Publications

Marine spatial planning (MSP) is an emerging responsibility of resource managers around the United States and elsewhere. A key proposed advantage of MSP is that it makes tradeoffs in resource use and sector (stakeholder group) values explicit, but doing so requires tools to assess tradeoffs. We extended tradeoff analyses from economics to simultaneously assess multiple ecosystem services and the values they provide to sectors using a robust, quantitative, and transparent framework. We used the framework to assess potential conflicts among offshore wind energy, commercial fishing, and whale-watching sectors in Massachusetts and identify and quantify the value from choosing optimal wind farm designs that minimize conflicts among these sectors. Most notably, we show that using MSP over conventional planning could prevent >$1 million dollars in losses to the incumbent fishery and whale-watching sectors and could generate >$10 billion in extra value to the energy sector. The value of MSP increased with the greater the number of sectors considered and the larger the area under management. Importantly, the framework can be applied even when sectors are not measured in dollars (e.g., conservation). Making tradeoffs explicit improves transparency in decision-making, helps avoid unnecessary conflicts attributable to perceived but weak tradeoffs, and focuses debate on finding the most efficient solutions to mitigate real tradeoffs and maximize sector values. Our analysis demonstrates the utility, feasibility, and value of MSP and provides timely support for the management transitions needed for society to address the challenges of an increasingly crowded ocean environment.

The ecologically and socio-economically important marine ecosystems of Europe are facing severe threats from a variety of human impacts. To mitigate and potentially reverse some of these impacts, the European Union (EU) has mandated the implementation of the Marine Strategy Framework Directive (MSFD) in order to achieve Good Environmental Status (GES) in EU waters by 2020. The primary initiative for achieving GES is the implementation of coherent networks of marine protected areas (MPAs). Marine reserves are an important type of MPA in which no extraction is allowed, but their usefulness depends upon a number of ecological, management, and political factors. This paper provides a synthesis of the ecological effects of existing European marine reserves and the factors (social and ecological) underlying their effectiveness. Results show that existing European marine reserves foster significant positive increases in key biological variables (density, biomass, body size, and species richness) compared with areas receiving less protection, a pattern mirrored by marine reserves around the globe. For marine reserves to achieve their ecological and social goals, however, they must be designed, managed, and enforced properly. In addition, identifying whether protected areas are ecologically connected as a network, as well as where new MPAs should be established according to the MSFD, requires information on the connectivity of populations across large areas. The adoption of the MSFD demonstrates willingness to achieve the long-term protection of Europe's marine ecosystems, but whether the political will (local, regional, and continent wide) is strong enough to see its mandates through remains to be seen. Although the MSFD does not explicitly require marine reserves, an important step towards the protection of Europe's marine ecosystems is the establishment of marine reserves within wider-use MPAs as connected networks across large spatial scales.

Despite the International Whaling Commission's (IWC) moratorium on commercial whaling beginning in 1986, the number of whales taken has more than doubled since the early 1990s. Almost 2,000 whales are now harvested each year — roughly 1,000 for 'scientific purposes' (by Japan), 600 by countries that object to the ban (Norway and Iceland), and 350 for subsistence (mainly by Denmark, Russia and the United States)¹. Many populations of large whales have been severely depleted and continue to be threatened by commercial whaling².

The persistence of largely unregulated whaling has sparked heated debate about whether the IWC, long hamstrung by management and ethics issues, should again permit formally sanctioned whaling. In 2010, some anti-whaling nations proposed a compromise: establishing quotas for sanctioned whaling that would still reduce the overall number of whales taken. After much wrangling, the deal fell through — largely because many anti-whaling groups had a fundamental problem with setting quotas at all, because they felt that these would appear to legitimize commercial whaling. Some people blame Japan for the deal's collapse, because the country refused to sign up to a proposed zero quota on whale catches in the Southern Ocean.

We propose an alternative path forward that could break the deadlock: quotas that can be bought and sold, creating a market that would be economically, ecologically and socially viable for whalers and whales alike. Because conservationists could bid for quotas, whalers could profit from whales even without harvesting the animals. A market would therefore open the door to reducing mortality without needing to battle over whether whaling is honourable or shameful.

