Publications

It is commonly agreed that marine conservation should expand considerably around the world. However, most countries have not yet implemented large-scale no-take Marine Protected Areas (MPAs). When a country closes a large fraction of its waters to fishing, it stands to lose a considerable level of fishery revenue. Although biodiversity and spillover fishing benefits may far exceed these losses, benefits from large-scale MPAs typically accrue to other countries or to the high seas. Here, to overcome this dilemma, we simulate and test an international fisheries management scheme with transferable fishing rights that incentivizes, rather than hinders, large-scale marine conservation. By combining a bioeconomic model of cross-country trading of fishing rights with vessel-level tracking data before and after a large-scale conservation action is implemented, we show that transferable fishing rights and a biomass-based allocation rule are pivotal to incentivize conservation under this market-based setting. Our work focuses on the Vessel Day Scheme (VDS)—an environmental market that is employed by the Parties to the Nauru Agreement (a group of nine Pacific Island nations) to manage their tuna fisheries—and areas in which large-scale conservation interventions have taken place. Overall, these results provide a template for how to incentivize countries to engage in large-scale marine conservation within a market-based setting.

Most bio-economic models in fisheries assume perfectly rational profit-maximizing behaviour by fishing vessels. Here we investigate this assumption empirically. Using a flexible agent-based model of fishing vessels called POSEIDON, we compared predicted fishing patterns to observed patterns in logbook data, that resulted from a wide range of stylized decision-making processes in the U.S. west coast dover sole-thornyhead-sablefish (DTS) fishery, which is managed with tradable quotas (ITQs). We found that observed vessel behaviour was best predicted in the model by simple decision algorithms whereby vessels chose between exploring new fishing grounds and revisiting previous ones based on their and other vessels’ past successes. In contrast, when the model assumed that vessels were perfect profit maximizers, the model substantially overestimated their profits and utilization of quota of rare, constraining species that carry high quota costs, such as yelloweye rockfish. Our results suggest that bounded rationality is an important driver of vessel behaviour in this fishery.

The ocean is critically important to our global economy. Collectively, it is estimated that ocean-based industries and activities contribute hundreds of millions of jobs and approximately US$2.5 trillion to the global economy each year, making it the world’s seventh-largest economy when compared with national gross domestic products (GDPs) (Hoegh-Guldberg 2015; IPCC 2019). In addition, the nonmarket services and benefits provided by the ocean are significant and may in fact far exceed the value added by market-based goods and services (Costanza et al. 2014). Anthropogenic climate change, driven by the exponential increase in emissions of greenhouse gasses (GHGs) since the industrial revolution, will continue to impact the ocean through a variety of channels. The severity of effects will depend greatly on the extent of warming reached through GHG emissions (IPCC 2018; IPCC 2019). The resulting changes to ocean processes and functioning have broad implications for our global economy that must be taken into account, both to inform adaptation efforts and motivate urgent mitigation strategies. In this paper, we focus on those sectors of the ocean economy that are most in need of adaptation to ensure they can continue to provide valued functions as the climate changes: capture fisheries, marine aquaculture, and marine and coastal tourism. We also briefly discuss other marine-based sectors, some of which generate higher monetary value at a global scale, but either face less significant existential risks from the changing climate (e.g. shipping), or must be drastically transitioned to avoid worsening the climate crisis (e.g. oil and gas extraction). However, we leave deeper discussion of these important industries and the issues surrounding them to other Blue Papers (Ocean Energy and Mineral Sources and Coastal Development).

Boundary spanning – the practice of facilitating knowledge exchange to address complex sustainability challenges – has the potential to align research and policymaking and increase the uptake of research in decision making. But the goals, methods, and outcomes of boundary-spanning activities in the environment sector can be difficult to describe, missing an opportunity to share lessons learned and improve as a community of practice. This paper describes boundary-spanning activities to integrate research about environmental sustainability with federal ocean policy dialogues in the U.S. We describe the process of organizing, facilitating, and learning from a series of meetings in which five interdisciplinary researchers engaged with federal ocean policy audiences. While the longer-term impacts of the activities associated with these meetings are subtle and remain difficult to detect, more immediate outcomes are observable. These include new professional relationships among researchers and policy staff, reported relevance of the research to general policy discourse, and a narrative that frames the opportunity for policymakers to learn from past industrialization on land as they manage an emerging industrial revolution in the ocean. By presenting the process and outcomes of our boundary-spanning activities, we aim to stimulate timely debate within ocean policy, management, and research communities about the importance of multiple benefits provided by healthy and intact ocean ecosystems and how to protect them in the face of the expanding industrialization of the ocean.

