheries management) can contribute; the theory of change by which these contributions could be achieved; and the strength of evidence for progress toward SDG targets related to various co-management strategies. Our theory of change links the 11 SDG targets by qualifying that progress toward some targets is contingent on others being achieved first. We then reviewed 58 case studies of co-management impacts from the Pacific Islands--a region rich in local marine governance--to evaluate evidence of where, to what degree, and with how much certainty different co-management strategies conferred positive impacts to each SDG target. These strategies included access restrictions, permanent area closures, periodic closures, and gear and species restrictions. Although many studies provide evidence linking multiple co-management strategies to improvements in resource status (SDG 14.4), there was limited evidence of follow-on effects, such as improvements in catch (SDG 2.3, 2.4), livelihoods (SDG 1.2), consumption (SDG 2.1), and nutrition (SDG 2.2). Our findings suggest that leaps of logic and assumptions are prevalent in co-management planning and evaluation. Hence, when evaluating co-management impacts against the SDGs, consideration of ultimate goals is required, otherwise, there is a risk of shortfalls between aspirations and impact.

Effective management of depleted natural resources can be achieved only through changes in human actions. Opportunity costs represent the forgone benefits that would have flowed in the absence of conservation interventions. To the extent that opportunity costs reflect lost opportunities for extractive uses (e.g., fishing or logging), and to the extent that those extractive uses present threats to nature, opportunity costs therefore reflect the positive differences for natural values that can be made through conservation management. Thus, logic dictates that, if conservationists make choices to minimize opportunity costs, they are also necessarily limiting their impact. Unfortunately, empirical evidence from many conservation contexts implies that conservationists indeed make choices consistent with an aim to minimize opportunitycosts, and hence impact. A better understanding of the relationship between opportunity costs and conservation impact will make the language used to communicate conservation progress, targets, and planning more honest and accountable and more explicitly focused on the differences our actions make.

Body size influences many life-history traits, with small-bodied animals tending to have short life spans, high mortality and greater reproductive effort early in life. In this study, the authors investigated the life-history traits and reproductive strategies of three small-bodied coral reef gobies of the genus Trimma: Trimma benjamini, Trimma capostriatum and Trimma yanoi. The authors found all Trimma species studied attained a small body size of <25 mm, had a short life span of <140 days and experienced high estimated daily mortality of 3.0%-6.7%. Furthermore, the pelagic larval phase accounted for 25.3%-28.5% of the maximum life span, and maturation occurred between 74.1 and 82.1 days at 15.2-15.8 mm, leaving only 35%-43% of the total life span as a reproductively viable adult. All mature individuals had gonad structures consistent with bidirectional sex change, with bisexual gonads including both ovarian and testicular portions separated by a thin wall of connective tissue. In the female and male phases, only ovaries or testes were mature, whereas gonadal tissue of the non-active sex remained. One T. benjamini individual and one T. yanoi individual had ovarian and testicular tissue active simultaneously. The results of this study highlight the life-history challenges small CRFs face on their path to reproduction and reproductive strategies that could be beneficial in fishes with high and unpredictable mortality and short reproductive life spans.

Partially protected areas are now the dominant global form of spatial management aimed at preserving ecosystem integrity and managing human use. However, most evaluations of their efficacy use only a narrow set of conservation indicators that reflect a fraction of ways in which protection can succeed or fail. In this paper, we examine three case studies of partially protected coral reef fishery systems to evaluate benefits and risks of their use as a management tool. We use data from community-based management arrangements in three Pacific Island countries to demonstrate three vignettes of how partial protection can boost fisheries production, enhance the ease with which fishers catch their prey, and alter the composition of fisheries yields. These changes in fisheries productivity, catchability, and vulnerability under partial protection carry substantial benefits for fishers. However, they also carry significant risks for ecosystems and fisheries livelihoods unless adaptively managed so as to confer the short to medium term benefits in resource performance without risking longer term sustainability.