Increasing levels of fisheries collapse are now widely believed to be the consequence of ineffective centralized management of the common pool. In theory, realigning incentives for ecologically sustainable and economically prosperous fisheries requires assigning property rights to the resource, which will then encourage owners to internalize the effects on sustainability of current resource management decisions. In fisheries, property rights can be assigned in a variety of ways, including rights to harvest a certain fraction of the allowable catch (individual transferable quotas, ITQs), rights to exclusive harvest within a given geographic region (territorial use rights fisheries, TURFs), and rights to manage a resource stock collaboratively through a group with well-defined membership (cooperatives). The relative performance of each of these approaches will, at least in principle, depend on the specifics of the fishery in question, suggesting that correctly designing property rights institutions to match the fishery context is crucial to success.

Recent reports suggest that many well-assessed fisheries in developed countries are moving toward sustainability. We examined whether the same conclusion holds for fisheries lacking formal assessment, which comprise >80% of global catch. We developed a method using species’ life-history, catch, and fishery development data to estimate the status of thousands of unassessed fisheries worldwide. We found that small unassessed fisheries are in substantially worse condition than assessed fisheries, but that large unassessed fisheries may be performing nearly as well as their assessed counterparts. Both small and large stocks, however, continue to decline; 64% of unassessed stocks could provide increased sustainable harvest if rebuilt. Our results suggest that global fishery recovery would simultaneously create increases in abundance (56%) and fishery yields (8 to 40%).

The global demand for protein from seafood – whether wild, caught or cultured, whether for direct consumption or as feed for livestock – is high and projected to continue growing. However, the ocean’s ability to meet this demand is uncertain due to either mismanagement or, in some cases, lack of management of marine fish stocks. Efforts to rebuild and recover the world’s fisheries will benefit from an improved understanding of the long-term economic benefits of recovering collapsed stocks, the trajectory and duration of different rebuilding approaches, variation in the value and timing of recovery for fisheries with different economic, biological, and regulatory characteristics, including identifying which fisheries are likely to benefit most from recovery, and the benefits of avoiding collapse in the first place. These questions are addressed using a dynamic bioeconomic optimisation model that explicitly accounts for economics, management, and ecology of size-structured exploited fish populations. Within this model framework, different management options (effort controls on small-, medium-, and large-sized fish) including management that optimises economic returns over a specified planning horizon are simulated and the consequences compared. The results show considerable economic gains from rebuilding fisheries, with magnitudes varying across fisheries.

The precarious state of many nearshore marine ecosystems has prompted the use of marine protected areas as a tool for management and conservation. However, there remains substantial debate over their design and, in particular, how to best account for the spatial dynamics of nearshore marine species. Many commercially important nearshore marine species are sedentary as adults, with limited home ranges. It is as larvae that they disperse greater distances, traveling with ocean currents sometimes hundreds of kilometers. As a result, these species exist in spatially complex systems of connected subpopulations. Here, we explicitly account for the mutual dependence of subpopulations and approach protected area design in terms of network robustness. Our goal is to characterize the topology of nearshore metapopulation networks and their response to perturbation, and to identify critical subpopulations whose protection would reduce the risk for stock collapse. We define metapopulation networks using realistic estimates of larval dispersal generated from ocean circulation simulations and spatially explicit metapopulation models, and we then explore their robustness using node-removal simulation experiments. Nearshore metapopulations show small-world network properties, and we identify a set of highly connected hub subpopulations whose removal maximally disrupts the metapopulation network. Protecting these subpopulations reduces the risk for systemic failure and stock collapse. Our focus on catastrophe avoidance provides a unique perspective for spatial marine planning and the design of marine protected areas.