Demand for data-limited stock assessment methods is increasing, and new methods are being developed rapidly. One class of these methods requires only catch time series and, in some cases, information about life history or fishery characteristics, to estimate stock status. These catch-only methods (COMs) range from statistical models trained on data-rich stocks to mechanistic population models that make assumptions about changes in fishing effort. We review 11 COMs, comparing performance through application to data-rich stocks and simulated fisheries. The catch-only methods evaluated here produce imprecise and biased estimates of B/B_MSY, especially for stocks that are lightly exploited. They were also generally poor classifiers of stock status. While no method performed best across all stocks, ensembles of multiple COMs generally performed better than individual COMs. We advocate for testing new COMs using this common platform. We also caution that performance in estimating stock status is not sufficient for gauging the usefulness of COMs in managing fisheries. Greater use of management strategy evaluation is needed before COMs can be considered a reliable tool for management.

Global food demand is rising, and serious questions remain about whether supply can increase sustainably¹. Land-based expansion is possible but may exacerbate climate change and biodiversity loss, and compromise the delivery of other ecosystem services^2,3,4,5,6. As food from the sea represents only 17% of the current production of edible meat, we ask how much food we can expect the ocean to sustainably produce by 2050. Here we examine the main food-producing sectors in the ocean—wild fisheries, finfish mariculture and bivalve mariculture—to estimate ‘sustainable supply curves’ that account for ecological, economic, regulatory and technological constraints. We overlay these supply curves with demand scenarios to estimate future seafood production. We find that under our estimated demand shifts and supply scenarios (which account for policy reform and technology improvements), edible food from the sea could increase by 21–44 million tonnes by 2050, a 36–74% increase compared to current yields. This represents 12–25% of the estimated increase in all meat needed to feed 9.8 billion people by 2050. Increases in all three sectors are likely, but are most pronounced for mariculture. Whether these production potentials are realized sustainably will depend on factors such as policy reforms, technological innovation and the extent of future shifts in demand.

Territorial use rights in fisheries (TURFs) are coastal territories assigned to fishermen for the exclusive extraction of marine resources. Recent evidence shows that the incentives that arise from these systems can improve fisheries sustainability. Although research on TURFs has increased in recent years, important questions regarding the social and ecological dynamics underlying their success remain largely unanswered. In particular, in order to create new successful TURFs, it is critical to comprehend how fish movement over different distances affects the development of sustainable fishing practices within a TURF. In theory, excessive spillover outside a TURF will generate incentives to overharvest. However, many TURFs have proven successful even when targeted species move over distances far greater than the TURF's size. A common attribute among some of these successful systems is the presence of inter-TURF cooperation arrangements. This raises the question of how different levels and types of cooperation affect the motivations for overharvesting driven by the movement of fish outside the TURF. In this paper, we examine equilibrium yields under different levels of inter-TURF cooperation (from partial to full) and varying degrees of asymmetry across TURFs of both biological capacity and benefit-sharing. We find that partial cooperation can improve yields even with an unequal distribution of shared benefits and asymmetric carrying capacity. However, cooperation arrangements are unstable if the sharing agreement and biological asymmetries are misaligned. Remarkably, we find that asymmetry in the system can lead to the creation of voluntary no-take zones.

We compile global data to examine the current status, trends, threats, and opportunities in the world’s wild-capture fisheries.We find that global fisheries have largely diverged—well-managed, often industrial fisheries tend to be in reasonably good health, while coastal fisheries, often from low-governance regions, tend to be in poor health. Good governance seems to play a central role, and we summarize key findings from the literature on how effective fishery management can simultaneously increase food security, livelihoods, and conservation outcomes. Other solutions, such as marine protected areas and big data, can be useful but will not, by themselves, solve the main fishery challenges.We conclude by examining notorious threats, such as climate change and lack of governance on the high seas, and find that these can be largely neutralized with good fishery management, suggesting that overall, the future of wild fisheries can be bright with effective fishery management interventions.