Co-management, a governance process whereby management responsibility is shared between resource users and other collaborators, is a mainstream approach for governing social and ecological aspects of small-scale fisheries. While many assessments of co-management are available for single time periods, assessments across longer time-scales are rare–meaning the dynamic nature, and long-term outcomes, of co-management are insufficiently understood. In this study we analyse ten-years of catch and effort data from a co-managed, multi-species reef fishery in Solomon Islands. To further understand social, ecological and management dynamics we also draw on interviews with fishers and managers that had been conducted throughout the same decade. We aimed to answer (1) what are the temporal trends in fishing effort, harvesting efficiency, and catch composition within and beyond a periodically-harvested closure (i.e. a principal and preferred management tool in Pacific island reef fisheries), and, (2) what are the internal and external drivers that acted upon the fishery, and its management. Despite high fishing effort within the periodically-harvested closure, catch per unit effort remained stable throughout the ten years. Yet the taxonomic composition of catch changed substantially as species targeted early in the decade became locally depleted. These observations indicate that both the frequency of harvesting and the volumes harvested may have outpaced the turnover rates of target species. We argue that this reflects a form of hyperstability whereby declining abundance is not apparent through catch per unit effort since it is masked by a shift to alternate species. While the community sustained and adapted their management arrangements over the decade as a response to internal pressures and some signs of resource changes, some external social and ecological drivers were beyond their capabilities to govern. We argue the collaborative, knowledge exchange, and learning aspects of adaptive co-management may need even more attention to deal with this complexity, particularly as local and distal pressures on multi-species fisheries and community governance intensify. Graphical abstract

Coastal fisheries are a critical component of Pacific island food systems; they power village economies and provide nutritious aquatic foods. Many coastal women and men actively fishing in this region rely on multi-species fisheries, which given their extraordinary diversity are notoriously difficult to both characterize, and to manage. Understanding patterns of fishing, diversity of target species and drivers of these patterns can help define requirements for sustainable management and enhanced livelihoods. Here we use a 12-month data set of 8535 fishing trips undertaken by fishers across Malaita province, Solomon Islands, to create fisheries signatures for 13 communities based on the combination of two metrics; catch per unit effort (CPUE) and catch trophic levels. These signatures are in turn used as a framework for guiding suitable management recommendations in the context of community-based resource management. While a key proximate driver of these patterns was fishing gear (e.g. angling, nets or spearguns), market surveys and qualitative environmental information suggest that community fishing characteristics are coupled to local environmental features more than the market value of specific species they target. Our results demonstrate that even within a single island not all small-scale fisheries are equal, and effective management solutions ultimately depend on catering to the specific environmental characteristics around individual communities.

Coral reefs are the epitome of species diversity, yet the number of described scleractinian coral species, the framework-builders of coral reefs, remains moderate by comparison. DNA sequencing studies are rapidly challenging this notion by exposing a wealth of undescribed diversity, but the evolutionary and ecological significance of this diversity remains largely unclear. Here, we present an annotated genome for one of the most ubiquitous corals in the Indo-Pacific (Pachyseris speciosa) and uncover, through a comprehensive genomic and phenotypic assessment, that it comprises morphologically indistinguishable but ecologically divergent lineages. Demographic modeling based on whole-genome resequencing indicated that morphological crypsis (across micro- and macromorphological traits) was due to ancient morphological stasis rather than recent divergence. Although the lineages occur sympatrically across shallow and mesophotic habitats, extensive genotyping using a rapid molecular assay revealed differentiation of their ecological distributions. Leveraging “common garden” conditions facilitated by the overlapping distributions, we assessed physiological and quantitative skeletal traits and demonstrated concurrent phenotypic differentiation. Lastly, spawning observations of genotyped colonies highlighted the potential role of temporal reproductive isolation in the limited admixture, with consistent genomic signatures in genes related to morphogenesis and reproduction. Overall, our findings demonstrate the presence of ecologically and phenotypically divergent coral species without substantial morphological differentiation and provide new leads into the potential mechanisms facilitating such divergence. More broadly, they indicate that our current taxonomic framework for reef-building corals may be scratching the surface of the ecologically relevant diversity on coral reefs, consequently limiting our ability to protect or restore this diversity effectively.

