Publications

Fisheries managers seek to maintain sustainable fisheries production, but successful management often requires the pursuit of multiple biological, ecological, and socioeconomic objectives simultaneously. Fisheries managers must choose among a broad range of harvest control methods (HCMs) to meet management objectives. This review identifies strengths and weaknesses of eight HCMs and evaluates their ability to meet a multitude of common biological, ecological, and socioeconomic management objectives such as protecting spawning biomass, reducing bycatch, and sustaining fishers’ profit. Evidence suggests that individual HCMs often fail to meet management objectives and may unintentionally create incentives to race to fish, discard catch and overcapitalize fishing operations. These limitations can be overcome by strategically combining multiple controls or incorporating rights-based and spatial management.

Data from 4,713 fisheries worldwide, representing 78% of global reported fish catch, are analyzed to estimate the status, trends, and benefits of alternative approaches to recovering depleted fisheries. For each fishery, we estimate current biological status and forecast the impacts of contrasting management regimes on catch, profit, and biomass of fish in the sea. We estimate unique recovery targets and trajectories for each fishery, calculate the year-by-year effects of alternative recovery approaches, and model how alternative institutional reforms affect recovery outcomes. Current status is highly heterogeneous—the median fishery is in poor health (overfished, with further overfishing occurring), although 32% of fisheries are in good biological, although not necessarily economic, condition. Our business-as-usual scenario projects further divergence and continued collapse for many of the world’s fisheries. Applying sound management reforms to global fisheries in our dataset could generate annual increases exceeding 16 million metric tons (MMT) in catch, $53 billion in profit, and 619 MMT in biomass relative to business as usual. We also find that, with appropriate reforms, recovery can happen quickly, with the median fishery taking under 10 y to reach recovery targets. Our results show that commonsense reforms to fishery management would dramatically improve overall fish abundance while increasing food security and profits.

Marine protected areas (MPAs) are a commonly applied solution to coral reef degradation, yet coral reefs continue to decline worldwide. We argue that expanding the range of MPAs to include degraded reefs (DR-MPA) could help reverse this trend. This approach requires new ecological criteria for MPA design, siting, and management. Rather than focusing solely on preserving healthy reefs, our approach focuses on the potential for biodiversity recovery and renewal of ecosystem services. The new criteria would help identify sites with the highest potential for recovery and the greatest resistance to future threats (e.g., increased temperature and acidification) and sites that contribute to MPA connectivity. The DR-MPA approach is a compliment rather than a substitute for traditional MPA design approaches. We believe that the DR-MPA approach can enhance the natural, or restoration-assisted, recovery of DRs and their ecosystem services; increase total reef area available for protection; promote more resilient and better-connected MPA networks; and improve conditions for human communities dependent on MPA ecosystem services.

Understanding changes in productivity for populationsof exploited marine fish is important for appropriatemanagement and conservation. Britten et al. (1) showthat, on average, the productivity of fish stocks havedeclined 3% per decade. This figure was an unweightedmean, and therefore gave equal weight to all stocks,regardless of size. An unweighted mean is a useful mea-sure of changing productivity, particularly when consid-ering conservation of individual stocks. However, foodsecurity is a central concern for many countries border-ing the ocean, so we should also ask, “How can changesin productivity influence the total biomass in the oceanand the total catch derived from that biomass?”To explore this question, I repeated Britten et al.’sanalysis (1) with the 224 stocks used by Szuwalski et al.(2) from the RAM Legacy Stock Assessment Database.I calculated the average decadal change in productivity(Rmax) over all stocks weighted by the average bio-mass of the stock and then by average catch. Weight-ing changes in productivity by biomass essentiallyremoved the negative trend in productivity (−0.06%average decadal change). Weighting changes in pro-ductivity by the average catch produced a positivetrend in productivity (+1%). This finding suggests thatthe net productive capacity of the ocean has changedvery little over time (at least for the stocks in the anal-ysis) and that productivity has increased for the stocksfrom which most catch in the RAM database is de-rived. Reproducing figure 1 of ref. 1 with changes inproductivity weighted by catch highlights that a fewLMEs account for a large proportion of the catch andmost LMEs have net positive changes in productivity(Fig. 1).