Fish populations vary geographically in demography and life history due to environmental and ecological processes and in response to exploitation. However, population dynamic models and stock assessments, used to manage fisheries, rarely explicitly incorporate spatial variation to inform management decisions. Here, we describe extensive geographic variation in several demographic and life history characteristics (e.g., size structure, growth, survivorship, maturation, and sex change) of California sheephead (Semicossyphus pulcher), a temperate rocky reef fish targeted by recreational and commercial fisheries. Fish were sampled from nine locations throughout southern California in 2007–2008. We developed a dynamic size and age-structured model, parameterized separately for each location, to assess the potential cost or benefit in terms of fisheries yield and conservation objectives of changing minimum size limits and/or fishing mortality rates (compared to the status quo). Results indicate that managing populations individually, with location-specific regulations, could increase yield by over 26% while maintaining conservative levels of spawning biomass. While this local management approach would be challenging to implement in practice, we found statistically similar increases in yield could be achieved by dividing southern California into two separate management regions, reflecting geographic similarities in demography. To maximize yield, size limits should be increased by 90 mm in the northern region and held at current levels in the south. We also found that managing the fishery as one single stock (the status quo), but with a size limit 50 mm greater than the current regulations, could increase overall fishery yield by 15%. Increases in size limits are predicted to enhance fishery yield and may also have important ecological consequences for the predatory role of sheephead in kelp forests. This framework for incorporating demographic variation into fisheries models can be exported generally to other species and may aid in identifying the appropriate spatial scales for fisheries management.

Spatial management, including setting aside conservation areas, is central to curbing the global decline of biodiversity, but many threats originate from beyond the boundaries of conservation areas. This is a particular problem in marine systems, which are influenced by many activities on land. In addition, connections between land and sea support many species and ecological processes valued for conservation. Integrated land and sea conservation planning is therefore of utmost importance. We review the literature describing connections between land and sea and how they have been incorporated into conservation planning. Land-sea connections include land-sea processes, the natural flows occurring between realms; cross-system threats, which originate in one realm and affect another; and socioeconomic interactions associated with management decisions to maintain or restore land-sea processes and to prevent or mitigate cross-system threats. We highlight the need to explicitly incorporate land-sea connections in conservation planning and suggest ways of doing this through the use of a novel operational framework for integrated land-sea planning. On the basis of expert surveys and a literature review, we also identify those aspects of conservation planning for which improved integration between land and sea is most needed.

It has been proposed that changes in global climate have been responsible for episodes of widespread violence and even the collapse of civilizations^1,2. Yet previous studies have not shown that violence can be attributed to the global climate, only that random weather events might be correlated with conflict in some cases^3,4,5,6,7. Here we directly associate planetary-scale climate changes with global patterns of civil conflict by examining the dominant interannual mode of the modern climate^8,9,10, the El Niño/Southern Oscillation (ENSO). Historians have argued that ENSO may have driven global patterns of civil conflict in the distant past^11,12,13, a hypothesis that we extend to the modern era and test quantitatively. Using data from 1950 to 2004, we show that the probability of new civil conflicts arising throughout the tropics doubles during El Niño years relative to La Niña years. This result, which indicates that ENSO may have had a role in 21% of all civil conflicts since 1950, is the first demonstration that the stability of modern societies relates strongly to the global climate.

Policies are arising around the world, most recently in the United States, that mandate the implementation of marine spatial planning as a practical pathway towards ecosystem-based management. In the new United States ocean policy, and several other cases around the globe, ecosystem services are at the core of marine spatial planning, but there is little guidance on how ecosystem services should be measured, making it hard to implement this new approach. A new framework is shown here for practical, rigorous ecosystem service measurement that highlights contributions from both natural and social systems. The novel three-step framework addresses traditional shortcomings of an ecosystem services approach by giving managers and scientists the tools to assess and track: (1) the condition of the ecosystem (supply metrics), (2) the amount of ocean resources actually used or enjoyed by people (service metrics), and (3) people's preference for that level of service (value metrics). This framework will allow real world progress on marine spatial planning to happen quickly, and with a greater chance for success.

