Governance processes for management of living resources are increasingly inclusive and participatory, with more use of integrated risk-based approaches. Progress has been challenged by diverse participants holding different values, evidence rooted in different knowledge systems, and participants placed in adversarial roles. Drawing together developments in risk equivalence, the concept of safe operating space, and viability theory, Risk Equivalent Safe Operating Spaces address these challenges. Within the framework diverse perspectives can express their desired ecological, economic, and social outcomes using their own values and indicators. The aggregate suite of all indicators delineates a multidimensional space within which each perspective can describe their relative risk tolerances along each axis, using evidence from all relevant knowledge systems. The “present state” of the socio-ecological system is identified within this space, along with zones of equivalent risk for each perspective, and (if it exists) a zone of Safe Operating Space (SOS) within some acceptable risk tolerance for all perspectives. Pathways can be developed that first seek equivalent risk for all perspectives, then lead towards the center of the common, shared SOS. Where certain perspectives or dimensions of the multidimensional space have explicit priority, the pathways can prioritize minimizing these risks.

Fish biomass is the most widely used indicator of fish stock health. Stocks whose biomass is or has previously collapsed owing to overfishing, and the management systems built around them, may carry a memory of decline, even if biomass has recovered. This is because stock biomass as the main indicator of stock health does not represent all aspects of stock health and biomass can possibly become a weaker indicator of health after stock collapse. These latent weaknesses have been termed “ghosts of overfishing past”. Not accounting for ghosts can impact the speed of stock recovery and susceptibility to further collapses. This concept has been popularised by Professors Jeff Hutchings, Anna Kuparinen, and others. Ghosts are varied and can include changes in vital rates, phenotypic response, fish behaviour, and aspects of the human system such as institutional inertia, fisheries subsidies and income portfolios. The presence of ghosts has implications for fisheries management: altering stock biomass objectives (dynamic reference points) may be appropriate for populations that have experienced collapse even if biomass has recovered. Ghosts should be considered when developing management strategies for populations that have previously experienced large declines.

Ensuring that harvest strategies are robust to climate change is a top priority for many fisheries jurisdictions globally. This is because climate change is altering ecosystem structure and the productivity of marine species. We outline a range of approaches for incorporating climate change impacts within harvest strategies, including how a harvest strategy is specified and changes to monitoring requirements. Approaches evaluated include the use of extended stock assessments, multi-species and ecosystem models, revised management reference points, implementing regime shifts in model parameters, the provision of climate-sensitive catch advice, projections under alternative climate change scenarios and expanded use of management strategy evaluation. We evaluate the utility of these approaches against cost, data needs and uncertainty criteria; highlight key learnings from a range of global jurisdictions and demonstrate the broad array of options available outside of direct incorporation of climate variables within stock assessments. We identify approaches that have been successfully implemented and show that the most complex responses are not always the most successful. While there is no one-size-fits-all way to incorporate climate change within harvest strategies, we outline the need for flexible management arrangements. We also provide examples of approaches that have been successfully implemented, demonstrating that many of the most data-intensive responses will only be applicable in a few cases, necessitating the application of cheaper, less data-intensive approaches that are associated with greater uncertainty.

Open data that can be easily incorporated into analyses are essential for developing ecosystem approaches to marine ecological management: a common goal in fisheries policy in many countries. Although it is not always clear what constitutes an ecosystem approach, it always involves scientists working with a large variety of data and information, including data from physical and oceanographic sampling, multispecies surveys, and other sources describing human pressures. This can be problematic for analysts because these data, even when available, are often held in disparate datasets that do not necessarily correspond at appropriate temporal and spatial scales. Data can often only be obtained by specific requests to individuals in governmental agencies who are delivering on an increasing number of data requests as interest grows in practical ecosystem approach implementation. This data access model is not sustainable and hinders the momentum for ecosystem approach development. We describe a data bundling R package that makes data and climate projections available at appropriate scales to facilitate development of an ecosystem approach for the Gulf of St. Lawrence, Canada. This approach integrates closely with the present workflow of most government analysts, academics in fisheries, and scientists in private industry. The approach conforms with open data initiatives and makes data easily available globally while relieving some of the burden of data provision that can fall to some individuals in government laboratories. The structure and approach are generic, adaptable, and transferable to other regions and jurisdictions.