Well-managed fisheries support healthy ocean ecosystems, coastal livelihoods and food security for millions of people. However, many communities lack the resources to implement effective fisheries management. No-take marine reserves are a ubiquitous management intervention that provide conservation benefits and under certain circumstances can provide long-term fishery benefits as a result of larval and adult emigration from reserve boundaries. But, support for marine reserves by fishery participants is often limited due to short-term economic impacts resulting from foregone yields. In this study, we examine the timing and magnitude of economic impacts of marine reserves by utilizing a novel metric that discounts future economic benefits of enhanced productivity resulting from reserve protection. We ask under what circumstances long-term benefits outweigh short-term impacts of marine reserve implementation. We simulate fisheries for six species commonly caught in coastal environments and show that while conservation benefits accrue rapidly, more than a decade is often required to provide net fisheries benefits, even under circumstances favourable for reserves. We explore a suite of strategies for mitigating these short-term economic losses, including flexible reserve designs, loans and enhanced ex-vessel revenues. Results indicate that market-based incentives show promise to offset short-term economic losses. Our findings highlight the importance of understanding and communicating likely outcomes from marine reserve implementation and the need to engage supply chain actors to incentivize marine conservation that minimizes impacts to fishermen.

Effective enforcement can reduce the impacts of illegal, unregulated, and unreported (IUU) fishing, resulting in numerous economic, ecological, and social benefits. However, resource managers in small-scale fisheries often lack the expertise and financial resources required to design and implement an effective enforcement system. Here, a bio-economic model is developed to investigate optimal levels of fishery enforcement and financing mechanisms available to recover costs of enforcement. The model is parameterized to represent a small-scale Caribbean lobster fishery, and optimal fishery enforcement levels for three different stakeholder archetypes are considered: (1) a fishing industry only; (2) a dive tourism industry only; and (3) fishing and dive tourism industries. For the illustrative small-scale fishery presented, the optimal level of fishery enforcement decreases with increasing levels of biomass, and is higher when a dive tourism industry is present. Results also indicate that costs of fisheries enforcement can be recovered through a suite of financing mechanisms. However, the timescale over which financing becomes sustainable will depend largely on the current status of the fishery resource. This study may serve as a framework that can be used by resource managers to help design and finance economically optimal fisheries enforcement systems.

This paper examines the temperature-mortality relationship over the course of the twentieth-century United States both for its own interest and to identify potentially useful adaptations for coming decades. There are three primary findings. First, the mortality impact of days with mean temperature exceeding 80°F declined by 75 percent. Almost the entire decline occurred after 1960. Second, the diffusion of residential air conditioning explains essentially the entire decline in hot day–related fatalities. Third, using Dubin and McFadden’s discrete-continuous model, the present value of US consumer surplus from the introduction of residential air conditioning is estimated to be $85–$185 billion (2012 dollars).

The population of red spiny lobster (Panulirus penicillatus) around the Galapagos Islands has supported a fishery since the 1960s. However, conservation concerns have been raised given signs of over-exploitation observed during the mid-2000s, including decreasing trends in catch per unit effort (CPUE), yield, and profitability. We developed an integrated, size-structured assessment method to estimate trends in fishing mortality, recruitment, and mature biomass. A posterior distribution of spawning potential ratio (SPR) in 2011 was calculated using Bayesian methods and had a median of 44%, which is higher than most commonly used reference points (e.g. SPR = 40%). However, there are uncertainties in our estimates and continued monitoring with standardized data collection protocols should be a priority for future work in this fishery. Management should work toward establishing science-based management strategies that consider both the needs of fishing communities and the imperative to conserve unique ecosystems such as the Galapagos Islands.

The potential influence of climate change on the future distribution and abundance of fish (and therefore commercial fisheries and food security) is increasingly recognized in the fishery management community. A changing climate will likely have differing effects on different species; some will flourish, some will flounder. Management targets for fishing mortality and spawning biomass are often calculated by assuming stationary population processes, but under climate change, this assumption may be violated. Non-stationary population processes can introduce bias into estimates of biomass from stock assessments and calculations of target fishing mortalities and biomasses. However, few accepted frameworks exist for incorporating the changing influence of the environment on exploited populations into management strategies. Identifying changes in population processes due to environmental influences is important in order to enable climate-enhanced management strategy evaluations to elucidate the potential benefits and costs of changing management targets. Cost/benefit analyses will also be useful when coincidentally caught species respond differently to environmental change.

