Small pelagic fish supply abundant and affordable micronutrients to low- and middle-income countries

Impacts of Belo Monte dam on fish co-occurrence and artisanal fishing

The operation of large hydroelectric dams, such as Belo Monte in the Brazilian Amazon, significantly disrupts local freshwater ecosystems, impacting the socio-economic fabric and food security of dependent communities. To investigate and simulate future dam-induced impacts on fish species crucial for subsistence and artisanal fishing, this study leveraged subsistence fishing data from four areas of the Xingu River: the reservoir, upstream, the de-watered reach, and downstream. Using network analysis and graph theory, we examined the temporal and spatial variations in fish species composition, focusing on species that co-occur in fishing catches and their ecological roles within the network. Results showed a 34 % reduction in total biomass, from 8442.51 kg (2012-2015) to 5537.42 kg (2016-2020). The analysis revealed marked changes in species diversity and catch composition, with substantial shifts in heavily altered regions. For instance, in the de-watered reach, traditional species such as curimatã (Prochilodontidae) were replaced by others like pacu (Serrasalmidae), reflecting ecological shifts and the replacement of a detritivorous species by an omnivorous one. Directed simulations projected the dynamics of species loss, revealing significant alterations in co-occurrence patterns and network centrality, particularly in the de-watered reach. These simulations demonstrated that species such as pacu, pescada (Sciaenidae), and tucunaré (Cichlidae) remained central to the network despite ongoing ecological transformations. While this study provides valuable insights into environmental shifts, the absence of direct socio-economic data highlights the need for future research to understand the broader impacts on artisanal fisheries better. These results underscore the profound transformations in fish diversity and emphasize the critical need for adaptive management strategies to mitigate these impacts, ensuring the resilience of local fishing communities. While our findings offer valuable ecological insights, the absence of direct socio-economic data highlights the need for future research to better understand the broader impacts of hydroelectric dams on artisanal fisheries.

Predicting essential and hazardous element concentrations in marine fish from the Northeast Atlantic Ocean: A Bayesian approach

Micronutrient deficiency or 'hidden hunger' is of growing importance regionally and globally. Marine fish have the potential to mitigate hidden hunger although certain contaminants they often contain may also pose a health risk. Understanding biological and environmental drivers behind essential and hazardous element concentrations is therefore important to develop evidence-based advice for adaptive management strategies. We use Bayesian models to predict concentrations of ten essential and two hazardous elements in fillets of 14 marine fish species in the Northeast Atlantic Ocean. Data from 15,709 individuals of six lean, five semi-fatty, and three fatty species were included. Fish length, fat content, ocean basin, sea temperature and salinity were used as predictor variables. We found good model predictability and identified some important trends in driver effects. Fish length was the most important driver of element concentrations for most species with a negative effect for calcium, copper, manganese, and arsenic, and a positive effect for mercury, suggesting that smaller individuals may be a safer and better source of essential elements. Ocean basin was also an important driver in most cases. For concentrations of selenium, zinc, and mercury, effect sizes of ocean basins increased from north to south for several species. Fat content exhibited a small negative effect on concentrations of calcium, iron, and mercury, and a small positive effect on phosphorus and arsenic concentrations in many species. Temperature showed a small negative effect on zinc concentration for most species, while the effect of salinity varied among species without an apparent trend. This is the first multi-species and multi-element study to investigate drivers of element concentrations in marine fish at a large spatial scale using a Bayesian approach. The robust model predictability indicates the models' potential to further understand nutrient yield dynamics from fisheries, thereby empowering the implementation of informed strategies against hidden hunger.

Seafood supply mapping reveals production and consumption mismatches and large dietary nutrient losses through exports in the United Kingdom

Seafood can contribute towards healthy and sustainable food systems by improving public health and helping achieve net zero carbon emissions. Here, we provide a high-resolution perspective on UK seafood supplies and nutrient flows at the species level. We mapped seafood production (capture and aquaculture), trade (imports and exports), purchases (within and out of home) and seafood consumption between 2009 and 2020. UK dietary recommendations for finfish consumption were not achieved by domestic production nor national supplies. Mapping dietary nutrient flows revealed that the UK undergoes substantial losses of omega-3 fatty acids, vitamin B12 and vitamin D, which could contribute 73%, 46% and 7% towards UK-recommended nutrient intakes, respectively, through exports of oily fish such as salmon, herring and mackerel. Policies should consider promoting greater consumption of locally produced oily fish species to improve public health and seafood system resilience.

