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Contrast between 3 NSMAP strategies with safeguard using Realistic HCR type 4 (see Fig 4) and fishing at F msy by 2020 in each. Strict no discards (red and left bar/box in each pane), discard avoidance (green and middle bar/box), discard continues (blue and right bar/box). The solid black
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The possible impacts of the European Commission’s proposed North Sea Multi-Annual Plan are evaluated in terms of its likely outcomes to achieve management objectives for fishing pressure, species’ biomass, fishery yield, the landed value of key species and ecosystem objectives. The method applies management strategy evaluation procedures that emplo...
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Citations
... How are EwE Models informing the issue? EwE models are being used to evaluate the sustainability of mixed-species fisheries in the North Sea (Heymans et al., 2011;Mackinson et al., 2009Mackinson et al., , 2018Stäbler et al., 2016Stäbler et al., , 2019 and off the west coast of Scotland (Alexander et al., 2015;Baudron et al., 2019). Similar to other north temperature ecosystems Lucey et al., 2012;Mueter & Megrey, 2006), the general conclusion from these models is that simultaneously achieving MSY from single-species stock assessments for all species in a mixed-species fishery is not possible due to Significant effort reductions (i.e., 20%-50%) may be required for some fleets in order to achieve sustainable harvest rates for all species (Mackinson et al., 2009;Stäbler et al., 2019). ...
... However, linked EwE and species distribution models suggest more significant positive and negative effects of limiting discards that differ across species (Pennino et al., 2020). Whether the LO has net positive or negative effects may also differ between fisheries that are regulated by effort controls compared to those regulated by catch limits due to different incentives for selective harvesting (Celić et al., 2018;Mackinson et al., 2018). EwE models also suggest the effects of the LO will depend on the status of the relevant populations, with overfished species benefiting more from reductions in fishing effort than in discarding, whereas limiting discards has greater effects for species where landed catch is near sustainable levels Moutopoulos et al., 2018). ...
... EwE models also suggest the effects of the LO will depend on the status of the relevant populations, with overfished species benefiting more from reductions in fishing effort than in discarding, whereas limiting discards has greater effects for species where landed catch is near sustainable levels Moutopoulos et al., 2018). A general result that has emerged from EwE models of multiple ecosystems is the potential negative effects of limiting discards on scavenger populations, particularly marine birds but also marine mammals and sea turtles, that have come to rely on discards as a food resource (Celić et al., 2018;Fondo et al., 2015;Mackinson et al., 2018;Moutopoulos et al., 2018). ...
The implementation of ecosystem management requires ecosystem modelling within the context of a natural resource management process. Ecopath with Ecosim (EwE) is the most widely used modelling platform for investigating the dynamics of marine ecosystems, but has played a limited role in fisheries management and in multi‐sector resource decision‐making. We review 10 case studies that demonstrate the use of EwE to support operational resource management. EwE models are being used to inform tactical decision‐making in fisheries and other ocean use sectors, as well as to identify key trade‐offs, develop appropriate policy objectives, and reconcile conflicting legislative mandates in a variety of ecosystems. We suggest the following criteria to enhance the use of EwE and other ecosystem models in operational resource management: (1) a clear management objective that can be addressed through modelling; (2) an important trade‐off and a receptive policy context amenable to trade‐off evaluation; (3) an accessible and well‐documented model that follows best practices; (4) early and iterative engagement among scientists, stakeholders, and managers; (5) integration within a collaborative management process; (6) a multi‐model approach; and (7) a rigorous review process. Our review suggests that existing management frameworks are as much or more of a limitation to the operational use of EwE than technical issues related to data availability and model uncertainty. Ecosystem models are increasingly needed to facilitate more effective and transparent decision‐making. We assert that the requisite conditions currently exist for enhanced strategic and tactical use of EwE to support fisheries and natural resource management.
... One way this can be done is through management strategy evaluations (MSE), where multispecies models can be used as the operating model (e.g. Grüss et al., 2016;Mackinson et al., 2018;Kaplan et al., 2021;Pérez-Rodríguez et al., 2022) and can provide a strategic evaluation of the long-term consequences of alternative management actions across a suite of species. However, we note that projections of multispecies models can be useful in revealing tradeoffs associated with particular policy choices or sets of expectations about reference points (e.g. stock size or goals for other species) on their own, without having to be connected to a feedback management control mechanism as done within an MSE. ...