The debate has reemerged about the prevalence of “ocean calamities” (Duarte et al. 2015a, 2015b, Jacquet et al. 2015)—defined by Duarte and colleagues (2015a) as human-caused “disruptive changes to ocean ecosystems that have profound impacts and that are widespread and global in scope.” Two issues form the debate's core: First, how should we interpret circumstantial evidence in data-poor situations? Second, what is the role of the precautionary approach in ocean science and policy? We argue that prior information—even when circumstantial—should not be ignored and that Bayes’ theorem guides its incorporation. We agree with Duarte and colleagues (2015b) that precautionary approaches belong firmly in the realm of policy, although they are informed by science. Finally, we suggest abandoning “ocean calamities” as a scientific concept, because it entangles science and policy questions in a way that could introduce sociopolitical biases to scientific questions.

The ocean-calamities debate

Duarte and colleagues (2015a, 2015b) argue that the evidence for many claimed ocean calamities (e.g., harmful algal blooms and jellyfish blooms) is equivocal, at best. They also suggest (as others have) that incentives for sensationalism could be injecting bias into science and reporting—violating the principles of objective, evidence-driven analysis. In contrast, Jacquet and colleagues (2015) argue that enough evidence of severe human impacts on marine ecosystems already exists to justify broad concern and sweeping action, even if this evidence is not as strong as we would like it to be. In waiting to satisfy higher standards of proof, we could miss opportunities to prevent irreversible damage. This viewpoint, too, has been expressed before (e.g., Pauly 2013). For a range of issues, there are specific disagreements over the strengths and types of existing evidence, the strengths and directions of sociopolitical biases driven by scientific and journalistic incentives, and how precautionary approaches in addressing ocean calamities should be applied.

The introduction of property rights to manage common-pool resources is often met with opposition from some incumbent users, despite evidence of large aggregate increases in resource rent. We introduce an analytical model with firm heterogeneity to distinguish between traditional resource rent, which accrues to all owners, and inframarginal rent, which accrues to those with high skill. We show that, in the presence of skill heterogeneity, some current users (namely those with the highest skill) may prefer common-pool management, despite large aggregate increases in rents due to rationalization. Whether the transition to property rights is Pareto improving hinges critically on the initial allocation of rights, because inframarginal rents may be lower under property rights than limited entry. In our application to an important US fishery, property rights generate a ten-fold increase in market capitalization and a doubling in the present value of the resource, but without substantial free grandfathering, the top harvesters would rationally oppose the transition to property rights.

Food security, economic opportunities, and other benefits provided by a healthy ocean are in jeopardy because of years of overexploitation of many fisheries, and the challenges will intensify in many locales as climate and the environment continue to change. The good news is that solutions are gaining traction. Mandates to end overfishing that use scientifically determined catch limits and rights-based approaches to fishery management have produced impressive results in ending overfishing and recovering depleted stocks. Similarly, spatial protections, such as fully protected marine reserves, are increasing the diversity, size, and abundance of species within reserves; some of that bounty reaches fished areas outside of them. We review the effects of combining catch limits, rights-based fisheries approaches, and establishment of marine reserves and discuss additional advantages of these combined solutions in securing sustainable and profitable fisheries, community goals, and healthy ecosystems. This paper highlights the contribution of emerging science-based solutions and the steps needed to replicate and scale these successes. Triple-wins for the environment, the economy, and society can be achieved through integrated fisheries management and protection as conscious steps toward reversing the current degradation of our ocean’s living resources.

