Publications

Natural resources are often subject to state uncertainty: resource abundance is not known with certainty, but can be measured. Measurements are typically imperfect and costly to obtain. The decision of whether to invest in resource measurement may be influenced by other state variables, for example a resource commodity price. We introduce a mixed-observability model of optimal forest management featuring a partially-observable forest resource and perfectly-observable stochastic price. The decision maker optimizes the expected net present value of forest returns by choosing when to measure current forest volume (conduct an inventory), harvest and replant, or delay action. Parameter values are obtained from numerous forestry data sources. Optimal investment in inventory reduces the cost of uncertainty about timber volume and increases the predictability of returns. Moreover, price stochasticity interacts with inventory decisions to produce asymmetric effects of high and low prices on inventory timing. We also produce the first graphical Faustmann rule analogues for jointly-optimal inventory and harvest.

Technology adoption often requires multiple stages of investment. As new information emerges, agents may abandon a technology that was profitable in expectation. We use a field experiment to vary the payoffs at two stages of investment in a new technology: a tree species that provides on-farm fertilizer benefits. Farmer decisions identify the information about profitability that arrives between the take-up and follow-through stages. Results show that this form of uncertainty increases take-up but lowers average tree survival, decreasing the cost-effectiveness of take-up subsidies. Thus, uncertainty offers another explanation for why even costly technologies may go unused or be abandoned.

In California, record-breaking fires in 2017 and 2018 destroyed communities and dominated headlines across the country. The Thomas fire in Ventura and Santa Barbara Counties, and the Tubbs fire in Napa, Sonoma, and Lake Counties damaged or destroyed over 7,200 structures, burning over 318,000 acres in
2017. In 2018, the Woolsey fire in Los Angeles and Ventura Counties damaged 1,990 structures, burning almost 97,000 acres. The Camp fire in Paradise damaged 19,531 structures, becoming the most destructive fire in California history. In this report, we put these recent events into broader historical perspective, using a newly developed dataset that catalogues wildfire damages dating back to 1979. This report presents this novel data set, which illustrates that these recent severe fires are part of a broader trend of increasing fire burn area and damages over the last 40 years.

One of the aims of the United Nations (UN) negotiations on the conservation and sustainable use of marine biodiversity in areas beyond national jurisdiction (ABNJ) is to develop a legal process for the establishment of area-based management tools, including marine protected areas, in ABNJ. Here we use a conservation planning algorithm to integrate 55 global data layers on ABNJ species diversity, habitat heterogeneity, benthic features, productivity, and fishing as a means for highlighting priority regions in ABNJ to be considered for spatial protection. We also include information on forecasted species distributions under climate change. We found that parameterizing the planning algorithm to protect at least 30% of these key ABNJ conservation features, while avoiding areas of high fishing effort, yielded a solution that highlights 52,545,634 km² (23.7%) of ABNJ as high priority regions for protection. Instructing the planning model to avoid ABNJ areas with high fishing effort resulted in relatively minor shifts in the planning solution, when compared to a separate model that did not consider fishing effort. Integrating information on climate change had a similarly minor influence on the planning solution, suggesting that climate-informed ABNJ protected areas may be able to protect biodiversity now and in the future. This globally standardized, data-driven process for identifying priority ABNJ regions for protection serves as a valuable complement to other expert-driven processes underway to highlight ecologically or biologically significant ABNJ regions. Both the outputs and methods exhibited in this analysis can additively inform UN decision-making concerning establishment of ABNJ protected areas.

As human use of the oceans increases, marine spatial planning (MSP) is being more widely adopted to achieve improved environmental, economic, and social outcomes. However, there is a lack of practical guidance for stakeholder driven, scientifically informed MSP processes in small island and data-limited contexts. Here, we present an overview of MSP on the Caribbean island of Montserrat, with a focus on the scientific and technical input that helped inform the process. Montserrat presents an interesting case study of MSP in the small island context as it has ocean uses that are common to many islands, namely small-scale fisheries and tourism, but the marine environment has been heavily impacted due to volcanic activity. We detail the methods for data collection and analysis and the decision-making process that contributed to a marine spatial plan. We highlight aspects of the process that may be useful for other small islands embarking on MSP, and lessons learned regarding scientific support, including the need for on-site scientific support and guidance throughout MSP, the importance of setting clear objectives, working within data limitations and making data accessible, and choosing and using appropriate decision support tools.