Multispecies models have existed in a fisheries context since at least the 1970s, but despite much exploration, advancement, and consideration of multispecies models, there remain limited examples of their operational use in fishery management. Given that species and fleet interactions are inherently multispecies problems and the push towards ecosystem-based fisheries management, the lack of more regular operational use is both surprising and compelling. We identify impediments hampering the regular operational use of multispecies models and provide recommendations to address those impediments. These recommendations are: (1) engage stakeholders and managers early and often; (2) improve messaging and communication about the various uses of multispecies models; (3) move forward with multispecies management under current authorities while exploring more inclusive governance structures and flexible decision-making frameworks for handling tradeoffs; (4) evaluate when a multispecies modelling approach may be more appropriate; (5) tailor the multispecies model to a clearly defined purpose; (6) develop interdisciplinary solutions to promoting multispecies model applications; (7) make guidelines available for multispecies model review and application; and (8) ensure code and models are well documented and reproducible. These recommendations draw from a global assemblage of subject matter experts who participated in a workshop entitled “Multispecies Modeling Applications in Fisheries Management”.
... The North Sea ecosystem has been extensively studied and there are several extant ecosystem models of the region. For the quantitative analysis, we chose to use two end-to-end ecosystem models built using the Ecopath with Ecosim (EwE) modelling framework, one for the Kattegat (ICES, 2019) and another for the North Sea (Mackinson et al., 2018). Similar scenarios for future human activities were run using both the FCMs and EwE models, and model results were compared based on the responses to individual model components as well as multivariate forcing. ...
... In addition to modelling the predatory mortality between groups, the impact of 11 fishing fleets that represent the major international fleets operating in the North Sea was considered, with functional groups and fishing fleets interconnected through 1521 links [Supplementary Figure S5A and Table 1 ( Mackinson et al., 2018)]. ...
... tics also further elucidate the understanding of key ecosystem processes that might otherwise be overlooked by proceeding to the dynamic phase of food-web modelling without pausing to rigorously evaluate these diagnostics (Link, 2010). The North Sea model was also approved by ICES (2016b) as a "key-run" and uncertainty was investigated by Mackinson et al. (2018). As presented by Uusitalo et al. (2022) for the central Baltic Sea EwE model (Bauer et al., 2018), a Monte Carlo approach was used to see if model parametrization varied within reasonable limits. ...
The complexities of ecosystem-based management require stepwise approaches, ideally involving stakeholders, to scope key processes, pressures, and impact in relation to sustainability and management objectives. Use of qualitative methods like Fuzzy Cognitive Mapping (FCM) with a lower skill and data threshold than traditional quantitative models afford opportunity for even untrained stakeholders to evaluate the present and future status of the marine ecosystems under varying impacts. Here, we present the results applying FCM models for subregions of the North Sea. Models for the southern North Sea, Skagerrak, Kattegat, and the Norwegian Trench were developed with varying level of stakeholder involvement. Future scenarios of increased and decreased fishing, and increased seal biomass in the Kattegat, were compared with similar scenarios run on two quantitative ecosystem model. Correspondence in response by the models to the same scenarios was lowest in the southern North Sea, which had the simplest FCM model, and highest in Norwegian Trench. The results show the potential of combining FCM and quantitative modelling approaches in integrated ecosystem assessments (IEAs) and in future ecosystem-based management advice, but to facilitate such comparisons and allow them to complement and enhance our IEAs, it is important that their components are aligned and comparable.