China's municipal wastewater policies enhanced seafood safety and offset health risks from atmospheric mercury emissions in the past four decades

The neurotoxin methylmercury in seafood threatens food safety worldwide. China has implemented stringent wastewater policies, established numerous treatment facilities and enforced rigorous water quality standards to address pollution in its waterways. However, the impact of these policies on seafood safety and methylmercury exposure remains unknown. Here we developed a process-based model showing that, although mercury reductions from municipal wastewater policies accounted for only 9% of atmospheric mercury emissions during 1980-2022, these measures unexpectedly prevented102,000 - 6,600 + 11,000 mercury-related deaths and counteracted nearly two thirds of potential deaths from those emissions. Furthermore, these policies ensured that146 - 9 + 8 megatonnes of freshwater seafood met the World Health Organization and China's mercury-safety standards, preventing US $ 498 - 29 + 32 billion in economic losses. Finally, we explore how China, as the primary global seafood producer and exporter, could develop municipal wastewater policies at the regional level to reduce aquatic pollutants and unlock the health benefits of seafood consumption.

Food, power and agency: revealing local post-harvest fisheries practices to improve food access from small-scale fisheries in coastal Kenya

This article proposes the case of Kenyan coastal fisheries as a potentially crucial reservoir of food-related benefits for the marginalised and those living in poverty, but where a food-centred lens or approach is seldom mainstreamed in local and national governance. Borrowing insights from post-structuralist marine social sciences, this article presents an ethnographic account of grassroots practices in-the-making such as handling, sorting, and allocating fish once caught, and how these practices lead to local categorisations and classifications of fish. This sort of evidence and knowledge around local categorisations and classifications of fish spotlights the importance of considering the post-harvest sector (as opposed to the activity of fishing alone), that is, how the use of catch determines access through micro relations of power and agency. Through the analysis of two different locations of Watamu and Shimoni in terms of the fisheries economy and overall development, the analysis of these categories and classifications highlights the necessity to account for a fairer access and distribution rather than solely production (of fish) that is overly market-oriented.

Illuminating the multidimensional contributions of small-scale fisheries

Sustainable development aspires to "leave no one behind"1. Even so, limited attention has been paid to small-scale fisheries (SSF) and their importance in eradicating poverty, hunger and malnutrition. Through a collaborative and multidimensional data-driven approach, we have estimated that SSF provide at least 40% (37.3 million tonnes) of global fisheries catches and 2.3 billion people with, on average, 20% of their dietary intake across six key micronutrients essential for human health. Globally, the livelihood of 1 in every 12 people, nearly half of them women, depends at least partly on small-scale fishing, in total generating 44% (US$77.2 billion) of the economic value of all fisheries landed. Regionally, Asian SSF provide fish, support livelihoods and supply nutrition to the largest number of people. Relative to the total capture of the fisheries sector (comprising large-scale and small-scale fisheries), across all regions, African SSF supply the most catch and nutrition, and SSF in Oceania improve the most livelihoods. Maintaining and increasing these multidimensional SSF contributions to sustainable development requires targeted and effective actions, especially increasing the engagement of fisherfolk in shared management and governance. Without management and governance focused on the multidimensional contributions of SSF, the marginalization of millions of fishers and fishworkers will worsen.

Meta-analysis of the effects of microplastic on fish: Insights into growth, survival, reproduction, oxidative stress, and gut microbiota diversity

Aquatic ecosystems are primary repositories for microplastics (MPs), which pose significant risks to aquatic organisms. This study addresses the gap in understanding the effects of MPs pollution by analyzing 3,757 biological endpoints from 85 laboratory studies. Overall, our results indicate that MPs exposure significantly inhibits fish growth, survival, and reproductive ability, and increases oxidative damage, specifically, MPs exposure leads to elevated levels of malondialdehyde. However, MPs do not have a significant impact on the diversity of fish gut microbiota. Subgroup and correlation analyses indicate that the extent of various toxic effects is influenced by multiple factors, including MPs' type, exposure pathway, size, concentration, as well as the aquatic environment or life stage of the fish. In addition, the regression analysis revealed a relationship between the magnitude of toxic effects and the size, concentration, or duration of MPs exposure. This study provides useful information for understanding the potential impacts of MPs on aquatic organisms and offers new insights for the protection and management of aquatic ecosystems.