Marine Protected Areas (MPAs) are widely considered as useful tools to achieve both conservation and resource management goals. They have the potential to produce a wide array of positive socio-ecological effects. Their effectiveness, however, varies dramatically. The sources of this variability are numerous and, in some cases, quite well studied. Yet, a significant portion of the variability in MPAs effectiveness still remains unexplained. MPAs, due to a number of intrinsic features, can be considered “organizational systems”, a definition recognizing the fact that 1) their effectiveness can be influenced by their own organizational dimensions and 2) they could be analyzed employing the typical tools provided by ‘Organization Science’ (hereafter OS). Here we analyze the available literature on MPAs on a worldwide scale to explore whether and how the principles of OS have been used as a scientific basis for the evaluation of MPA effectiveness. We found that no study explicitly used a comprehensive OS framework for evaluating effectiveness in the context of MPAs. Just 20 studies considered some organizational dimensions in their analysis (e.g. professionalism of the organization members, vision, goals, strategy and networking), but not in a comprehensive manner. The outputs of our review stress the limited use of the OS methodologies and principles in the context of MPAs so far. We posit that there is a significant potential for new insights in MPA science thanks to a more integrated implementation of an OS framework for the interpretation and improvement of MPA socio-ecological effectiveness.

Multilevel societies, containing hierarchically nested social levels, are remarkable social structures whose origins are unclear. The social relationships of sperm whales are organized in a multilevel society with an upper level composed of clans of individuals communicating using similar patterns of clicks (codas). Using agent-based models informed by an 18-year empirical study, we show that clans are unlikely products of stochastic processes (genetic or cultural drift) but likely originate from cultural transmission via biased social learning of codas. Distinct clusters of individuals with similar acoustic repertoires, mirroring the empirical clans, emerge when whales learn preferentially the most common codas (conformism) from behaviourally similar individuals (homophily). Cultural transmission seems key in the partitioning of sperm whales into sympatric clans. These findings suggest that processes similar to those that generate complex human cultures could not only be at play in non-human societies but also create multilevel social structures in the wild.

Locally-established marine protected areas (MPAs) have been proven to achieve local-scale fisheries and conservation objectives. However, since many of these MPAs were not designed to form ecologically-connected networks, their contributions to broader-scale goals such as complementarity and connectivity can be limited. In contrast, integrated networks of MPAs designed with systematic conservation planning are assumed to be more effective—ecologically, socially, and economically—than collections of locally-established MPAs. There is, however, little empirical evidence that clearly demonstrates the supposed advantages of systematic MPA networks. A key reason is the poor record of implementation of systematic plans attributable to lack of local buy-in. An intermediate scenario for the expansion of MPAs is scaling up of local decisions, whereby locally-driven MPA initiatives are coordinated through collaborative partnerships among local governments and their communities. Coordination has the potential to extend the benefits of individual MPAs and perhaps to approach the potential benefits offered by systematic MPA networks. We evaluated the benefits of scaling up local MPAs to form networks by simulating seven expansion scenarios for MPAs in the Verde Island Passage, central Philippines. The scenarios were: uncoordinated community-based establishment of MPAs; two scenarios reflecting different levels of coordinated MPA expansion through collaborative partnerships; and four scenarios guided by systematic conservation planning with different contexts for governance. For each scenario, we measured benefits through time in terms of achievement of objectives for representation of marine habitats. We found that: in any governance context, systematic networks were more efficient than non-systematic ones; systematic networks were more efficient in broader governance contexts; and, contrary to expectations but with caveats, the uncoordinated scenario was slightly more efficient than the coordinated scenarios. Overall, however, coordinated MPA networks have the potential to be more efficient than the uncoordinated ones, especially when coordinated planning uses systematic methods.

Size-structured assessment models require size data to be binned, but it is unclear how a specified bin width can impact the ability of an assessment to estimate quantities important in management. Biases in estimated mature biomass are demonstrated here when increasing the bin width using a simulation framework based on the Pribilof Islands red king crab (PIRKC) assessment. Several potential sources of bias were explored through simulation. The bias was removed by applying an alternative assessment method which used a finer approximation of the integral representing the probability of a crab molting from one size bin. Trade-offs exist at both sides of the bin width spectrum. Precision and model stability may suffer when bin width is too large; slowed parameter estimation and problems fitting multinomial likelihoods to length frequency data may appear when bin widths are too small. Simulation studies (like the one presented here) are useful for identifying optimal bin width for management related tasks.