... MSMs also have considerable utility as operating models (OMs) within Management Strategy Evaluation (MSE) frameworks (semianalogous to Operational Management Procedures (OMP) (Rademeyer et al., 2007;Punt et al., 2016;Smith et al., 2017;Kaplan et al., 2021) but this aspect is not discussed in detail in this paper and the reader is referred to examples of multispecies MSEs such as Mackinson et al. (2018), Thorpe and De Oliveira (2019) as well as to Kaplan et al. (2021) who provide a more in-depth review. When used with multispecies models, MSE has been shown to be an effective risk management tool for simulation testing the robustness of harvest control rules to a range of uncertainties, including due to changing climate, economic drivers and trophic interactions (Dichmont et al., 2008;Plagányi et al., 2013;Punt et al., 2014;Ono et al., 2018;ICES, 2019ICES, , 2021. ...
Stock assessment models often assume natural mortality rates (M) are constant and attribute the variability in a stock’s overall mortality rate to variability in fishing mortality and recruitment. However, this assumption may not be valid if M varies due to both direct and indirect trophic interactions as well as environmental variability. This is particularly the case when there are substantial changes in the overlapping abundances of a key predator or prey species, or extreme environmental changes impacting an ecosystem. Hence multispecies models (MSMs) are used to explicitly capture variations in natural mortality rates and improve the ability to discriminate between mortality due to fishing versus natural mortality, plus quantify the influences of fishing on the broader ecosystem, consistent with an ecosystem approach to fishing (EAF). There are a growing number of approaches to modelling natural mortality rates in MSMs, with models developed for tactical applications requiring a higher level of rigour and consideration of uncertainty than broad strategic ecosystem models. We overview approaches to modelling natural mortality in Models of Intermediate Complexity for Ecosystem assessments (MICE) and use four case studies to highlight lessons learnt, applications and provide some guidelines going forward. We identify ten broad application categories for MSMs (incorporating explicit representation of components of M), to advance EAF. These include: (1) quantify variability in natural mortality by age and over time as inputs to single species stock assessment models, because of the recognition that predation mortality (M2) is a large and variable portion of total M; (2) inform ecosystem reference points; (3) use as operating models in Management Strategy Evaluation frameworks; (4) simulation test broader management levers; (5) optimise multispecies harvest strategies; (6) inform on management of bycatch and ‘choke’ species; (7) represent and forward project trajectories and model recovery scenarios for threatened and protected species; (8) correctly attribute sources of mortality to support management efforts; (9) pest management and (10) broader applications (e.g. habitat alterations). Using well-constructed MSMs to correctly specify M reduces bias in model parameters, reference points and projections and is increasingly important as ecosystems respond to a more variable and changing climate.
... Uncertainty within individual ecosystem models has previously been explored (e.g. Thorpe et al. 2015, Spence et al. 2016, Mackinson et al. 2018; however, these attempts are likely to underestimate the uncertainty, as uncertainty across models is often ignored. Management advice should ideally consider the outputs of a suite of models, but combining them is not as easy as averaging over their outputs or ascribing a simple weight to each, as we do not expect the discrepancies of each of the models to be independent (Rougier 2007, Christiansen 2020. ...
... It contains >10 fishing fleets and > 60 functional groups, some of which are split into multiple age stanzas. We used parameter uncertainty from Mackinson et al. (2018). EwE was able to predict ZB, Z:P, BM and TFB from 1991 until 2050. ...
To effectively implement ecosystem-based fisheries management, tools are needed that are capable of exploring the likely consequences of potential management action for the whole ecosystem. Quantitative modelling tools can be used to explore how ecosystems might respond to potential management measures, but no one model can reliably forecast all aspects of future change. To build a robust basis for management advice, a suite of models can be used, but the interpretation of the joint output of multiple models can be difficult. We employ a newly developed ensemble approach to integrate 5 different ecosystem models and estimate changes in ecosystem state within a single probabilistic forecast. We provide evidence on the response of ecosystem state (measured using ecological indicators relating to plankton, fish and top predators) to potential fisheries management scenarios. We demonstrate that if future fishing mortality is consistent with maximum sustainable yield policy, the North Sea fish community will recover in terms of its size structure and species composition. However, there is currently large uncertainty in trends of future fish biomass, plankton and top predators. We conclude that (1) this ensemble approach can be applied directly to policy-relevant questions and add value for decision makers, as multiple aspects of uncertainty are considered; (2) future research should prioritise improvements in model skill via a reduction in uncertainty surrounding biomass estimates; and (3) fisheries management that leads to sustainable fishing levels can be considered appropriate for 2 crucial aspects of fish biodiversity: species composition and size structure.