Fish populations are dynamic; their productivity depends on the environment, predator and prey interactions, and fisheries harvest rates. Failure to account for these factors in fisheries science and management can lead to a misestimation of stock dynamics and productivity, resulting in overexploitation or forgone fisheries yield. Using an online survey, we asked fisheries scientists, industry stakeholders, Indigenous partners, and non-governmental organizations whether changing ecosystem productivity was a problem in their experience, how often dynamic approaches to fisheries reference points have been adopted, what methods had been used, and what fisheries they had been applied to. Changing fisheries or ecosystem productivity was reported as an issue by 96% of respondents; however, 74% of respondents said they had never seen dynamic reference points implemented, 16% said in very few instances, while 10% said frequently. The most common barriers to implementation of dynamic approaches in fisheries management were institutional inertia and uncertainty about whether a change in productivity was lasting. We discuss trade-offs between fisheries management performance and stability.

A changing climate makes the evaluation of human impacts on natural systems increasingly uncertain and affects the risk associated with management decisions. This influences both the achievability and meaning of marine conservation and resource management objectives. A risk-based framework that includes a risk equivalence approach in the evaluation of the potential consequences from human activity, can be a powerful tool for timely and consistent handling of environmental considerations in management advice. Risk equivalence permits a formal treatment of all sources of uncertainty, such that objectives-based management decisions can be maintained within acceptable risk levels and deliver outcomes consistent with expectations. There are two pathways to risk equivalence that can be used to account for the short-term and longer-term impacts of a changing environment: adjusting the degree of exposure to human pressure and adjusting the reference levels used to measure the risk. The first uses existing data and knowledge to derive risk conditioning factors applied to condition management advice on environmental departures from baseline conditions. The second is used to formalise the review and update of management objectives, reference levels and risk tolerances, so they remain consistent with potential consequences from human activity under new biological, ecological and socio-economic realities. A risk equivalence approach is about adapting existing practice to frame environmental considerations within objectives-based risk frameworks, systematically exploring alternative scenarios and assumptions, and conditioning management advice on environmental status. It is applicable to the management of all human activities impacting biological and ecological systems. Concepts of risk, risk conditioning factors, and incremental changes in risk, provide a common currency for the inclusion and communication of environmental effects into advice. Risk equivalence can ensure timely delivery of robust management advice accounting for demonstrated, anticipated or projected environmental effects. This can guide management decisions in a changing world, and greatly facilitate the implementation of an ecosystem approach for the management of human activities.

Redfish ( Sebastes spp.) in the Northwest Atlantic (NWA) extend from Baffin Island in the north to the Gulf of Maine in the south. The two most abundant species are Sebastes mentella and Sebastes fasciatus, which are morphometrically similar and difficult to visually distinguish. Redfish are long-lived, slow-growing, late-maturing, tend to produce large year classes episodically, and have complex population structure. Intraspecific genetic groups are abundant in the NWA. They are often semipelagic and patchily distributed, which makes them difficult to survey. These are all characteristics that cause difficulties for stock assessment and for sustainable fisheries management. This was the focus of The Ocean Frontier Institute Northwest Atlantic Redfish Symposium in 2018. In this paper, we synthesize the information known about NWA redfish. To improve the scientific basis for sustainable harvest strategies, key research recommendations involve (1) improved biological sampling including species and ecotype; (2) developing integrated stock assessment models; (3) developing harvest strategies with management reference points that are appropriate for redfish; (4) improving fishing technology and practices to avoid capture of small nonmarketable redfish and other species.

