[Show abstract][Hide abstract] ABSTRACT: As climatic changes and human uses intensify, resource managers and other decision makers are taking actions to either avoid or respond to ecosystem tipping points, or dramatic shifts in structure and function that are often costly and hard to reverse. Evidence indicates that explicitly addressing tipping points leads to improved management outcomes. Drawing on theory and examples from marine systems, we distill a set of seven principles to guide effective management in ecosystems with tipping points, derived from the best available science. These principles are based on observations that tipping points (1) are possible everywhere, (2) are associated with intense and/or multifaceted human use, (3) may be preceded by changes in early-warning indicators, (4) may redistribute benefits among stakeholders, (5) affect the relative costs of action and inaction, (6) suggest biologically informed management targets, and (7) often require an adaptive response to monitoring. We suggest that early action to preserve system resilience is likely more practical, affordable, and effective than late action to halt or reverse a tipping point. We articulate a conceptual approach to management focused on linking management targets to thresholds, tracking early-warning signals of ecosystem instability, and stepping up investment in monitoring and mitigation as the likelihood of dramatic ecosystem change increases. This approach can simplify and economize management by allowing decision makers to capitalize on the increasing value of precise information about threshold relationships when a system is closer to tipping or by ensuring that restoration effort is sufficient to tip a system into the desired regime.
[Show abstract][Hide abstract] ABSTRACT: Predators are critical components of ecosystems. Globally, conservation efforts have targeted depleted populations of top predators for legal protection, and in many cases, this protection has helped their recoveries. Where the recovery of individual species is the goal, these efforts can be seen as largely successful. From an ecosystem perspective, however, predator recovery can introduce significant new conservation and legal challenges. We highlight three types of conflicts created by a single-species focus: (1) recovering predator populations that increase competition with humans for the same prey, (2) new tradeoffs that emerge when protected predators consume protected prey, and (3) multiple predator populations that compete for the same limited prey. We use two food webs with parallel conservation challenges, the Northeast Pacific Ocean and the Greater Yellowstone ecosystem, to demonstrate legal/policy conflicts and the policy levers that exist to ameliorate conflicts. In some cases, scientific uncertainty about the ecological interaction hinders progress towards resolving conflicts. In others, available policy options are insufficient. In all cases, management decisions must be made in the face of an unknown future. We suggest a framework that incorporates multispecies science, policy tools, and tradeoff analyses into management.This article is protected by copyright. All rights reserved
Full-text · Article · May 2015 · Conservation Letters
[Show abstract][Hide abstract] ABSTRACT: Human activities in coastal and marine ecosystems provide a suite of benefits for people, but can also produce a number of stressors that can act additively, synergistically, or antagonistically to change ecosystem structure, function, and dynamics in ways that differ from single stressor responses. Scientific tools that can be used to evaluate the effects of multiple stressors are needed to assist decision making. In this paper, we review indicator selection methods and general approaches to assess indicator responses to multiple stressors and compare example ecosystem assessments. Recommendations are presented for choosing and assessing suites of indicators to characterize responses. Indicators should be chosen based upon defined criteria, conceptual models linking indicators to pressures and drivers, and defined strategic goals and ecological or management objectives. Indicators should be complementary and nonredundant, and they should integrate responses to multiple stressors and reflect the status of the ecosystem. An initial core set of indicators could include those that have been tested for the effects of climate and fishing and then expanded to include other pressures and ecosystem-specific, feature-pressure interactions. Identifying indicators and evaluating multiple stressors on marine ecosystems require a variety of approaches, such as empirical analyses, expert opinion, and model-based simulation. The goal is to identify a meaningful set of indicators that can be used to assist with the management of multiple types of human interactions with marine ecosystems.
No preview · Article · Dec 2014 · Oceanography (Washington D.C.)
[Show abstract][Hide abstract] ABSTRACT: Twenty-first century conservation is centered on negotiating trade-offs between the diverse needs of people and the needs of the other species constituting coupled human-natural ecosystems. Marine forage fishes, such as sardines, anchovies, and herring, are a nexus for such trade-offs because they are both central nodes in marine food webs and targeted by fisheries. An important example is Pacific herring, Clupea pallisii in the Northeast Pacific. Herring populations are subject to two distinct fisheries: one that harvests adults and one that harvests spawned eggs. We develop stochastic, age-structured models to assess the interaction between fisheries, herring populations, and the persistence of predators reliant on herring populations. We show that egg- and adult-fishing have asymmetric effects on herring population dynamics - herring stocks can withstand higher levels of egg harvest before becoming depleted. Second, ecosystem thresholds proposed to ensure the persistence of herring predators do not necessarily pose more stringent constraints on fisheries than conventional, fishery driven harvest guidelines. Our approach provides a general template to evaluate ecosystem trade-offs between stage-specific harvest practices in relation to environmental variability, the risk of fishery closures, and the risk of exceeding ecosystem thresholds intended to ensure conservation goals are met.