... Therefore, we included a management component. We used the broken stick harvest control rule that defines a stock's biomass thresholds below which management rules are applied, reducing the effort allowed (Dichmont et al., 2016;Mackinson et al., 2018). While managing a multispecies fishery based on single species criteria that do not consider species and fleet interactions is a limitation, it reflects the current management framework of the Australian Southern and Eastern Scalefish and Shark Fishery as of many other fisheries worldwide (e.g. ...
Ecosystem‐based fisheries management aims to ensure ecologically sustainable fishing while maximising socio‐economic benefits. Achieving this goal for mixed fisheries requires better understanding of the effects of competing fishing fleets on shared resources and economic performance. Proposed management strategies that promote either specialisation or diversification of catches may result in unintended consequences for ecosystem‐based management. Here, we ask: does increased or decreased competition among fleets lead to better ecological and socio‐economic fishery outcomes? How effective are currently proposed management strategies for achieving these outcomes? We integrated fleet dynamics into a multispecies size‐spectrum model and parameterised this model to represent Australian Southern and Eastern Scalefish and Shark Mixed Fishery. We compared the fishery status quo to two extreme scenarios: no competition, where each species is fished only by one fleet (specialisation); and maximal competition, where all fleets catch all species (diversification). To answer our second question, we considered three more plausible scenarios resulting from proposed management strategies: decreased competition due to reduced bycatch, and increased competition due to increased catches of under‐utilised or valuable species. We used indicators to explore scenarios’ outcomes. Our model reproduced observed trends in fishing effort and yield. Extreme scenarios showed that a fishery dependent on single species management structures is more likely to achieve ecosystem‐based management objectives if fleets do not compete, while maximal competition can lead to the fishery collapse as management buffers the ecological impact of diversifying. The more plausible scenarios showed little improvement over the status quo, with mixed ecological and negative economic effects. Synthesis and applications: Our model can be applied to assess mixed fisheries ecosystem‐based management strategies. Our results show that, under single species management approaches, greatest outcomes can be achieved when fleets are specialised, whereas managing fleets that catch similar species is unlikely to be successful. They question the effectiveness of these management approaches in providing resilience for mixed fisheries facing changes and highlight the need to account for fleet interactions in the evaluation of management strategies to avert unintended risks.
... Explicit inclusion of sheries in ecosystem models, combined with the ability to simulate stochastic stock assessment error, as suggested by Rice and Duplisea (2014), renders EwE a promising platform for evaluating ecological impacts of sheries management (Walters et al., 2005), searching for potential EBFM strategies (Marasco et al., 2007;Plagányi, 2007;Chagaris et al., 2020;Howell et al., 2021) and precautionary reference points (Pikitch et al., 2012b;Chagaris et al., 2020), and assessing trade-o s among ecological and socioeconomic management objectives (Buchheister et al., 2017;Kaplan et al., 2013Kaplan et al., , 2017Koehn et al., 2017). Numerous recent studies have utilized ecosystem models built in EwE (Pikitch et al., 2012b;Buchheister et al., 2017;Mackinson et al., 2018), Rpath (the R implementation of EwE; Lucey et al., 2021), Atlantis (Fulton et al., 2014;Kaplan et al., 2020), and OS-MOSE (Grüss et al., 2016) as operating models (OMs) for MSEs or similar analyses deployed in search of EBFM strategies. These studies, often concerned with forage sh (Pikitch et al., 2012b;Buchheister et al., 2017;Kaplan et al., 2020), cast doubt on the recent statement (Kronlund et al., 2018) that ecosystem considerations should not yet be included in Paci c herring OCPs for lack of suitable OMs. ...
... This tool was employed in the global analysis by Pikitch et al. (2012b) and the pilot study by Surma et al. (2018b). However, MSE functionality in EwE has recently been greatly improved by a new plugin developed at the Centre for Environment, Fisheries and Aquaculture Science (Cefas) in the UK (Mackinson et al., 2018). Unlike the older, built-in EwE MSE module, this new tool can simulate complex HCRs (e.g. that used in Southeast Alaska herring sheries; Thynes et al., 2016Thynes et al., , 2019 and account for EwE parameter uncertainty and strategy implementation error through Monte Carlo resampling. ...