Intertidal crabs in diverse habitats worldwide release larvae synchronously during nocturnal spring high tides. This expedites seaward transport of the larvae to beyond high density areas of predatory fishes under the cover of darkness. We found that 4 species of intertidal crabs along the west coast of the USA shared this reproductive timing pattern. As in other mixed semidiurnal tidal regimes, biweekly patterns of larval release were more closely synchronized with the tidal amplitude cycle than the lunar cycle, and some crabs released larvae in daylight. However, unlike other places in the world, larval release was weakly synchronized to environmental cycles regardless of interspecific differences in vertical distributions on the shore. We provide evidence that weak synchrony in the timing of larval release in upwelling regimes can result from exposure to environmental variation over long incubation periods of externally brooded embryos. According to the prevailing paradigm, weaker synchrony in the timing of larval release will increase predation by planktivorous fishes in upwelling regimes. Weak synchrony in the timing of larval release should increase larval mortality in a wide array of animals that brood embryos in the intertidal zone, regardless of the selective force operating, and it could contribute to recruitment limitation in upwelling regimes.

Regulation of fisheries using spatial property rights can alleviate competition for high-value patches that hinders economic efficiency in quota-based, rights-based, and open-access management programs. However, efficiency gains erode when delineation of spatial rights constitutes incomplete ownership of the resource, thereby degrading its local value and promoting overexploitation. Incomplete ownership may be particularly prevalent in the spatial management of mobile fishery species. We developed a game-theoretic bioeconomic model of spatial property rights representing territorial user rights fisheries (TURF) management of nearshore marine fish and invertebrate species with mobile adult and larval life history stages. Strategic responses by fisheries in neighboring management units result in overexploitation of the stock and reduced yields for each fishery compared with those attainable without resource mobility or with coordination or sole control in fishing effort. High dispersal potential of the larval stage, a common trait among nearshore fishery species, coupled with scaling of management units to only capture adult mobility, a common characteristic of many nearshore TURF programs, in particular substantially reduced stock levels and yields. In a case study of hypothetical TURF programs of nearshore fish and invertebrate species, management units needed to be tens of kilometers in alongshore length to minimize larval export and generate reasonable returns to fisheries. Cooperation and quota regulations represent solutions to the problem that need to be quantified in cost and integrated into the determination of the acceptability of spatial property rights management of fisheries.

The indirect, ecosystem-level consequences of ocean fishing, and particularly the mechanisms driving them, are poorly understood. Most studies focus on density-mediated trophic cascades, where removal of predators alternately causes increases and decreases in abundances of lower trophic levels. However, cascades could also be driven by where and when prey forage rather than solely by prey abundance. Over a large gradient of fishing intensity in the central Pacific's remote northern Line Islands, including a nearly pristine, baseline coral reef system, we found that changes in predation risk elicit strong behavioral responses in foraging patterns across multiple prey fish species. These responses were observed as a function of both short-term (“acute”) risk and longer-term (“chronic”) risk, as well as when prey were exposed to model predators to isolate the effect of perceived predation risk from other potentially confounding factors. Compared to numerical prey responses, antipredator behavioral responses such as these can potentially have far greater net impacts (by occurring over entire assemblages) and operate over shorter temporal scales (with potentially instantaneous response times) in transmitting top-down effects. A rich body of literature exists on both the direct effects of human removal of predators from ecosystems and predators' effects on prey behavior. Our results draw together these lines of research and provide the first empirical evidence that large-scale human removal of predators from a natural ecosystem indirectly alters prey behavior. These behavioral changes may, in turn, drive previously unsuspected alterations in reef food webs.

As human impacts cause ecosystem-wide changes in the oceans, the need to protect and restore marine resources has led to increasing calls for and establishment of marine reserves. Scientific information about marine reserves has multiplied over the last decade, providing useful knowledge about this tool for resource users, managers, policy makers, and the general public. This information must be conveyed to nonscientists in a nontechnical, credible, and neutral format, but most scientists are not trained to communicate in this style or to develop effective strategies for sharing their scientific knowledge. Here, we present a case study from California, in which communicating scientific information during the process to establish marine reserves in the Channel Islands and along the California mainland coast expanded into an international communication effort. We discuss how to develop a strategy for communicating marine reserve science to diverse audiences and highlight the influence that effective science communication can have in discussions about marine management.

