Management Strategy Evaluation Research Articles

Species Home-Making in Ecosystems: Toward Place-Based Ecological Metrics of Belonging

Globalization has undeniably impacted the Earth’s ecosystems, but it has also influenced how we think about natural systems. Three fourths of the world’s forests are now altered by human activity, which challenges our concepts of native ecosystems. The dichotomies of pristine vs. disturbed as well as our view of native and non-native species, have blurred; allowing us to acknowledge new paradigms about how humans and nature interact. We now understand that the use of militaristic language to define the perceived role of a plant species is holding us back from the fact that novel systems (new combinations of all species) can often provide valuable ecosystem services (i.e., water, carbon, nutrients, cultural, and recreation) for creatures (including humans). In reality, ecosystems exist in a gradient from native to intensely managed – and “non-nativeness” is not always a sign of a species having negative effects. In fact, there are many contemporary examples of non-native species providing critical habitat for endangered species or preventing erosion in human-disturbed watersheds. For example, of the 8,000–10,000 non-native species introduced to Hawai‘i, less than 10% of these are self-sustaining and 90 of those pose a danger to native biota and are considered invasive. In this paper, we explore the native/non-native binary, the impacts of globalization and the political language of invasion through the lens of conservation biology and sociology with a tropical island perspective. This lens gives us the opportunity to offer a place-based approach toward the use of empirical observation of novel species interactions that may help in evaluating management strategies that support biodiversity and ecosystem services. Finally, we offer a first attempt at conceptualizing a site-specific approach to develop “metrics of belonging” within an ecosystem.

Acute postoperative pain in 23 procedures of gynaecological surgery analysed in a prospective open registry study on risk factors and consequences for the patient

Effective perioperative pain management is essential for optimal patient recovery after surgery and reduces the risk of chronification. However, in clinical practice, perioperative analgesic treatment still needs to be improved and data availability for evidence-based procedure specific analgesic recommendations is insufficient. We aimed to identify procedures related with high pain scores, to evaluate the effect of higher pain intensity on patients and to define patient and intervention related risk factors for increased pain after standard gynaecological and obstetrical surgery. Therefore, we performed a prospective cross-sectional study based on the German registry for quality in postoperative pain (QUIPS). A cohort of 2508 patients receiving surgery between January 2011 and February 2016 in our tertiary referral centre (university departments of gynaecology and obstetrics, respectively) answered a validated pain questionnaire on the first postoperative day. Maximal pain intensity was measured by means of a 11-point numeric rating scale (NRS) and related to procedure, perioperative care as well as patient characteristics. The interventions with the highest reported pain scores were laparoscopic removal of ovarian cysts (NRS of 6.41 ± 2.12) and caesarean section (NRS of 6.98 ± 2.08). Factors associated with higher pain intensity were younger age (OR 1.75, 95% CI 1.65–1.99), chronic pain (OR 2.08, 95% CI 1.65–2.64) and surgery performed outside the regular day shift (OR 1.67, 95% CI 1.09–2.36). Shorter duration of surgery, peridural or local analgesic and preoperative sedation reduced postoperative pain. Patients reporting high pain scores (NRS ≥ 5) showed relevant impairment of daily activities and reduced satisfaction. Caesarean section and minimal invasive procedures were associated with the highest pain scores in the present ranking. Pain management of these procedures has to be reconsidered. Younger age, receiving surgery outside of the regular shifts, chronic pain and the surgical approach itself have a relevant influence on postoperative pain intensity. When reporting pain scores of 5 or more, patients were more likely to have perioperative complications like nausea or vomiting and to be impaired in mobilisation. Registry-based data are useful to identify patients, procedures and critical situations in daily clinical routine, which increase the risk for elevated post-intervention pain. Furthermore, it provides a database for evaluation of new pain management strategies.

Synthesis of Thresholds of Ocean Acidification Impacts on Decapods

Assessing decapod sensitivity to regional-scale ocean acidification (OA) conditions is limited because of a fragmented understanding of the thresholds at which they exhibit biological response. To address this need, we undertook a three-step data synthesis: first, we compiled a dataset composed of 27,000 datapoints from 55 studies of decapod responses to OA. Second, we used statistical threshold analyses to identify OA thresholds using pH as a proxy for 13 response pathways from physiology to behavior, growth, development and survival. Third, we worked with the panel of experts to review these thresholds, considering the contributing datasets based on quality of the study, and assign a final thresholds and associated confidence scores based on quality and consistency of findings among studies. The duration-dependent thresholds were within a pH range from 7.40 to 7.80, ranging from behavioral and physiological responses to mortality, with many of the thresholds being assigned medium-to-high confidence. Organism sensitivity increased with the duration of exposure but was not linked to a specific life-stage. The thresholds that emerge from our analyses provide the foundation for consistent interpretation of OA monitoring data or numerical ocean model simulations to support climate change marine vulnerability assessments and evaluation of ocean management strategies.