... Unlike the older, built-in EwE MSE module, this new tool can simulate complex HCRs (e.g. that used in Southeast Alaska herring sheries; Thynes et al., 2016Thynes et al., , 2019 and account for EwE parameter uncertainty and strategy implementation error through Monte Carlo resampling. While neither the original EwE MSE module nor the Cefas MSE tool provides an MSE of the type recommended for examining potential EBFM strategies by Punt et al. (2016a), as both apply simpli ed representations of stock assessment to the OM, the Cefas MSE tool provides powerful functionality for comparatively evaluating ecosystem impacts of HCRs (Mackinson et al., 2018), which is one of the primary aims of the present study. Thus, we employed the Cefas MSE tool to investigate the e ects of current and proposed management strategies (HCRs) from across the Northeast Paci c on herring biomass, the southeastern Gulf of Alaska ecosystem, and socioeconomic sheries performance. ...
Pacific herring (Clupea pallasii) plays an important and multifaceted role in the Northeast Pacific as a forage fish in coastal ecosystems, target species for commercial fisheries, and culturally significant subsistence resource for coastal communities. This study comparatively evaluated herring fisheries management strategy performance relative to ecological and socioeconomic objectives. Management strategy evaluation employed a mass-balanced ecosystem operating model and accounted for parameter uncertainty, stock assessment error, and strategy implementation error through Monte Carlo resampling. Results revealed a notable trade-off between stable herring catches and high biomasses of herring and several predators. Herring biomass control point values influenced this trade-off more than harvest control rule form. All British Columbia and Alaska strategies yielded similar ecological and socioeconomic impacts relative to the unfished herring baseline. Precautionary strategies recommended for forage fish combined high ecosystem benefits and socioeconomic costs. Reducing fishing mortality fourfold within an existing strategy suggested a possible compromise solution to this trade-off. However, ecological impacts of all strategies were sensitive to operating model parameter uncertainty, stock assessment error, and strategy implementation error, with the potential for undesirable ecosystem states across all strategies. This study suggests trade-offs among management objectives should be considered in pursuing ecosystem-based fisheries management for forage fish.
... However, decisions regarding the best course of action involve weighting different strategies that often produce nonlinear or unanticipated results due to the nature of aquatic ecosystem dynamics. These two management levers' outcomes can be evaluated utilizing the Ecopath with Ecosim (EwE) modeling framework to explore how the approaches would affect marine ecosystems (Mackinson et al. 2018). Here we aim to: (1) develop a habitat reconstruction forcing function using landscape-based historical river biomass time series, (2) test two fishing effort scenarios to evaluate the degree of biomass change in the system when we consider effort reduction of gears directly affecting alosines, and all the gears, and (3) test how the worse performing fishing effort reduction scenario, from the perspective of alosine recovery, is altered with the addition of the habitat reconstruction forcing function. ...
Small pelagics, or forage fish, link lower and higher trophic levels in marine food webs. Recently, attention has been given to the management of forage fish, including anadromous river herring (Alewife Alosa pseudoharengus, blueback herring A. aestivalis) and American shad (A. sapidissima) due to their current depleted status and historically important ecological and economic roles. Little is known about the impact of changes in their biomass on marine food webs and what management practices will promote their recovery. Estimated historical riverine productivity was utilized to evaluate potential ecosystem impacts of the increasing river to ocean connectivity to resemble 19th‐century conditions. The Ecopath with Ecosim modeling framework was used to simulate management strategies, focused on anadromous forage fish, by creating scenarios of fisheries reduction (mixed fishery effort reduction) and river to ocean habitat connectivity (75% of historical connectivity achieved). Sixty‐year simulations covered the entire time series including a 36‐year forecast period to evaluate the ecosystem impacts of management strategies. Results suggest nonlinear relationships and large changes in biomass flows from forage fish to upper trophic levels in the Gulf of Maine ecosystem. Increases in biomass were observed for pelagic sharks, demersal piscivores, and species of conservation concern such as pinnipeds and seabirds, although overall results were strongly influenced by indirect trophic effects. Promoting anadromous forage fish recovery through increased connectivity resulted in the redundancy of marine ecosystem niches that would increase resilience to climate, fisheries, and other perturbations. This study highlights the value of employing ecosystem models for testing management scenarios to contrast different approaches to recover anadromous forage fish towards its former ecological prominence.