Climate change is driving shifts in the abundance and distribution of marine fish and invertebrates and is having direct and indirect impacts on seafood catches and fishing communities, exacerbating the already negative effects of unsustainably high fishing pressure that exist for some stocks. Although the majority of fisheries in the world are managed at the national or local scale, most existing approaches to assessing climate impacts on fisheries have been developed on a global scale. It is often difficult to translate from the global to regional and local settings because of limited relevant data. To address the need for fisheries management entities to identify those fisheries with the greatest potential for climate change impacts, we present an approach for estimating expected climate change-driven impacts on the productivity and spatial range of fisheries at the regional scale in a data-poor context. We use a set of representative Mexican fisheries as test cases. To assess the implications of climate impacts, we compare biomass, harvest, and profit outcomes from a bioeconomic model under contrasting management policies and with and without climate change. Overall results show that climate change is estimated to negatively affect nearly every fishery in our study. However, the results indicate that overfishing is a greater threat than climate change for these fisheries, hence fixing current management challenges has a greater upside than the projected future costs of moderate levels of climate change. Additionally, this study provides meaningful first approximations of potential effects of both climate change and management reform in Mexican fisheries. Using the climate impact estimations and model outputs, we identify high priority stocks, fleets, and regions for policy reform in Mexico in the face of climate change. This approach can be applied in other data-poor circumstances to focus future research and policy reform efforts on stocks now subject to additional stress due to climate change. Considering their growing relevance as a critical source of protein and micronutrients to nourish our growing population, it is urgent for regions to develop sound fishery management policies in the short-term as they are the most important intervention to mitigate the adverse effects of climate change on marine fisheries.

Environmental markets are widely prescribed as an alternative to open-access regimes for natural resources. We develop a model of dynamic groundwater extraction to demonstrate how a spatial regression discontinuity design that exploits a spatially-incomplete market for groundwater rights recovers a lower bound on the market’s net benefit. We apply this estimator to a major aquifer in water-scarce southern California and find that a groundwater market generated substantial net benefits, as capitalized in land values. Heterogeneity analyses point to gains arising in part from rights trading, enabling more efficient water use across sectors. Additional findings suggest the market increased groundwater levels.

Twenty years ago, the creation of a new scientific program, the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO), funded by the Packard Foundation, provided the opportunity to integrate—from the outset—research, monitoring, and outreach to the public, policymakers, and managers. PISCO’s outreach efforts were initially focused primarily on sharing scientific findings with lay audiences, but over time they evolved to a more interactive, multi-directional mode of engagement. Over the next two decades, PISCO science and scientists significantly influenced local, state, federal, and international decisions about many topics, but especially marine protected areas, hypoxia, ocean acidification, fishery management, and marine diseases. PISCO scientists’ long-term data and understanding of key ecosystem processes also enabled them to detect anomalies, investigate rapidly, and inform others about novel developments such as hypoxia, acidification, warming, and disease. Especially during a time of dynamic changes in ecosystems, long-term data like PISCO’s have proven invaluable. Moreover, PISCO’s dual focus on understanding fundamental processes and finding solutions (not just identifying problems) has resulted in rich opportunities to co-create knowledge with citizens and translate that knowledge into action by citizens, managers, and policymakers. PISCO has delivered on its goal to serve society through science.

Coastal marine ecosystems provide livelihoods for small-scale fishers and coastal communities around the world. Small-scale fisheries face great challenges since they are difficult to monitor, enforce, and manage, which may lead to overexploitation. Combining territorial use rights for fisheries (TURF) with no-take marine reserves to create TURF-reserves can improve the performance of small-scale fisheries by buffering fisheries from environmental variability and management errors, while ensuring that fishers reap the benefits of conservation investments. Since 2012, 18 old and new community-based Mexican TURF-reserves gained legal recognition thanks to a regulation passed in 2012; their effectiveness has not been formally evaluated. We combine causal inference techniques and the Social-Ecological Systems framework to provide a holistic evaluation of community-based TURF-reserves in three coastal communities in Mexico. We find that, overall, reserves have not yet achieved their stated goals of increasing the density of lobster and other benthic invertebrates, nor increasing lobster catches. A lack of clear ecological and socioeconomic effects likely results from a combination of factors. First, some of these reserves might be too young for the effects to show (reserves were 6–10 years old). Second, the reserves are not large enough to protect mobile species, like lobster. Third, variable and extreme oceanographic conditions have impacted harvested populations. Fourth, local fisheries are already well managed, and while reserves may protect populations within its boundaries, it is unlikely that reserves might have a detectable effect in catches. However, even small reserves are expected to provide benefits for sedentary invertebrates over longer time frames, with continued protection. These reserves may provide a foundation for establishing additional, larger marine reserves needed to effectively conserve mobile species.