Although climate change is altering the productivity and distribution of marine fisheries, climate-adaptive fisheries management could mitigate many of the negative impacts on human society. We forecast global fisheries biomass, catch, and profits to 2100 under three climate scenarios (RCPs 4.5, 6.0, 8.5) and five levels of management reform to (1) determine the impact of climate change on national fisheries and (2) quantify the national-scale benefits of implementing climate-adaptive fisheries reforms. Management reforms accounting for shifting productivity and shifting distributions would yield higher catch and profits in the future relative to today for 60–65% of countries under the two least severe climate scenarios but for only 35% of countries under the most severe scenario. Furthermore, these management reforms would yield higher cumulative catch and profits than business-as-usual management for nearly all countries under the two least severe climate scenarios but would yield lower cumulative catch for 40% of countries under the most severe scenario. Fortunately, perfect fisheries management is not necessary to achieve these benefits: transboundary cooperation with 5-year intervals between adaptive interventions would result in comparable outcomes. However, the ability for realistic management reforms to offset the negative impacts of climate change is bounded by changes in underlying biological productivity. Although realistic reforms could generate higher catch and profits for 23–50% of countries experiencing reductions in productivity, the remaining countries would need to develop, expand, and reform aquaculture and other food production sectors to offset losses in capture fisheries. Still, climate-adaptive management is more profitable than business-as-usual management in all countries and we provide guidance on implementing–and achieving the benefits of–climate-adaptive fisheries reform along a gradient of scientific, management, and enforcement capacities.

Models of human dimensions of fisheries are important to understanding and predicting how fishing industries respond to changes in marine ecosystems and management institutions. Advances in computation have made it possible to construct agent-based models (ABMs)—which explicitly describe the behaviour of individual people, firms or vessels in order to understand and predict their aggregate behaviours. ABMs are widely used for both academic and applied purposes in many settings including finance, urban planning and the military, but are not yet mainstream in fisheries science and management, despite a growing literature. ABMs are well suited to understanding emergent consequences of fisher interactions, heterogeneity and bounded rationality, especially in complex ecological, social and institutional contexts. For these reasons, we argue that ABMs of human behaviour can contribute significantly to human dimensions of fisheries in three areas: (a) understanding interactions between multiple management institutions; (b) incorporating cognitive and behavioural sciences into fisheries science and practice; and (c) understanding and projecting the social consequences of management institutions. We provide simple examples illustrating the potential for ABMs in each of these areas, using conceptual (“toy”) versions of the POSEIDON model. We argue that salient strategic advances in these areas could pave the way for increased tactical use of ABMs in fishery management settings. We review common ABM development and application challenges, with the aim of providing guidance to beginning ABM developers and users studying human dimensions of fisheries.

Climate change is driving fishery stocks out of their historical ranges. Along with the management challenge of species entering new jurisdictions, the exit of species from countries’ waters poses distinct threats to those resources and the economies that depend on them. We show that this risk is particularly acute in the tropics, where projected exits are highest and entries are fewest. We find that existing policy frameworks are poorly equipped for this challenge, and we suggest a way forward that draws on climate policy.

Two of the largest protected areas on earth are U.S. National Monuments in the Pacific Ocean. Numerous claims have been made about the impacts of these protected areas on the fishing industry, but there has been no ex post empirical evaluation of their effects. We use administrative data documenting individual fishing events to evaluate the economic impact of the expansion of these two monuments on the Hawaii longline fishing fleet. Surprisingly, catch and catch-per-unit-effort are higher since the expansions began. To disentangle the causal effect of the expansions from confounding factors, we use unaffected control fisheries to perform a difference-in-differences analysis. We find that the monument expansions had little, if any, negative impacts on the fishing industry, corroborating ecological models that have predicted minimal impacts from closing large parts of the Pacific Ocean to fishing.

Small-scale fisheries are an important livelihood and primary protein source for coastal communities in many of the poorest regions in the world, yet many are overfished and thus require effective and scalable management solutions. Positive ecological and socioeconomic responses to management typically lag behind immediate costs borne by fishers from fishing pressure reductions necessary for fisheries recovery. These short-term costs challenge the long-term success of these interventions. However, social marketing may increase perceptions of management benefits before ecological and socioeconomic benefits are fully realized, driving new social norms and ultimately long-term sustainable behavior change. By conducting underwater visual surveys to quantify ecological conditions and by conducting household surveys with community members to quantify their perceptions of management support and socioeconomic conditions, we assessed the impact of a standardized small-scale fisheries management intervention that was implemented across 41 sites in Brazil, Indonesia, and the Philippines. The intervention combines TURF reserves (community-based territorial use rights for fishing coupled with no-take marine reserves) with locally tailored social-marketing behavior change campaigns. Leveraging data across 22 indicators and 4 survey types, along with data from 3 control sites, we found that ecological and socioeconomic impacts varied and that communities supported the intervention and were already changing their fishing practices. These results suggest that communities were developing new social norms and fishing more sustainably before long-term ecological and socioeconomic benefits of fisheries management materialized.

Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.

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.