Full-text · Article · Nov 2014 · Scientific Reports
[Show abstract][Hide abstract] ABSTRACT: Management of marine ecosystems increasingly demands comprehensive and quantitative assessments of ocean health, but lacks a tool to do so. We applied the recently developed Ocean Health Index to assess ocean health in the relatively data-rich US west coast region. The overall region scored 71 out of 100, with sub-regions scoring from 65 (Washington) to 74 (Oregon). Highest scoring goals included tourism and recreation (99) and clean waters (87), while the lowest scoring goals were sense of place (48) and artisanal fishing opportunities (57). Surprisingly, even in this well-studied area data limitations precluded robust assessments of past trends in overall ocean health. Nonetheless, retrospective calculation of current status showed that many goals have declined, by up to 20%. In contrast, near-term future scores were on average 6% greater than current status across all goals and sub-regions. Application of hypothetical but realistic management scenarios illustrate how the Index can be used to predict and understand the tradeoffs among goals and consequences for overall ocean health. We illustrate and discuss how this index can be used to vet underlying assumptions and decisions with local stakeholders and decision-makers so that scores reflect regional knowledge, priorities and values. We also highlight the importance of ongoing and future monitoring that will provide robust data relevant to ocean health assessment.
[Show abstract][Hide abstract] ABSTRACT: As human population size and demand for seafood and other marine resources increase, understanding the influence of human activities in the ocean and on land becomes increasingly critical to the management and conservation of marine resources. In order to account for human influence on marine ecosystems while making management decisions, linkages between various anthropogenic pressures and ecosystem components need to be determined. Those linkages cannot be drawn until it is known how different pressures have been changing over time. This paper identifies indicators and develops time series for 22 anthropogenic pressures acting on the USA's portion of the California Current ecosystem. Time series suggest that seven pressures have decreased and two have increased over the short term, while five pressures were above and two pressures were below long-term means. Cumulative indices of anthropogenic pressures suggest a slight decrease in pressures in the 2000s compared to the preceding few decades. Dynamic factor analysis revealed four common trends that sufficiently explained the temporal variation found among all anthropogenic pressures. This reduced set of time series will be a useful tool to determine whether links exist between individual or multiple pressures and various ecosystem components.
Full-text · Article · Jun 2014 · Environmental Conservation
[Show abstract][Hide abstract] ABSTRACT: Simulation models are widely used to represent the dynamics of ecological systems. A common question with such models is how changes to a parameter value or functional form in the model alter the results. Some authors have chosen to answer that question using frequentist statistical hypothesis tests (e.g. ANOVA). This is inappropriate for two reasons. First, p-values are determined by statistical power (i.e. replication), which can be arbitrarily high in a simulation context, producing minuscule p-values regardless of the effect size. Second, the null hypothesis of no difference between treatments (e.g. parameter values) is known a priori to be false, invalidating the premise of the test. Use of p-values is troublesome (rather than simply irrelevant) because small p-values lend a false sense of importance to observed differences. We argue that modelers should abandon this practice and focus on evaluating the magnitude of differences between simulations.
[Show abstract][Hide abstract] ABSTRACT: Sustainable provision of seafood from wild-capture fisheries and mariculture is a fundamental component of healthy marine ecosystems and a major component of the Ocean Health Index. Here we critically review the food provision model of the Ocean Health Index, and explore the implications of knowledge gaps, scale of analysis, choice of reference points, measures of sustainability, and quality of input data. Global patterns for fisheries are positively related to human development and latitude, whereas patterns for mariculture are most closely associated with economic importance of seafood. Sensitivity analyses show that scores are robust to several model assumptions, but highly sensitive to choice of reference points and, for fisheries, extent of time series available to estimate landings. We show how results for sustainable seafood may be interpreted and used, and we evaluate which modifications show the greatest potential for improvements.
Full-text · Article · Nov 2013 · AMBIO A Journal of the Human Environment
[Show abstract][Hide abstract] ABSTRACT: As resource management efforts move towards more comprehensive approaches that span multiple sectors and stakeholder groups, decision makers are faced with the challenge of deciding how important each group is, and how much weight their concerns should have, when making decisions. These decisions must be made transparently if they are to have credibility. This paper describes a systematic approach to eliciting such preferences, illustrated through a regional application of the Ocean Health Index in the California Current. The Index provides an ideal case study as it includes a comprehensive set of goals designed to assess the benefits people derive from coasts and oceans. The approach leverages the strengths of two different methods for eliciting preferences, one based on random utility theory and the other on analytical deliberative methodologies. Results showed that the methods were accessible to individuals with diverse backgrounds and, in this case, revealed surprising consensus about fundamental values that may have been missed in deliberations around a specific action, rather than evaluating a spectrum of management priorities. Specifically, individuals, even extractive users, assigned higher weights to cultural and conservation goals compared to extractive ones. The approach offers a general procedure for eliciting explicit preferences through constructive deliberations among diverse stakeholders.