Marine protected areas (MPAs) that exclude fishing have been shown repeatedly to enhance the abundance, size, and diversity of species. These benefits, however, mean little to most marine species, because individual protected areas typically are small. To meet the larger-scale conservation challenges facing ocean ecosystems, several nations are expanding the benefits of individual protected areas by building networks of protected areas. Doing so successfully requires a detailed understanding of the ecological and physical characteristics of ocean ecosystems and the responses of humans to spatial closures. There has been enormous scientific interest in these topics, and frameworks for the design of MPA networks for meeting conservation and fishery management goals are emerging. Persistent in the literature is the perception of an inherent tradeoff between achieving conservation and fishery goals. Through a synthetic analysis across these conservation and bioeconomic studies, we construct guidelines for MPA network design that reduce or eliminate this tradeoff. We present size, spacing, location, and configuration guidelines for designing networks that simultaneously can enhance biological conservation and reduce fishery costs or even increase fishery yields and profits. Indeed, in some settings, a well-designed MPA network is critical to the optimal harvest strategy. When reserves benefit fisheries, the optimal area in reserves is moderately large (mode ≈30%). Assessing network design principals is limited currently by the absence of empirical data from large-scale networks. Emerging networks will soon rectify this constraint.

Marine reserve theory suggests that where large, productive populations are protected within no-take marine reserves, fished areas outside reserves will benefit through the spillover of larvae produced in the reserves. However, empirical evidence for larval export has been sparse. Here we use a simple idealized coastline model to estimate the expected magnitude and spatial scale of larval export from no-take marine reserves across a range of reserve sizes and larval dispersal scales. Results suggest that, given the magnitude of increased production typically found in marine reserves, benefits from larval export are nearly always large enough to offset increased mortality outside marine reserves due to displaced fishing effort. However, the proportional increase in recruitment at sites outside reserves is typically small, particularly for species with long-distance (on the order of hundreds of kilometers) larval dispersal distances, making it very difficult to detect in field studies. Enhanced recruitment due to export may be detected by sampling several sites at an appropriate range of distances from reserves or at sites downcurrent of reserves in systems with directional dispersal. A review of existing empirical evidence confirms the model's suggestion that detecting export may be difficult without an exceptionally large differential in production, short-distance larval dispersal relative to reserve size, directional dispersal, or a sampling scheme that encompasses a broad range of distances from the reserves.

The field of marine reserve science has matured greatly over the last decade, moving beyond studies of single reserves and beyond perspectives from single disciplines. This Special Feature exemplifies recent advances in marine reserve research, showing insights gained from synthetic studies of reserve networks, long-term changes within reserves, integration of social and ecological science research, and balance between reserve design for conservation as well as fishery and other commercial objectives. This rich body of research helps to inform conservation planning for marine ecosystems but also poses new challenges for further study, including how to best design integrated fisheries management and conservation systems, how to effectively evaluate the performance of entire reserve networks, and how to examine the complex coupling between ecological and socioeconomic responses to reserve networks.

The rapid increase in the science and implementation of marine protected areas (MPAs) around the world in the past 15 years is now being followed by similar increases in the science and application of marine ecosystem-based management (EBM). Despite important overlaps and some common goals, these two approaches have remained either separated in the literature and in conservation and management efforts or treated as if they are one and the same. In the cases when connections are acknowledged, there is often little assessment of if or how well MPAs can achieve specific EBM goals. Here we start by critically evaluating commonalities and differences between MPAs and EBM. Next, we use global analyses to show where and how much no-take marine reserves can be expected to contribute to EBM goals, specifically by reducing the cumulative impacts of stressors on ocean ecosystems. These analyses revealed large stretches of coastal oceans where reserves can play a major role in reducing cumulative impacts and thus improving overall ocean condition, at the same time highlighting the limitations of marine reserves as a single tool to achieve comprehensive EBM. Ultimately, better synergies between these two burgeoning approaches provide opportunities to greatly benefit ocean health.