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Aquaculture policy often promotes production of low-trophic level species for sustainable industry growth. Yet, the application of the trophic level concept to aquaculture is complex, and its value for assessing sustainability is further complicated by continual reformulation of feeds. The majority of fed farmed fish and invertebrate species are produced using human-made compound feeds that can differ markedly from the diet of the same species in the wild and continue to change in composition. Using data on aquaculture feeds, we show that technical advances have substantially decreased the mean effective trophic level of farmed species, such as salmon (mean TL = 3.48 to 2.42) and tilapia (2.32 to 2.06), from 1995 to 2015. As farmed species diverge in effective trophic level from their wild counterparts, they are coalescing at a similar effective trophic level due to standardisation of feeds. This pattern blurs the interpretation of trophic level in aquaculture because it can no longer be viewed as a trait of the farmed species, but rather is a dynamic feature of the production system. Guidance based on wild trophic position or historical resource use is therefore misleading. Effective aquaculture policy needs to avoid overly simplistic sustainability indicators such as trophic level. Instead, employing empirically derived metrics based on the specific farmed properties of species groups, management techniques and advances in feed formulation will be crucial for achieving truly sustainable options for farmed seafood.

Feeding a growing, increasingly affluent population while limiting environmental pressures of food production is a central challenge for society. Understanding the location and magnitude of food production is key to addressing this challenge because pressures vary substantially across food production types. Applying data and models from life cycle assessment with the methodologies for mapping cumulative environmental impacts of human activities (hereafter cumulative impact mapping) provides a powerful approach to spatially map the cumulative environmental pressure of food production in a way that is consistent and comprehensive across food types. However, these methodologies have yet to be combined. By synthesizing life cycle assessment and cumulative impact mapping methodologies, we provide guidance for comprehensively and cumulatively mapping the environmental pressures (e.g., greenhouse gas emissions, spatial occupancy, and freshwater use) associated with food production systems. This spatial approach enables quantification of current and potential future environmental pressures, which is needed for decision makers to create more sustainable food policies and practices. ª 2020 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

With the global supply of forage fish at a plateau, fed aquaculture must continue to reduce dependence on fishmeal and oil in feeds to ensure sustainable sector growth. The use of novel aquaculture feed ingredients is growing, but their contributions to scalable and sustainable aquafeed solutions are unclear. Here, we show that global adoption of novel aquafeeds could substantially reduce aquaculture’s forage fish demand by 2030, maintaining feed efficiencies and omega-3 fatty acid profiles. We combine production data, scenario modelling and a decade of experimental data on forage fish replacement using microalgae, macroalgae, bacteria, yeast and insects to illustrate how reducing future fish oil demand, particularly in high-value species such as salmonids, will be key for the sustainability of fed aquaculture. However, considerable uncertainties remain surrounding novel feed efficacy across different life-cycle stages and taxa, and various social, environmental, economic and regulatory challenges will dictate their widespread use. Yet, we demonstrate how even limited adoption of novel feeds could aid sustainable aquaculture growth, which will become increasingly important for food security.

Seaweed farming is widely expected to transform the way we approach sustainable developments, particularly in the context of the ‘Blue Economy’. However, many claims of the social and ecological benefits from seaweed farming have limited or contextually weak empirical grounding. Here we systematically review relevant publications across four languages to form a comprehensive picture of observed—rather than theorised—social and environmental impacts of seaweed farming globally. We show that, while some impacts such as improved water quality and coastal livelihoods are consistently reported, other promulgated benefits vary across cultivation contexts or are empirically unsubstantiated. For some communities, increasing dependence on seaweed farming may improve or worsen the cultural fabric and their vulnerability to economic and environmental shocks. The empirical evidence for the impacts of seaweed farming is also restricted geographically, mainly to East Asia and South-East Asia, and taxonomically. Seaweed farming holds strong potential to contribute to sustainability objectives, but the social and ecological risks associated with scaling up global production remain only superficially understood. These risks require greater attention to ensure just, equitable, and sustainable seaweed industries can be realised.