There is increasing demand within fisheries management for the adoption of management approaches that incorporate in-depth stakeholder participation, scientific uncertainty, multiple objectives, and characterizations of risk. One such approach—management strategy evaluation (MSE)—relies on participation with fishery interest groups to consolidate knowledge of the fishery system, define goals, and evaluate feasible management options. However, the focus of much of the literature on MSE emphasizes steps in implementation and its practical application, despite the fact that technical aspects of MSE have the potential to alienate participants without MSE experience. Using the Units 1 and 2 Canadian Atlantic redfish fishery as a case study, we here describe lessons learned from the MSE developed for this rebuilding fishery, focusing on four key challenges: identifying participants for MSE processes; clearly defining their roles; educating participants on the purpose, benefits, and scope of MSE; and mediating disagreements to acquire critical cooperation, inputs, and feedback from the different stakeholder groups within the MSE process.

The rate of climate change (CC) has accelerated to the point where it now affects the mid- to long-term sustainability of fishing strategies. Therefore, it is important to consider practical and effective ways to incorporate CC into fisheries advice so that the advice can be considered conditioned to CC. We developed a model to characterise the empirical relationship between a variable affected by climate and fish production. We then used model projections as a foundation for a risk analysis of CC effects on harvesting of Greenland halibut Reinhardtius hippoglossoides in the Gulf of St Lawrence, Canada. The risk-based approach quantified a) the relative change in risk of a status quo fishing strategy under various CC scenarios, and b) the change in fishery exploitation rates required to achieve a management objective over a specified time period at a level of risk considered acceptable (risk equivalent fishery exploitation advice). This empirical approach can be used to develop risk-based advice for any other external variable that affects stock production in addition to climate-related variables and it can be applied in most situations where there is an index of stock biomass and fisheries catch. Shifting the focus from process-based understanding of the responses of fish stocks to CC to quantification of how CC-contributed uncertainty can alter the risks associated with different fishing strategies and/or management options, can ensure timely delivery of robust scientific advice for fisheries under non-stationary environmental conditions.

Recruitment in age-structured stock assessment models can be forecasted using a variety of algorithms to provide advice on the anticipated consequences of different possible management actions. Selecting one method over another usually involves some subjectivity, yet can be consequential to the provision of advice. Extensive case-specific testing is not always feasible. We evaluated the forecast skill in 3-, 5- and 10-year forecasts of 16 recruitment forecasting methods under various circumstances to provide a broad evaluation and general guidelines on the reliability of forecasts. We used 31 operating models based on existing stock assessment models applied to a diversity of stocks with empirical data, which we show to be generally representative of assessed stocks worldwide. Although no single best-performing method could be identified, we found that time-series methods were most likely to perform poorly. Both forecast skill across all methods and forecast sensitivity to the selected method were linked to the properties of the stock or assessment: age at maturity and recruitment autocorrelation in 3-year forecasts and previous long-term recruitment variability in 10-year forecasts. In some situations, all forecasting methods resulted in systematic over- or underestimation of spawning stock biomass. The simulation approach employed here to assess forecast performance, rooted directly in the predictions of existing stock assessment models, can be a complementary tool to existing simulation approaches which generate alternative sets of population dynamics or observations and we discussed the advantages and limitations.

The expansion of the aquaculture industry in the last several decades has raised concerns about potential ecological impacts of the industry. Bivalve culture, particularly mussel farming, relies on naturally occurring plankton and numerous studies have demonstrated top-down control on phytoplankton, increased nutrients through excretion of metabolic wastes and remineralization of faeces and pseudofaeces, and bottom-up effects on predators and scavengers through mussel fall-off. However, results are inconsistent between studies, and hydrodynamic conditions and nutrient availability are thought to play an important role in the magnitude and the direction of the ecological effects of mussel culture on the surrounding ecosystem. We used qualitative network models (QNMs), to outline a general model that integrates these environmental conditions and (1) evaluated the ability of different model configurations to reproduce known responses to perturbations, (2) analyzed the behaviour of key components to contrasting hydrodynamic and nutrient condition scenarios, and (3) identified the most influential features of the derived scenarios. The model that included uncertain linkages to characterize unknown relationships performed best based on predetermined validation criteria; the addition of semi-quantitative information on the relative strength of certain linkages improved accuracy and sign determinacy of outcomes. The presence of suspended mussel culture negatively affected primary producers, zooplankton and deposit-feeders, and had a positive effect on predators and scavengers, especially in low-energy environments. Hydrodynamic conditions were shown to have a major impact on the response of the community to mussel culture, while nutrient availability had a very minor impact.