Evaluation of management strategies in patients with coronary ectasia: a retrospective cohort study

Abstract Background/Introduction Since patients with coronary ectasia have an increased risk of developing myocardial infarction and cardiovascular death, these patients could benefit from a more intensive treatment. Unfortunately, the evidence regarding outcomes with different management strategies is limited, especially with direct oral anticoagulants (DOAC). Purpose To compare clinical outcomes in patients with coronary ectasia based on the selected/chosen treatment strategy. Methods We conducted a retrospective cohort study in patients diagnosed with coronary artery ectasia. They were divided into 3 different groups based on the treatment they received at discharge and we evaluated the main cardiovascular outcomes at one-year follow-up. Results Between 2016 and 2019, 7,579 angiographies were performed, in which 510 patients with coronary ectasia were found (prevalence of 6.72%). Of these patients, 43.9% (n=224) had the diagnosis of STEMI, 21% NSTEMI (n=107), 5.1% unstable angina (n=26), 18.6% chronic stable angina (n=95) and other 11.4% (n=58). The angiographic distribution of the lesions was as follows: left main coronary artery 25.1%, Left descending coronary artery 62.7%, circumflex artery 52.1%, right coronary artery 79.2%. It was possible to obtain the follow-up of 363 patients (71.2%) because 25 died during their hospitalization and data of 122 were not available at the time of analysis. Three groups were formed based on the treatment: (1) Dual Antiplatelet Therapy (DAPT) in 47% (n=174); (2) DAPT + Vitamin K Antagonist (VKA) in 8.5% (n=31); (3) DAPT + DOAC in 6.6% (n=24). The overall MACE rate at 1-year of follow-up was 6.6% (n=15): 11 patients in the DAPT group (6.3%), 1 patient in the DAPT + VKA group (3.2%), and 3 patients in the DAPT + DOAC group (12.5%). During this period, 3 patients died from cardiovascular causes, all of them in the DAPT group. Myocardial infarction occurred in 12 patients, 8 in the DAPT group (4.2%), 1 in the DAPT + VKA group (3.2%) and 3 in the DAPT + DOAC group (12.5%). Stroke occurred in 2 patients: 1 patient in the DAPT group (0.5%) and 1 patient in the DAPT + DOAC group, 4.1% None of these findings were statistically significant. One-year occurrence of bleeding events was also evaluated: 23 patients presented a bleeding event, 14 in the DAPT group (8%), 7 in the DAPT + VKA group (22.5%) and 2 in the DAPT + DOAC group (8.3%); p=0.010. Conclusion(s) Our findings suggest that there is no statistically significant difference in the incidence of thrombotic complications, when comparing the treatment options. Patients using the combination of DAPT+VKA have a higher incidence of bleeding. Funding Acknowledgement Type of funding sources: None.

Early detection of onion neck rot disease in Manitoba

Neck rot caused by the fungus Botrytis allii Munn. is one of the most devastating diseases of onions (Allium cepa L.), resulting in significant yield losses. This disease is latent in nature developing symptomless onion plants in the field with bulbs typically showing symptoms 1–2 months after harvest in the storage. Molecular studies were conducted to detect latent infections of Botrytis neck rot in the onion fields of Manitoba, Canada. Plant samples of onion cultivars ‘Redwing’ and ‘Pocono’ were collected every 10 days throughout the growing season, starting from planting until bulb harvesting during 2018, 2019, and 2020 from a research farm in Brandon, Manitoba, and plant samples of ‘Redwing’ were collected during 2019 and 2020 from a commercial vegetable farm in Portage La Prairie, Manitoba. The amplified DNA fragment of onion leaves and the neck region of collected samples were subjected to polymerase chain reaction using the Botrytis-specific primer pair BA2f/BA1r. Botrytis allii was detected on onion samples collected from the commercial farm as early as the end of June 2019 and 2020 when plants were at the 5–7 leaf stage. The majority of onion samples collected from the research farm also started testing positive for the pathogen from June (2019, 2020) and July (2018) onwards. This knowledge about the timing of infection in the field will be useful in helping farmers to develop and evaluate management strategies in the field, and also predict the storability and availability of quality bulbs for sale.

Development and Evaluation of Velocity Predictive Optimal Energy Management Strategies in Intelligent and Connected Hybrid Electric Vehicles

In this study, a thorough and definitive evaluation of Predictive Optimal Energy Management Strategy (POEMS) applications in connected vehicles using 10 to 20 s predicted velocity is conducted for a Hybrid Electric Vehicle (HEV). The presented methodology includes synchronous datasets gathered in Fort Collins, Colorado using a test vehicle equipped with sensors to measure ego vehicle position and motion and that of surrounding objects as well as receive Infrastructure to Vehicle (I2V) information. These datasets are utilized to compare the effect of different signal categories on prediction fidelity for different prediction horizons within a POEMS framework. Multiple artificial intelligence (AI) and machine learning (ML) algorithms use the collected data to output future vehicle velocity prediction models. The effects of different combinations of signals and different models on prediction fidelity in various prediction windows are explored. All of these combinations are ultimately addressed where the rubber meets the road: fuel economy (FE) enabled from POEMS. FE optimization is performed using Model Predictive Control (MPC) with a Dynamic Programming (DP) optimizer. FE improvements from MPC control at various prediction time horizons are compared to that of full-cycle DP. All FE results are determined using high-fidelity simulations of an Autonomie 2010 Toyota Prius model. The full-cycle DP POEMS provides the theoretical upper limit on fuel economy (FE) improvement achievable with POEMS but is not currently practical for real-world implementation. Perfect prediction MPC (PP-MPC) represents the upper limit of FE improvement practically achievable with POEMS. Real-Prediction MPC (RP-MPC) can provide nearly equivalent FE improvement when used with high-fidelity predictions. Constant-Velocity MPC (CV-MPC) uses a constant speed prediction and serves as a “null” POEMS. Results showed that RP-MPC, enabled by high-fidelity ego future speed prediction, led to significant FE improvement over baseline nearly matching that of PP-MPC.