Interest in mining the deep seabed is not new; however, recent technological advances and increasing global demand for metals and rare-earth elements may make it economically viable in the near future (1). Since 2001, the International Seabed Authority (ISA) has granted 26 contracts (18 in the last 4 years) to explore for minerals on the deep seabed, encompassing ∼1 million km² in the Pacific, Atlantic, and Indian Oceans in areas beyond national jurisdiction (2). However, as fragile habitat structures and extremely slow recovery rates leave diverse deep-sea communities vulnerable to physical disturbances such as those caused by mining (3), the current regulatory framework could be improved. We offer recommendations to support the application of a precautionary approach when the ISA meets later this July.

Balanced harvesting – harvesting all species and sizes in an ecosystem in proportion to their productivity – is a fisheries management strategy that has been suggested recently to increase yields, while reducing overall ecosystem impact. However, some aspects of balanced harvesting are controversial, including its call for extensive harvesting of juveniles and forage fish. Balanced harvesting also calls for targeting species and size-classes that are not currently marketable, possibly at a significant economic cost. Some have argued that this cost is outweighed by the ecological benefits of maintaining the ecosystem size and trophic structures and by the benefits of extra yield for food security. There is broad consensus that balanced harvesting would require major changes to fishery management institutions and consumer behaviour, and it is unclear to what extent it is physically possible with current technologies. For this reason, we argue that steps to implement balanced harvesting are difficult to justify until the case for it is more clearly resolved. We outline some of the pivotal questions that must be answered to make a convincing case for or against balanced harvesting, many of which can be answered empirically. In identifying these questions, we hope to offer a constructive path forward in resolving some of the key issues in the balanced harvesting debate.

Understanding the interaction between fish-ing and natural variations in productivity isa central question in fisheries management.Essington et al. (1) advance the discussionon drivers of forage fish dynamics by high-lighting the role of natural decreases in bio-mass collapses. A key conclusion of theirwork is that fishing increases the magnitudeand frequency of collapse in biomass. Moreintense fishing necessarily results in fewerfish; however, the higher exploitation ratescommonly seen as forage fish biomass de-clines do not always mean that fishing pre-cipitated collapses in productivity.Using a biomass threshold to identifywhen collapses occur might be appropriateif biomass were the key driver of productiv-ity (i.e., a stock–recruitment relationship ex-ists). However, this is untrue for 88% of thestocks in Essington et al. (1) (demonstratedin ref. 2), a point that the authors make. So,changes in recruitment must be comparedwith exploitation patterns to explore the in-fluence of fishing on productivity. To achievethis, we applied a break-point algorithm (3)to the time series’ of recruitment for thestocks in Essington et al. (1) to identify pe-riods of lower productivity (see Fig. 1 forexamples). Recruitment for 23 stocks shiftedto low productivity at some point in theirhistory and only one of those stocks appearedto have a repeatable stock–recruit relationship.The median relative exploitation pressure forthese stocks before a shift in productivity wassignificantly less than exploitation pressure af-ter (Fig. 1, Left; P < 0.05), suggesting that highexploitation does not precipitate collapse inrecruitment. The relative exploitation ratebefore a collapse in recruitment was not sig-nificantly related to the magnitude of thecollapse. Furthermore, recovery (e.g., NorthSea herring in Fig. 1) was generally not pre-ceded by increasing biomass or decreasedexploitation; biomass increased and ex-ploitation decreased only after recruitmentincreased again (Fig. 1, Right). These obser-vations suggest that fishing plays little rolein the dynamics of forage fish productivity.

The science of designing a marine protected areas network is rapidly developing. However, translating the design principles for a data-limited situation is a challenge. The planning design that works perfectly in a developed country setting may not be readily applicable to a developing and emerging country setting because of constraints on data availability and social complexity. Using available global databases and local knowledge, a participatory-based, semi-quantitative framework for selecting suitable sites for protection in the Southern Negros Marine Key Biodiversity Area in the Philippines was implemented. The framework involved the accounting of marine resources; identifying areas of biodiversity and fisheries importance; and determining land- and sea-based threats to marine biodiversity, ecosystems, and its uses. Various initiatives that could engage the municipalities in Southern Negros in the networking process were identified.