Aim Previous analyses of marine fish species richness based on presence‐absence data have shown changes with latitude and average species size, but little is known about the underlying processes. To elucidate these processes we use metabolic, neutral and descriptive statistical models to analyse how richness responds to maximum species length, fish abundance, temperature, primary production, depth, latitude and longitude, while accounting for differences in species catchability, sampling effort and mesh size. Data Results from 53,382 bottom trawl hauls representing 50 fish assemblages. Location The northern Atlantic from Nova Scotia to Guinea. Time period 1977–2013. Methods A descriptive generalized additive model was used to identify functional relationships between species richness and potential drivers, after which nonlinear estimation techniques were used to parameterize: (a) a ‘best’ fitting model of species richness built on the functional relationships, (b) an environmental model based on latitude, longitude and depth, and mechanistic models based on (c) metabolic and (d) neutral theory. Results In the ‘best’ model the number of species observed is a lognormal function of maximum species length. It increases significantly with temperature, primary production, sampling effort, and abundance, and declines with depth and, for small species, with the mesh size in the trawl. The ‘best’ model explains close to 90% of the deviance and the neutral, metabolic and environmental models 89%. In all four models, maximum species length and either temperature or latitude account for more than half of the deviance explained. Main conclusions The two mechanistic models explain the patterns in demersal fish species richness in the northern Atlantic almost equally well. A better understanding of the underlying drivers is likely to require development of dynamic mechanistic models of richness and size evolution, fit not only to extant distributions, but also to historical environmental conditions and to past speciation and extinction rates.

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There exist few recommendations for managing stocks with spasmodic recruitment, despite such stocks being not uncommon. Management procedures (MPs), developed for two species of redfish (Sebastes mentella and Sebastes fasciatus) in eastern Canada, are recommended for setting catch limits during periods of high and low abundance. A well-designed fishery-independent trawl survey is essential to provide advance warning of strong recruitment events and project future recruitment. Under an “inventory management” strategy, a more appropriate aim in spasmodic stocks may be to maximize the number of years with “good catches,” instead of maximizing total catches, as is traditionally considered in management strategy evaluation (MSE). Following a spasmodic recruitment event, an empirical harvest control rule based on larger fish delays the harvest of large cohorts by a few years, targets more commercially valuable fish sizes, and reduces the risk of growth overfishing. Capped MPs produced longer periods of large catches than uncapped MPs. MPs allowed for low harvests during periods of low abundance, thus avoiding unnecessary hardship in the industry. MPs evaluated here could be good candidates for other stocks with similar or less extreme recruitment variability.

The northern spawning contingent of Western Atlantic mackerel is currently at low biomass and catches are largely underestimated. Catch statistics for Canada are incomplete, and the amount of northern contingent fish caught in the US mackerel fishery is unclear. Our goal was to assess the impact of missing catch on quota management effectiveness and to provide advice for stock rebuilding in the face of large catch uncertainty. As part of a management strategy evaluation (MSE), we assessed how simple harvest control rules (HCRs) performed under different assumptions of catch uncertainty. Results showed that, at present low biomass levels, reducing missing catch was generally more important than the choice among certain HCRs. Canadian undeclared catch would need to be reduced markedly to achieve even short-term rebuilding objectives. To reach long-term rebuilding objectives, the proportion of northern contingent fish caught in the US fishery would also need to be accounted for. We demonstated how an MSE can help inform all involved parties of the trade-off between missing catch and quota magnitude and effectiveness, and provided directions for future developments in management and science.