Linking extinction risk to the economic and nutritional value of sharks in small-scale fisheries

To achieve sustainable shark fisheries, it is key to understand not only the biological drivers and environmental consequences of overfishing, but also the social and economic drivers of fisher behavior. The extinction risk of sharks is highest in coastal tropical waters, where small-scale fisheries are most prevalent. Small-scale fisheries provide a critical source of economic and nutritional security to coastal communities, and these fishers are among the most vulnerable social and economic groups. We used Kenya's and Zanzibar's small-scale shark fisheries, which are illustrative of the many data-poor, small-scale shark fisheries worldwide, as case studies to explore the relationship between extinction risk and the economic and nutritional value of sharks. To achieve this, we combined existing data on shark landings, extinction risk, and nutritional value with sales data at 16 key landing sites and information from interviews with 476 fishers. Shark fisheries were an important source of economic and nutritional security, valued at >US$4 million annually and providing enough nutrition for tens of thousands of people. Economically and nutritionally, catches were dominated by threatened species (72.7% and 64.6-89.7%, respectively). The most economically valuable species were large and slow to reproduce (e.g. mobulid rays, wedgefish, and bull, silky, and mako sharks) and therefore more likely to be threatened with extinction. Given the financial incentive and intensive fishing pressure, small-scale fisheries are undoubtedly major contributors to the decline of threatened coastal shark species. In the absence of effective fisheries management and enforcement, we argue that within small-scale fisheries the conditions exist for an economically incentivized feedback loop in which vulnerable fishers are driven to persistently overfish vulnerable and declining shark species. To protect these species from extinction, this feedback loop must be broken.

Managing nutrition-biodiversity trade-offs on coral reefs

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.

A review of the global use of fishmeal and fish oil and the Fish In:Fish Out metric

Aquacultured carnivorous species consume most of the world's fishmeal and fish oil (FMFO), which itself is primarily derived from small pelagic fish. This has raised concerns about the practice's impact on wild fish stocks, ecosystems, and coastal communities that rely on these fish. The aquaculture industry claims a decreasing dependence on wild fish, relying on the Fish In:Fish Out (FIFO) metric as a ratio of the quantity of wild fish required for farmed fish production. This is misleading because it usually assumes constant FM or FO yields, inclusion rates and feed conversion ratios, which vary widely. Thus, a constant FIFO value for a given species cannot be assumed. Furthermore, low FIFO values resulting from averaging carnivores and herbivores conceal the high feed requirements of carnivore species. The increasing use of FMFO from by-products does not demonstrate a decreased use of wild fish but rather reflects a growing demand for FMFO, particularly for the fast growing and valuable salmon and shrimp farming industries.

Sustainable-use marine protected areas to improve human nutrition

Coral reef fisheries are a vital source of nutrients for thousands of nutritionally vulnerable coastal communities around the world. Marine protected areas are regions of the ocean designed to preserve or rehabilitate marine ecosystems and thereby increase reef fish biomass. Here, we evaluate the potential effects of expanding a subset of marine protected areas that allow some level of fishing within their borders (sustainable-use MPAs) to improve the nutrition of coastal communities. We estimate that, depending on site characteristics, expanding sustainable-use MPAs could increase catch by up to 20%, which could help prevent 0.3-2.85 million cases of inadequate micronutrient intake in coral reef nations. Our study highlights the potential add-on nutritional benefits of expanding sustainable-use MPAs in coral reef regions and pinpoints locations with the greatest potential to reduce inadequate micronutrient intake level. These findings provide critical knowledge given international momentum to cover 30% of the ocean with MPAs by 2030 and eradicate malnutrition in all its forms.

Commercially traded fish portfolios mask household utilization of biodiversity in wild food systems