[Show abstract][Hide abstract] ABSTRACT: Meta-analysis has been an integral tool for fisheries researchers since the late 1990s. However, there remain few guidelines for the design, implementation or interpretation of meta-analyses in the field of fisheries. Here, we provide the necessary background for readers, authors and reviewers, including a brief history of the use of meta-analysis in fisheries, an overview of common model types and distinctions, and examples of different goals that can be achieved using meta-analysis. We outline the primary challenges in implementing meta-analyses, including difficulties in discriminating between alternative hypotheses that can explain the data with equal plausibility, the importance of validating results using multiple lines of evidence, the trade-off between complexity and sample size and problems associated with the use of model output. For each of these challenges, we also provide suggestions, such as the use of propensity scores for dealing with selection bias and the use of covariates to control for confounding effects. These challenges are then illustrated with examples from diverse subfields of fisheries, including (i) the analysis of the stock–recruit relationship, (ii) fisheries management, rebuilding and population viability, (iii) habitat-specific vital rates, (iv) life-history theory and (v) the evaluation of marine reserves. We conclude with our reasons for believing that meta-analysis will continue to grow in importance for these and many other research goals in fisheries science and argue that standards of practice are therefore essential.
Full-text · Article · Oct 2013 · Fish and Fisheries
[Show abstract][Hide abstract] ABSTRACT: Borne out of a collective movement towards ecosystem-based management (EBM), multispecies and multi-sector scientific assessments of the ocean are emerging around the world. In the USA, integrated ecosystem assessments (IEAs) were formally defined 5 years ago to serve as a scientific foundation for marine EBM. As outlined by the US National Oceanic Atmospheric Administration in 2008, an IEA is a cyclical process consisting of setting goals and targets, defining indicators, analysing status, trends, and risk, and evaluating alternative potential future management and environmental scenarios to enhance information needed for effective EBM. These steps should be hierarchical, iterative, non-prescriptive about technical implementation, and adaptable to existing information for any ecosystem. Despite these strengths and some initial successes, IEAs and EBM have yet to be fully realized in the USA. We propose eight tenets that can be adopted by scientists, policy-makers, and managers to enhance the use of IEAs in implementing EBM. These tenets include (i) engage with stakeholders, managers, and policy-makers early, often, and continually; (ii) conduct rigorous human dimensions research; (iii) recognize the importance of transparently selecting indicators; (iv) set ecosystem targets to create a system of EBM accountability; (v) establish a formal mechanism(s) for the review of IEA science; (vi) serve current management needs, but not at the expense of more integrative ocean management; (vii) provide a venue for EBM decision-making that takes full advantage of IEA products; and (viii) embrace realistic expectations about IEA science and its implementation. These tenets are framed in a way that builds on domestic and international experiences with ocean management. With patience, persistence, political will, funding, and augmented capacity, IEAs will provide a general approach for allowing progressive science to lead conventional ocean management to new waters.
Full-text · Article · Jun 2013 · ICES Journal of Marine Science
[Show abstract][Hide abstract] ABSTRACT: Mean trophic level (MTL) is one of the most widely used indicators of marine ecosystem health. It usually represents the relative abundance of fished species across a spectrum of TLs. The reality, ubiquity, and causes of a general decline in the MTL of fisheries catch through time, and whether fisheries catch tracks ecosystem level changes, have engendered much attention. However, the consequences of such patterns for broader ecosystem structure and function remain virtually unexplored. Along the Pacific U.S. Coast, previous work has documented fluctuations and a slow increase in ecosystem MTL from 1977 to 2004. Here, we document a decline in the ecosystem MTL of groundfishes in the same ecosystem from 2003 to 2011, the proximate cause of which was a decrease in the biomass of higher TL groundfishes. Using a food web model, we illustrate how these shifts in ecosystem structure may have resulted in short term, positive responses by many lower TL species in the broader ecosystem. In the longer term, the model predicts that initial patterns of prey release may be tempered in part by lagged responses of other higher TL species, such as salmon and seabirds. Although ecosystem functions related to specific groups like piscivores (excluding high-TL groundfishes) changed, aggregate ecosystem functions altered little following the initial reorganization of biomass, probably due to functional redundancy within the predator guild. Efforts to manage and conserve marine ecosystems will benefit from a fuller consideration of the information content contained within, and implied by, fisheries-independent TL indicators.