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The true spatiotemporal structure of a fish population is often more complex than represented in assessments because movement between spawning components is disregarded and data at the necessary scale are unavailable. This can generate poor advice. We explore the impacts of modelling choices and their associated risks given limited data and lack of biological knowledge on spawning component structure and connectivity. Pseudo-data for an age structured fish population were simulated with two spawning components that experience various levels of connectivity and that might overlap during a certain period but segregate during reproduction. A variety of implicit spatiotemporal and simpler models were fitted to the pseudo-datasets, mimicking different situations of data availability. To reproduce the true stock characteristics, the spatiotemporal models required total catch data disaggregated by spawning component; however, catch-at-age was not as important nor were disaggregated biomass indices to reproduce true dynamics. Even with just 5% connectivity between spawning components, both the spatiotemporal models and simpler alternatives generally overestimated stock biomass. Although bias was smallest when considering one unit population, spawning components might still need to be considered for management and conservation. In such case, the spatiotemporal model was less influenced by ignored connectivity patterns compared to a model focussing on one spawning component only.

A series of interviews with Canadian redfish Sebastes spp. fishing industry participants active in the 1980s and 1990s was conducted to determine how fish were caught, how much was caught (reported landings, unreported landings, and discards), and the sizes of fish caught during that time. Indicators of total fish catch derived from these interviews showed that reported catch may have underestimated catch by a factor of 2 or more. The proportion of small fish landed may also have been underestimated by a factor of 150-200. The re-examination of catches from interviews with fishermen can provide a useful context for interpreting population model abundance estimates for this stock. This interpretation can have implications for present-day stock assessment and fishery advice.

The interspecific abundance-occupancy relationship (AOR) is a widely used tool that describes patterns of habitat utilization and, when evaluated over time, may be used to identify large-scale changes in community structure. Our primary goal for this research was to validate the utility of AORs as temporal indicators of community state. We used long-term survey data in four regions of the northwest Atlantic coastal shelf (NWACS) to estimate the diversity of spatial behaviors in each community, which we modeled with negative binomial (NB) distributions. NB parameters were used to generate time series data for simulated communities, from which AORs were then estimated and evaluated for temporal trends. We found that AORs from simulated communities were similar in year-to-year variation to empirical relationships. In order to further understand the role of spatial diversity in the generation of AOR trends, we did additional simulations where NB parameters were manually manipulated. In one instance, we ran simulations while holding species' parameters constant over time. This treatment effectively removed trends, suggesting that temporal change in community relationships was the result of genuine variation in intraspecific spatial use. In another set of simulations, we conducted a case study to evaluate the impact of a select group of schooling and spatially aggregating species on an especially rapid shift in AORs in the Gulf of Maine from 1973 to 1983. Removals of these species reduced the magnitudes of most trends, demonstrating their importance to observed community changes. This research directly links variation in AORs to distribution and density-related processes and provides a potentially powerful framework to identify community-level change and to test ecological and mechanistic hypotheses.

Fish stock assessments routinely integrate catch data. Misreported catches, however, can lead to biased estimates of stock size, production, reference points and poor advice on stock exploitation. Canadian Atlantic mackerel (Scomber scombrus) landings are thought to be significantly underestimated because this stock is subject to large bait and recreational fisheries that are not required to report catches. As this might lead to stock size underestimation, we developed a state-space age-structured model that accounts for catch data uncertainties using a censored catch method, which involves data on lower and upper catch limits. We explored how censoring influences parameter estimates and six common reference points, and their sensitivity to the choice of an upper catch limit. Modelling catch as a censored random variable led to more realistic estimation of state variables such as a higher estimate of SSB. The relationship between reference points and the range of possible catches was not straightforward, but F0.1, Fmax and F40% were more stable than SSBmsy, Fmsy and Fmed. Applying the censored catch approach to Canadian Atlantic mackerel highlighted the importance of informing the upper catch limit when faced with other sources of uncertainty and showed that it was crucial to provide realistic management advice.