Coastal regions are essential to achieving the Sustainable Development Goals (SDGs) given their importance for human habitation, resource provisioning, employment, and cultural practice. They are also regions where different ecological, disciplinary, and jurisdictional boundaries both overlap and are obscured. We thus propose the land-sea interface as areas where governance systems are most in need of frameworks for systems analysis to meet the SDGs—which are inherently interconnected— and integrate complex interdependencies between human livelihoods, energy, transport, food production, and nutrient flows (among others). We propose a strategic land-sea governance framework built on the sustainable transitions literature to plan for governance to achieve sustainable development across the land-sea interface. To illustrate our proposal, we compare governance planning processes across four case-based scenarios: an industrialized coastal country, a least developed coastal country, a developing coastal country with local dependencies on ocean resources, and a small island developing state primarily dependent on tourism. Through the lens of aligning governance actors and actions vertically (subnational to national), horizontally (across sectors), and programmatically (from goals to implementation), we propose scales at which governance systems may be misaligned, such as where different agencies that affect marine systems have conflicting visions and goals, leading to stalled progress or counterproductive actions. Where possible, we also highlight strategies to align across scales of high level strategic policy, tactical scale institutional mandates and cooperation, and on the ground activities and operations, such as aligning actors based on an analysis of interdependencies of goals.

Improving global food systems is essential to addressing climate change, mitigating biodiversity loss, and meeting both sustainability and human development goals. International assessments from the Intergovernmental Panel on Climate Change and Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services and business and technology innovations such as lab-grown and plant-based meat, as well as many consumer diet trends, can all be traced to studies that identify undesirable impacts of certain food systems. Yet the evidence underpinning many widely touted recommendations about what to grow and eat is remarkably sparse and generally biased. The web of food impacts and interactions is challenging to map, let alone fully assess. We must address the holes in food assessment studies and the paucity of linkages among foods in these assessments to fully understand the cumulative impact of food production. Image credit: Shutterstock/Olga Klochanko. We know that not all food is created equal in terms of environmental impact (1⇓–3). However, most past research has focused on only a few key foods (e.g., beef and staple crops) and only a few environmental stressors (particularly greenhouse gas emissions). In addition, these studies tend to be confined to a few countries, and many nations suffer from poor knowledge transfer between the scientific community and the public. Even the most wide-ranging assessments made to date (2, 4, 5) contain significant gaps (Fig. 1). These biases arise, first, because substantial portions of the global food system are inaccurately or insufficiently reported or effectively “hidden” from standard statistics (e.g., inland and small-scale fisheries, bushmeat, backyard farming) and, second, because of an incomplete knowledge of the suite of environmental impacts and how these propagate through the many linkages among food systems. Fig. 1. Comparative food impact studies published in the last 10 years are skewed in favor of a handful … [↵][1]1To whom correspondence may be addressed. Email: halpern{at}nceas.ucsb.edu. [1]: #xref-corresp-1-1

The United States seafood industry is undergoing rapid change, as a result of the current trade war with China, ongoing global COVID-19 pandemic, and new governance mandates. The Executive Order on Promoting American Seafood Competitiveness and Economic Growth , signed in May 2020, proposes wild-capture fisheries deregulation and prioritization of aquaculture, with an emphasis on offshore development. Recent disruption of wild-caught seafood supply and demand could create space for sustainable aquaculture growth, but expansion could also undermine wild fisheries livelihoods and economics if integrated management between industries is ignored. Here, we review the current state of US seafood and outline five guiding principles around the implementation, and possible modifications, of the Executive Order to facilitate sustainable US fisheries and aquaculture: (1) make precise and strategic fisheries reforms that continue to support sustainable wild fisheries, (2) integrate aquaculture and fisheries using an ecosystem-based approach, (3) improve aquaculture data collection, (4) address social resistance to aquaculture, and (5) reconcile nationalism in a global market. Regardless of the Head of State, implementation of these science-informed principles is critical for balancing social-ecological tradeoffs between wild captured and farmed seafood systems, and for ensuring a more resilient US seafood sector under an anticipated future of increased volatility.

The COVID-19 pandemic and subsequent lockdowns are creating health and economic crises that threaten food and nutrition security. The seafood sector provides important sources of employment and nutrition, especially in low-income countries, and is highly globalized, allowing shocks to propagate internationally. We use a resilience ‘action cycle’ framework to study the first five months of COVID-19-related disruptions, impacts, and responses to the seafood sector. Looking across high- and low-income countries, we find that some supply chains, market segments, companies, small-scale actors and civil society have shown initial signs of greater resilience than others. For example, frozen Ecuadorian shrimp and Chinese tilapia exports were diverted to alternative markets, while live-fresh supply chains were more impacted. COVID-19 has also highlighted the vulnerability of certain groups working in- or dependent on the seafood sector. We discuss early coping and adaptive responses, combined with lessons from past shocks, that could be considered when building resilience in the sector.