[Show abstract][Hide abstract] ABSTRACT: The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.
[Show abstract][Hide abstract] ABSTRACT: Background/Question/Methods
The ocean plays a critical role in supporting human well-being, from providing food, livelihoods, and recreational opportunities to regulating global climate. Sustainable management of the ocean aimed at maintaining the flow of a broad range of services requires a comprehensive and quantitative method to measure the health of coupled human-ocean systems. We created an Ocean Health Index comprising ten diverse goals for a healthy ocean in an effort to standardize assessments and to facilitate comparisons across locations and through time. We illustrate how to apply our framework by calculating the Index for every coastal country on the planet.
This global application illustrates the ability of the Ocean Health Index to (1) represent a portfolio of social benefits, such that there are multiple ways to achieve a single ocean health score, and (2) combine information about the current and near-term future state of ocean health in order to operationalize the concept of sustainability. I will highlight key areas where strategic investment could be used to improve ocean health and how and why prioritizing different actions could improve ocean health scores. The Index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.
[Show abstract][Hide abstract] ABSTRACT: The benefits provided by a healthy ocean are receiving increasing attention in policy and management spheres. A fundamental challenge with assessing ocean health and ecosystem services is that we lack a scientific framework for expressing ecosystem conditions quantitatively in relation to management goals. Here we outline and operationalize a conceptual framework for identifying meaningful reference points and quantifying the current ecosystem state relative to them. The framework requires clear articulation of management goals and is built on a review of current scientific understanding and assessment of data availability. It develops a structured approach for choosing among three classes of reference points, including: (1) functional relationships that establish the ocean state that can be produced and sustained under different environmental conditions, (2) time series approaches that compare current to previous capacities to obtain a particular ocean state in a specific location, and (3) spatial reference points that compare current capacities to achieve a desired ocean state across regional (or, if necessary, global) scales. We illustrate this general framework through the lens of ocean health defined in terms of a coupled social-ecological system, with examples from fisheries, marine livelihoods, and water quality in the USA. Assessment of ocean health and ecosystem services can be significantly influenced by the choice of indicators used to track changes in a management goal, the type of reference point selected, and how one measures the distance of the current state from the reference point. This framework provides flexible, standardized methods for evaluating ocean health and ecosystem services that can advance important components of ecosystem-based management, including marine spatial planning, ecosystem service valuation, and integrated ecosystem assessments.
[Show abstract][Hide abstract] ABSTRACT: Is the health of the ocean good or bad, getting better or getting worse? The answer to this question depends on where it is now relative to where we want it to be. For each of 10 core goals, the Ocean Health Index has established targets, or points of reference that explain where we want ocean health to be. The targets make it possible to track progress toward recovery in less healthy places and celebrate successes in others. We have defined what is to be achieved for the core goals in the Ocean Health Index one at a time—so the targets are selfish. This design causes necessary trade-offs to emerge because what is good for achieving a target for one core goal might not be so good for another. The targets fall into two broad categories. One measures current status compared to the best possible value, where the best possible value either has deep theoretical underpinnings or is based on comparison to a regional maximum. The other type of target measures current ocean condition relative to where it has been during a previous time period. We illustrate these alternative types of targets with real-world examples related to fisheries, marine livelihoods, and water quality, and review how targets have been applied in the global assessment. Ocean health targets clarify exactly what a healthy ocean looks like, which is as essential to the development of a scientifically rigorous Ocean Health Index as it is for communicating about ocean health with policymakers and the public.
[Show abstract][Hide abstract] ABSTRACT: The emerging science and policy arena of marine ecosystem-based management is beset with the challenging question of how to assess the urgency of problems influencing different ecosystem components. In this paper, we introduce a synthetic and efficient framework to identify land- or sea-based activities that pose the greatest risk to valued members of marine ecosystems, including mammals, fishes, and invertebrates. Ecosystem-based risk is scored along two axes of information: the exposure of a population to an activity, and the sensitivity of the population to that activity, given a particular level of exposure. Risk is illustrated in a variety of ways, including two-dimensional contour plots and maps showing regional variation in risk. We apply this risk assessment framework to regional populations of indicator species in Puget Sound, WA, USA. This case study provides insight into how risk varies for particular activity–species combinations, and, because it is applied to indicator species, it also provides an estimate of how different activities influence risk to overall ecosystem structure and function. More generally, the risk assessment approach highlights the linkages between land-based activities and risk to marine species and can be used to evaluate the potential impacts of a diversity of human activities on coastal oceans. The framework is scalable, transparent, and repeatable and can be used now to facilitate the implementation of ecosystem-based management, including integrated ecosystem assessments and coastal and marine spatial planning.
No preview · Article · Jan 2012 · Biological Conservation