Environmental conditions can strongly influence the growth performance of pearl oysters and affect pearl farm production schedules. Growth and condition index (CI) of two age cohorts of Pteria penguin were measured for 13 months to investigate differences in growth performance between four culture sites within the northern (Vava’u) and southern (Tongatapu) island groups of the Kingdom of Tonga. Environmental conditions were also measured at culture sites and used to explore potential effects on oyster growth and condition. Between island groups, growth performance of P. penguin was superior at northern sites and was most strongly related to higher water temperatures at these sites. Within the southern island group, growth performance varied significantly between sites and may be driven by differences in wave energy. Monthly growth rates (GM) of P. penguin also showed significant temporal variation related to age and environmental conditions. This study demonstrated significant variation in the growth performance of P. penguin at latitudinal and local scales and suggests that in oligotrophic marine environments with minimal terrestrial inputs, such as Tonga, water temperature and wave exposure may be the primary environmental conditions influencing the growth performance of P. penguin. This study therefore recommends that optimal culture sites for P. penguin in Tonga are characterized primarily by warmer water temperatures (25–30°C) and low wave exposure (<15 joules m2 day–1). Culture of P. penguin at sites with more suitable environmental conditions enables pearl production to begin up to 34.2 % (6.5 months) earlier than at less-suitable sites and this may greatly influence mabé pearl farm profitability and feasibility.

Environmental conditions and anthropogenic impacts are key influences on ecological processes and associated ecosystem services. Effective management of Tonga's marine ecosystems therefore depends on accurate and up-to-date knowledge of environmental and anthropogenic variables. Although many types of environmental and anthropogenic data are now available in global layers, they are often inaccessible to end users, particularly in developing countries with limited accessibility and analytical training. Furthermore, the resolution of many global layers might not be sufficient to make informed local decisions. Although the near-shore marine ecosystem of Tonga is extensive, the resources available for its management are limited, and little is known about its current ecological state. Here we provide a marine socio-environmental dataset covering Tonga's near-shore marine ecosystem as compiled from various global layers, remote sensing projects, local ministries, and the 2016 national census. The dataset consists of 11 environmental and 6 anthropogenic variables summarised in ecologically relevant ways, spatially overlaid across the near-shore marine ecosystem of Tonga. The environmental variables selected include bathymetry, coral reef density, distance from deep water, distance from land, distance from major terrestrial inputs, habitat, land area, net primary productivity, salinity, sea surface temperature and wave energy. The anthropogenic variables selected include fishing pressure, management status, distance to fish markets, distance from villages, population pressure and a socioeconomic development index based on population density, growth, mean age, mean education level and unemployment. We hope this extensive and accessible dataset will be a useful tool for future assessment and management of marine ecosystems in Tonga.

Spatial subsidies increase local productivity and boost consumer abundance beyond the limits imposed by local resources. In marine ecosystems, deeper water and open ocean subsidies promote animal aggregations and enhance biomass that is critical for human harvesting. However, the scale of this phenomenon in tropical marine systems remains unknown. Here, we integrate a detailed assessment of biomass production in 3 key locations, spanning a major biodiversity and abundance gradient, with an ocean-scale dataset of fish counts to predict the extent and magnitude of plankton subsidies to fishes on coral reefs. We show that planktivorous fish-mediated spatial subsidies are widespread across the Indian and Pacific oceans and drive local spikes in biomass production that can lead to extreme productivity, up to 30 kg ha-1 day-1. Plankton subsidies form the basis of productivity "sweet spots" where planktivores provide more than 50% of the total fish production, more than all other trophic groups combined. These sweet spots operate at regional, site, and smaller local scales. By harvesting oceanic productivity, planktivores bypass spatial constraints imposed by local primary productivity, creating "oases" of tropical fish biomass that are accessible to humans.