The United States seafood sector is susceptible to shocks, both because of the seasonal nature of many of its domestic fisheries and its global position as a top importer and exporter of seafood. However, many datasets that could inform science and policy during an emerging event do not exist or are only released months or years later. Here we synthesize multiple data sources from across the seafood supply chain, including unconventional real-time datasets, to show the relative initial responses and indicators of recovery during the COVID-19 pandemic. We synthesized news articles from January to September, 2020 that reported effects of COVID-19 on the US seafood sector, including processor closures, shortened fishing seasons, and loss of revenue. Concerning production and distribution, we assessed past and present landings and trade data and found substantial declines in fresh seafood catches (-40%), imports (-37%) and exports (-43%) relative to the previous year, while frozen seafood products were generally less affected. Google search trends and seafood market foot traffic data suggest consumer demand for seafood from restaurants dropped by upwards of 70% during lockdowns, with recovery varying by state. However, these declines were partially offset by an increase (270%) in delivery and take-out service searches. Our synthesis of open-access datasets and media reports shows widespread, but heterogeneous, ramifications of COVID-19 across the seafood sector, implying that policy-makers should focus support on states and sub-sectors most affected by the pandemic: fishery-dependent communities, processors, and fisheries and aquaculture that focus on fresh products.

The adoption of sustainable alternative foods could potentially reduce the environmental burden of human food production if it can reduce demand for products with higher environmental impact. However, there is little empirical evidence for how frequent food consumption declines are when alternative foods are introduced, limiting our knowledge of the potential for such introductions to drive food system transformations. Using 53 years of food supply data for 99 crop, livestock, and seafood commodities in 159 countries, we use regression analyses on 12 883 time series—each representing a single country-commodity pair—to detect sustained declines in apparent national food consumption, as well as corresponding consumption increases of other food commodities. First, we show that sustained declines in the consumption of any food item are rare, occurring in 9.6% of time series. Where declines are present, they most frequently occur in traditional plant-based staples, e.g. starchy roots, and are larger compared to animal-source foods, particularly in low- and middle-income countries where much of the future increase in food demand is expected to occur. Second, although declines were rare, we found national production rather than trade was identified as the most common proximate driver of declines in consumption, suggesting that shifts in diets have the potential to translate into reduced environmental impacts from food production. Third, we found consumption increases were nearly twice as common as declines, but only 8% of declines (from within 4% of total time series) occurred parallel to incline events within the same food group, suggesting limited interchangeability. An examination of case studies suggests that alternative foods can facilitate food system transitions, but strong relative disadvantages for existing foods across aspects of technology, markets, policy and culture need to exist in parallel to support for alternative foods across the same factors. Where existing foods are already produced in highly efficient systems, a lack of systematic disadvantage may provide a barrier to alternative foods driving change.

With human food production a major driver of global environmental change, there is increasing recognition of the importance of shifting towards more sustainable dietary patterns. With wholesale dietary change notoriously difficult to implement at scale, various new food analogues have emerged to serve as qualitatively similar (e.g., taste, texture) but lower environmental impact alternatives for existing foods, particularly animal protein. While new foods may have low environmental impacts, very little is known about how reliably new products drive the disadoption (permanently reduced or ceased consumption) of existing foods. Using simple models of the interplay between adoption levels, substitution ratios of new and existing foods, and different products targeted for replacement, we explore the role of food disadoption on the global warming potential of protein consumption by a theoretical human population. We show how counterintuitive changes to the total environmental impacts attributable to food consumption are plausible following widespread uptake of "sustainable" new foods if they do not reliably drive the disadoption of existing high-impact alternatives. Greater empirical evidence of how effectively new foods drive the disadoption of their intended targets is needed to prevent mass development of alternatives that exacerbate the environmental impact of human diets.

With the human population expected to near 10 billion by 2050, and diets shifting towards greater per-capita consumption of animal protein, meeting future food demands will place ever-growing burdens on natural resources and those dependent on them. Solutions proposed to increase the sustainability of agriculture, aquaculture, and capture fisheries have typically approached development from single sector perspectives. Recent work highlights the importance of recognising links among food sectors, and the challenge cross-sector dependencies create for sustainable food production. Yet without understanding the full suite of interactions between food systems on land and sea, development in one sector may result in unanticipated trade-offs in another. We review the interactions between terrestrial and aquatic food systems. We show that most of the studied land-sea interactions fall into at least one of four categories: ecosystem connectivity, feed interdependencies, livelihood interactions, and climate feedback. Critically, these interactions modify nutrient flows, and the partitioning of natural resource use between land and sea, amid a backdrop of climate variability and change that reaches across all sectors. Addressing counter-productive trade-offs resulting from land-sea links will require simultaneous improvements in food production and consumption efficiency, while creating more sustainable feed products for fish and livestock. Food security research and policy also needs to better integrate aquatic and terrestrial production to anticipate how cross-sector interactions could transmit change across ecosystem and governance boundaries into the future.