Growing evidence suggests that drought risk is increasing due to climate change. Evaluation of potential policy responses involves understanding complex economic tradeoffs, hydrologic and social feedbacks, and recognizing how combinations of interventions may have complementary or conflicting effects. This paper explores the potential that coupled human–natural system models have to address these questions. We employ a detailed model of the Willamette River Basin, Oregon, to evaluate the effectiveness of a variety of potential drought policy interventions to conserve or reallocate water during a simulated near-term drought year. The drought year is characterized by early-season low flows that make it impossible to meet water demands. The results indicate that while the policies are effective at conserving water, they have limited ability to mitigate the shortages because the timing and location of conservation responses do not match the timing and location of the shortages.

Marine protected areas (MPAs) are important tools for managing marine ecosystems. MPAs are expected to replenish nearby exploited populations through the natural dispersal of young, but the models that make these predictions rely on assumptions that have recently been demonstrated to be incorrect for most species of fish. A meta-analysis showed that fish reproductive output scales “hyperallometrically” with fish mass, such that larger fish produce more offspring per unit body mass than smaller fish. Because fish are often larger inside MPAs, they should exhibit disproportionately higher reproductive output as compared to fish outside of MPAs. We explore the consequences of hyperallometric reproduction for a range of species for population replenishment and the productivity of exploited species. We show that the reproductive contribution of fish inside MPAs has been systematically underestimated and that fisheries yields can be enhanced by the establishment of reservoirs of larger, highly fecund fish.

Despite overall global growth of marine and coastal aquaculture (i.e., mariculture), there is substantial regional heterogeneity in production. Biophysical growing conditions do not explain variation in production, indicating that other economic, social, and political drivers are likely influencing geographic patterns of industry development. The Caribbean is one such region where mariculture has considerable potential, but current production is very low. This is particularly surprising because the region relies heavily on seafood products and has experienced substantial declines in capture fisheries. Given the discrepancy between potential and realized production, this paper evaluates governance mechanisms (e.g., policies, laws, and regulations) related to current and future mariculture production in the Caribbean. We review literature examining the development and governance of several emerging industries, which we use to inform a Mariculture Governance Index that we assess for each Caribbean country and interpret relative to their current and potential mariculture production. Further, we seek to provide insight into the dynamic relationship between governance and mariculture development through country-specific case studies by exploring the timelines of mariculture growth relative to the timing of mariculture policy and legislation for select countries. This work develops a method for better understanding the role of governance in mariculture development and is applicable across regions, providing valuable context for identifying opportunities and barriers to mariculture expansion.

Economic losses from natural disasters have been increasing in recent decades. This has been attributed mainly to population and economic growth in disaster-prone areas. Future natural disaster losses are expected to increase due to a continued increase in economic exposure and climate change. This highlights the importance of designing policies that can mitigate the impacts of these disasters on the economy and society. A rapidly expanding literature has estimated the direct (e.g., property damage) and indirect (e.g., gross domestic product growth, trade) economic impacts of natural disasters. This article reviews this emerging literature. We synthesize the main theoretical, computational, and empirical methods used, summarize key findings on the economic impacts of natural disasters, and discuss factors that have been found to mitigate disaster impacts. We conclude by identifying lessons for policymakers and outlining an agenda for future research in this field.

Narratives help frame our thinking and action. On the eve of World Oceans Day and in anticipation of the United Nations Decade of Ocean Science for Sustainable Development (2021–2030), a new narrative for the ocean is warranted—one that reflects current scientific knowledge and inspires new science and effective action.