The global biodiversity that underpins wild food systems-including fisheries-is rapidly declining. Yet, we often have only a limited understanding of how households use and benefit from biodiversity in the ecosystems surrounding them. Explicating these relationships is critical to forestall and mitigate the effects of biodiversity declines on food and nutrition security. Here, we quantify how biodiversity filters from ecosystems to household harvest, consumption, and sale, and how ecological traits and household characteristics shape these relationships. We used a unique, integrated ecological (40 sites, quarterly data collection) and household survey (n = 414, every 2 mo data collection) dataset collected over 3 y in rice field fisheries surrounding Cambodia's Tonlé Sap, one of Earth's most productive and diverse freshwater systems. While ecosystem biodiversity was positively associated with household catch, consumption, and sold biodiversity, households consumed an average of 43% of the species present in the ecosystem and sold only 9%. Larger, less nutritious, and more common species were disproportionally represented in portfolios of commercially traded species, while consumed species mirrored catches. The relationship between ecosystem and consumed biodiversity was remarkably consistent across variation in household fishing effort, demographics, and distance to nearest markets. Poorer households also consumed more species, underscoring how wild food systems may most benefit the vulnerable. Our findings amplify concerns about the impacts of biodiversity loss on our global food systems and highlight that utilization of biodiversity for consumption may far exceed what is commercially traded.

Tropical fishery nutrient production depends on biomass-based management

The need to enhance nutrient production from tropical ecosystems to feed the poor could potentially create a new framework for fisheries science and management. Early recommendations have included targeting small fishes and increasing the species richness of fish catches, which could represent a departure from more traditional approaches such as biomass-based management. To test these recommendations, we compared the outcomes of biomass-based management with hypothesized factors influencing nutrient density in nearshore artisanal fish catches in the Western Indian Ocean. We found that enhancing nutrient production depends primarily on achieving biomass-based targets. Catches dominated by low- and mid-trophic level species with smaller body sizes and faster turnover were associated with modest increases in nutrient densities, but the variability in nutrient density was small relative to human nutritional requirements. Therefore, tropical fishery management should focus on restoring biomass to achieve maximum yields and sustainability, particularly for herbivorous fishes.

Unlocking the potential of forage fish to reduce the global burden of disease

Red meat consumption is associated with an elevated risk of mortality from non-communicable diseases (NCDs). In contrast, forage fish, as highly nutritious, environmentally friendly, affordable, and the most abundant fish species in the ocean, are receiving increasing interest from a global food system perspective. However, little research has examined the impact of replacing red meat with forage fish in the global diet on diet-related NCDs.

METHODS

We based our study on datasets of red meat projections in 2050 for 137 countries and forage fish catches. We replaced the red meat consumption in each country with forage fish (from marine habitats), without exceeding the potential supply of forage fish. We used a comparative risk assessment framework to investigate how such substitutions could reduce the global burden of diet-related NCDs in adults.

RESULTS

The results of our study show that forage fish may replace only a fraction (approximately 8%) of the world's red meat due to its limited supply, but it may increase global daily per capita fish consumption close to the recommended level. Such a substitution could avoid 0.5-0.75 million deaths and 8-15 million disability-adjusted life years, concentrated in low- and middle-income countries. Forage fish as an alternative to red meat could double (or more) the number of deaths that could be avoided by simply reducing red meat consumption.

CONCLUSIONS

Our analysis suggests that forage fish is a promising alternative to red meat. Policies targeting the allocation of forage fish to regions where they are needed, such as the Global South, could be more effective in maximising the potential of forage fish to reduce the global burden of disease.

Maximizing cardiovascular benefits of fish consumption within the One Health approach: Should current recommendations be revised?

AIMS

Current dietary recommendations on fish consumption for cardiovascular disease (CVD) prevention put somewhat vague emphasis on fatty fish, mainly driven by evidence on the cardioprotective effects of n-3 PUFAs. Recent data on the consumption of different types of fish in relation to hard cardiovascular endpoints suggests that fatty but not lean fish can contribute to CVD prevention. This considered, we aimed at evaluating, by an environmental perspective, fish consumption limited to the fatty type - in appropriate amounts for optimizing CVD prevention - within the European context.

DATA SYNTHESIS

Starting from the current average intake of total fish by the European population (i.e., 2 servings/week of fatty plus lean fish), we show that the shift towards the consumption of 2 servings/week of solely fatty fish - appropriate for optimizing CVD prevention - would allow a 32% saving of greenhouse gas (GHG) emissions related to fish consumption. This is due to the lower environmental impact of fatty fish globally considered, compared to lean fish. However, since the carbon footprint of different fatty fish species can vary significantly - with small blue fish (e.g., anchovies, sardines, herrings) in the lowest range, we estimated that GHG emissions due to fish consumption in Europe could be reduced by 82% by focusing on small blue fish consumption.

CONCLUSIONS

Consumption of 2 servings/week of small blue fish could represent a feasible and effective choice among the functional dietary strategies available to achieve the maximal benefits for human and environmental health.