International audience; Fisheries and aquaculture make a crucial contribution to global food security, nutrition and livelihoods. However, the UN Sustainable Development Goals separate marine and terrestrial food production sectors and ecosystems. To sustainably meet increasing global demands for fish, the interlinkages among goals within and across fisheries, aquaculture and agriculture sectors must be recognized and addressed along with their changing nature. Here, we assess and highlight development challenges for fisheries-dependent countries based on analyses of interactions and trade-offs between goals focusing on food, biodiversity and climate change. We demonstrate that some countries are likely to face double jeopardies in both fisheries and agriculture sectors under climate change. The strategies to mitigate these risks will be context-dependent, and will need to directly address the trade-offs among Sustainable Development Goals, such as halting biodiversity loss and reducing poverty. Countries with low adaptive capacity but increasing demand for food require greater support and capacity building to transition towards reconciling trade-offs. Necessary actions are context-dependent and include effective governance, improved management and conservation, maximizing societal and environmental benefits from trade, increased equitability of distribution and innovation in food production, including continued development of low input and low impact aquaculture.

This study employs a uniquely multi-factorial, large-scale design to investigate baseline differences and the effects of a singular outdoor educational program on environmental attitudes, knowledge...

Climate change is impacting marine ecosystems and their goods and services in diverse ways, which can directly hinder our ability to achieve the Sustainable Development Goals (SDGs), set out under the 2030 Agenda for Sustainable Development. Through expert elicitation and a literature review, we find that most climate change effects have a wide variety of negative consequences across marine ecosystem services, though most studies have highlighted impacts from warming and consequences of marine species. Climate change is expected to negatively influence marine ecosystem services through global stressors—such as ocean warming and acidification—but also by amplifying local and regional stressors such as freshwater runoff and pollution load. Experts indicated that all SDGs would be overwhelmingly negatively affected by these climate impacts on marine ecosystem services, with eliminating hunger being among the most directly negatively affected SDG. Despite these challenges, the SDGs aiming to transform our consumption and production practices and develop clean energy systems are found to be least affected by marine climate impacts. These findings represent a strategic point of entry for countries to achieve sustainable development, given that these two goals are relatively robust to climate impacts and that they are important pre‐requisite for other SDGs. Our results suggest that climate change impacts on marine ecosystems are set to make the SDGs a moving target travelling away from us. Effective and urgent action towards sustainable development, including mitigating and adapting to climate impacts on marine systems are important to achieve the SDGs, but the longer this action stalls the more distant these goals will become.

Correction to Supporting Information for “Opinion: Putting all foods on the same table: Achieving sustainable food systems requires full accounting,” by Benjamin S. Halpern, Richard S. Cottrell, Julia L. Blanchard, Lex Bouwman, Halley E. Froehlich, Jessica A. Gephart, Nis Sand Jacobsen, Caitlin D. Kuempel, Peter B. McIntyre, Marc Metian, Daniel D. Moran, Kirsty L. Nash, Johannes Tobben, and David R. Williams, which was first published September 10, 2019; 10.1073/pnas.1913308116 (Proc. Natl. Acad. Sci. U.S.A. 116, 18152–18156). The authors note that the following datasets were missing from the published article: Dataset S1, Dataset S2, and Dataset S3. The datasets have been added online.

Climate change, in combination with population growth, is placing increasing pressure on the world’s oceans and their resources. This is threatening sustainability and societal wellbeing. Responding to these complex and synergistic challenges requires holistic management arrangements. To this end, ecosystem-based management (EBM) promises much by recognising the need to manage the ecosystem in its entirety, including the human dimensions. However, operationalisation of EBM in the marine environment has been slow. One reason may be a lack of the inter-disciplinary science required to address complex social–ecological marine systems. In the present paper, we synthesise the collective experience of the authors to explore progress in integrating natural and social sciences in marine EBM research, illustrating actual and potential contributions. We identify informal barriers to and incentives for this type of research. We find that the integration of natural and social science has progressed at most stages of the marine EBM cycle; however, practitioners do not yet have the capacity to address all of the problems that have led to the call for inter-disciplinary research. In addition, we assess how we can support the next generation of researchers to undertake the effective inter-disciplinary research required to assist with operationalising marine EBM, particularly in a changing climate.