For most of human history, people considered the ocean so immense, bountiful, and resilient that it was impossible to deplete or disrupt it. The overarching narrative was, “The ocean is so vast, it is simply too big to fail.” This mindset persists today, bringing even more intense, unsustainable uses of the ocean that reflect ignorance; the allure of new economic opportunity; or the need for food, resources, and development. However, the folly of this too-big-to-fail narrative has become glaringly obvious through overpowering scientific evidence of depletion, disruption, and pollution. Climate change, ocean acidification, habitat destruction, overfishing, and nutrient, plastic, and toxic pollution are insidious. These changes threaten the most vulnerable people; the economic prosperity, quality of life, and opportunities for everyone; and the well-being of the ocean's amazing life forms. Problems appear too complex, vested interests too powerful, and system inertia too great, especially as demands on the ocean escalate. A new narrative has arisen: “The ocean is massively and fatally depleted and disrupted. The ocean is simply too big to fix.” The result? Depression and lack of engagement and motivation.

The growth of marine aquaculture over the 21st century is a promising venture for food security because of its potential to fulfill the seafood deficit in the future. However, to maximize the use of marine space and its resources, the spatial planning of marine aquaculture needs to consider the regimes of climate variability in the oceanic environment, which are characterized by large-amplitude interannual to decadal fluctuations. It is common to see aquaculture spatial planning schemes that do not take variability into consideration. This assumption may be critical for management and for the expansion of marine aquaculture, because projects require investments of capital and need to be profitable to establish and thrive. We analyze the effect of climate variability on the profitability of hypothetical mussel aquaculture systems in the Southern California Bight. Using historical environmental data from 1981 to 2008, we combine mussel production and economics models at different sites along the coast to estimate the Net Present Value as an economic indicator of profitability. We find that productivity of the farms exhibits a strong coherent behavior with marketed decadal fluctuations that are connected to climate of the North Pacific Basin, in particular linked to the phases of the North Pacific Gyre Oscillation (NPGO). This decadal variability has a strong impact on profitability both temporally and spatially, and emerges because of the mussels’ dependence on multiple oceanic environmental variables. Depending on the trend of the decadal regimes in mussel productivity and the location of the farms, these climate fluctuations will affect cost recovery horizon and profitability for a given farm. These results suggest that climate variability should be taken into consideration by managers and investors on decision making to maximize profitability.

Food security remains a principal challenge in the developing tropics where communities rely heavily on marine-based protein. While some improvements in fisheries management have been made in these regions, a large fraction of coastal fisheries remain unmanaged, mismanaged, or use only crude input controls. These quasi-open-access conditions often lead to severe overfishing, depleted stocks, and compromised food security. A possible fishery management approach in these institution-poor settings is to implement fully protected marine protected areas (MPAs). Although the primary push for MPAs has been to solve the conservation problems that arise from mismanagement, MPAs can also benefit fisheries beyond their borders. The literature has not completely characterized how to design MPAs under diverse ecological and economic conditions when food security is the objective. We integrated four key biological and economic variables (i.e., fish population growth rate, fish mobility, fish price, and fishing cost) as well as an important aspect of reserve design (MPA size) into a general model and determined their combined influence on food security when MPAs are implemented in an open-access setting. We explicitly modeled open-access conditions that account for the behavioral response of fishers to the MPA; this approach is distinct from much of the literature that focuses on assumptions of “scorched earth” (i.e., severe over-fishing), optimized management, or an arbitrarily defined fishing mortality outside the MPA’s boundaries. We found that the MPA size that optimizes catch depends strongly on economic variables. Large MPAs optimize catch for species heavily harvested for their high value and/or low harvesting cost, while small MPAs or no closure are best for species lightly harvested for their low value and high harvesting cost. Contrary to previous theoretical expectations, both high and low mobility species are expected to experience conservation benefits from protection, although, as shown previously, greater conservation benefits are expected for low mobility species. Food security benefits from MPAs can be obtained from species of any mobility. Results deliver both qualitative insights and quantitative guidance for designing MPAs for food security in open-access fisheries.

Domestic political processes shape climate policy. In particular, there is increasing concern about the role of political lobbying over climate policy. This paper examines how lobbying spending on the Waxman–Markey bill, the most prominent and promising United States climate regulation so far, altered its likelihood of being implemented. We combine data from comprehensive United States lobbying records with an empirical method for forecasting the policy’s effect on the value of publicly listed firms. Our statistical analysis suggests that lobbying by firms expecting losses from the policy was more effective than lobbying by firms expecting gains. Interpreting this finding through a game-theoretic model, we calculate that lobbying lowered the probability of enacting the Waxman–Markey bill by 13 percentage points, representing an expected social cost of US$60 billion (in 2018 US dollars). Our findings also suggest how future climate policy proposals can be designed to be more robust to political opposition.