... The construction of their North Sea model (Mackinson and Daskalov, 2007), North Sea ICES Key run (ICES, 2016), and evaluation of fisheries management strategies (Platts and Mackinson, 2017;Mackinson et al., 2018) inspired the creation and design of our northern North Sea model. The model of Mackinson and Daskalov (2007) treated the whole North Sea as a single unit, however the oceanographic and biological characteristics of the northern and southern North Sea are distinct. ...
This report outlines the model topology, describing in detail the methods used to create an ecologically balanced Ecopath model of the northern North Sea. This model builds upon previous research by Dr Steven Mackinson and others at the Centre for Environment Fisheries and Aquaculture Science (Cefas). The construction of their North Sea model (Mackinson and Daskalov, 2007), North Sea ICES Key run (ICES, 2016), and evaluation of fisheries management strategies (Platts and Mackinson, 2017; Mackinson et al., 2018) inspired the creation and design of our northern North Sea model.
It is hoped that this northern North Sea ecosystem model can be used to test future fisheries management scenarios of relevance to both Shetland and the wider Scottish and UK fishing industry.
... For instance, Punt et al. (2001) ran MSE simulations to evaluate management strategies for species in the South East Fishery of Australia, and broadly represented biological interactions with an error term applied on the natural mortality within the population dynamics component of the OM. While such methods are advantageous to extend MSE simulations under a single-species context, using OMs that explicitly handle the biological interactions of the resource allows for more informed assessments of the direct and indirect effects between the resource, fishery and ecosystem (Mackinson et al. 2018). Because of this, conducting MSE simulations with more complex models is considered an essential Punt et al. 2016a). ...
... To support impact assessments of EU proposals for a multiannual plan covering the demersal fisheries in the North Sea, quantitative evaluations were presented by the Expert Working Group of the STECF (STECF 2015) and Mackinson et al. (2018). The STECF ( (St€ abler et al. 2014(St€ abler et al. , 2016ICES 2016c). ...
... Because the MSE plug-in did not have an explicit monitoring sub-model at that time, a monitoring model was approximated by applying observational error to the average biomass of each assessed group predicted by the OM over the previous twelve months in the simulation. Moreover, it was not practical to simulate complex assessments for multiple groups with the MSE plug-in yet, so stock assessments were modeled by computing a weighted average of the "survey biomass" (Walters 2004;Mackinson et al. 2018). Scenarios simulated by STECF (2015) included variations of HCR structural form, low and high F reference points, and the use of "safeguards" (i.e., reduction of fishing pressure if the stock status dropped below a threshold-similar to the constant escapement HCR). ...
Management Strategy Evaluation (MSE) is a framework to explore the tradeoffs amongst fishing strategies and assess the consequences for achieving management goals provided sources of uncertainty by means of simulation models (referred to as operating models). Single-species stock assessment often implements simulations for MSE, but the operating models often omit the dynamics of key biological interactions. This could be a disadvantage for the evaluation of tradeoffs as species interactions could have an impact on the performance of harvesting strategies. Tools for conducting ecosystem-based fisheries management (EBFM), such as integrated ecosystem assessments, include executing MSEs with ecosystem models, many of which explicitly include biological interactions. Although the support for EBFM has grown over the years, the amount of information provided by MSEs based on ecosystem models appears to be limited. A clear summary of such efforts would provide beneficial information for future efforts for EBFM. Herein, an inventory of applications simulating MSEs with ecosystem models that explicitly include biological interactions was developed based on findings from a literature review. First, the methodologies and foci across all identified applications are analyzed. Next, summaries of each application are provided. Lastly, general observations are provided along with recommendations for future applications.