Application of explicit precautionary principles in data-limited fisheries management

Abstract Many management bodies require applying the precautionary approach when managing marine fisheries resources to achieve sustainability and avoid exceeding limits. For data-limited stocks, however, defining and achieving management objectives can be difficult. Management procedures can be optimized towards specific management objectives with genetic algorithms. We explored the feasibility of including an objective that limited the risk of a stock falling below various limit reference points in the optimization routine for an empirical data-limited control rule that uses a biomass index, mean catch length, and includes constraints (the “rfb-rule”). This was tested through management strategy evaluation on several fish stocks representing various life-history traits. We show that risk objectives could be met, but more restrictive risk limits can lead to a potential loss of yield. Outcomes were sensitive to simulation conditions such as observation uncertainty, which can be highly uncertain in data-limited situations. The rfb-rule outperforms the method currently applied by ICES, particularly when risk limitation objectives are considered. We conclude that the application of explicit precautionary levels is useful to avoid overfishing. However, we caution against the indiscriminate use of arbitrary risk limits without scientific evaluation to analyse their impact on stock yields and sustainability.

(Micro)plastics: A possible criterion for beach certification with a focus on the Blue Flag Award

On the one hand, environmental certifications like the Blue Flag award (BFA) are well-known globally for its role in beach management and tourism attraction. Plastic pollution like microplastics, on the other hand, has become a global concern due to their increasing persistence and negative environmental repercussions. This paper examines and discusses the factors that would lead to (micro)plastics being included to the BFA as a criterion. Thereby, we attempt to maximize BFA's potential as a tool for better understanding (micro)plastics on beaches and implementing strategies to reduce them. The anticipated primary benefits are: 1) knowing the degree of litter disposal and microplastic contamination, 2) conducting close monitoring, 3) having an accessible database for numerous coastlines throughout the world, 4) evaluating management strategies and making improvements, 5) assisting in long-term research, 6) having a responsible entity in charge of issue decision-making, and 7) a larger public/scientific outreach.

Implementing the precautionary approach into fisheries management: Biomass reference points and uncertainty buffers

AbstractThe precautionary approach to fisheries management advocates for risk‐averse management strategies that include biological reference points and account for scientific uncertainty (i.e. process, model and observation uncertainty). In this regard, two approaches have been recommended: (a) biomass reference points to safeguard against low stock biomass, and (b) uncertainty buffers that reduce the catch limit as a function of the scientific uncertainty. This study compares the effectiveness of these two precautionary approaches in recovering over‐exploited fish stocks. We evaluate the performance of more than 80 harvest control rules (HCRs) within a stochastic management strategy evaluation (MSE) framework for three stocks with contrasting life‐history parameters and under various levels of scientific uncertainty. The results show that both approaches reduce the risk of overfishing at the expense of expected yield. This risk‐yield trade‐off strongly depends on the HCRs, life‐history parameters of the species, as well as the level of the scientific uncertainty. Nevertheless, some combinations of biomass threshold and limit reference points as well as uncertainty buffers lead to a more favourable risk‐yield trade‐off than other rules. This study elucidates the multiple factors affecting the effectiveness of management strategies and highlights key features of HCRs for precautionary fisheries management.

Profitability of farm-scale management strategies against the boll weevil in the tropics: case study from the Colombian Caribbean

Decision making in pest management is a challenging task. While pest dynamics are often quite uncertain, such decisions are often based on tenuous assumptions of certainty (economic injury levels and marginal utility approximations). To overcome such assumptions and adequately consider uncertainty, we apply decision analysis to evaluate management strategies used by farmers in the Colombian Caribbean against the boll weevil (BW). We represent the decision to protect the crop using partial budget analysis. This allows us to capture key properties of BW control strategies, while accounting for uncertainty about pest infestation pressure, control effectiveness and cotton yield and price. Our results indicate that proactive pest management is more efficient than reactive control given the current BW infestation pressure. However, farmers may prefer the reactive strategy, since they have experienced seasons with low infestation pressure where no insecticide applications were required. The proactive strategy, in contrast, requires scheduled pesticide applications in all years. Results show that in seasons with high infestation pressure the expected revenues of the reactive strategy tend to decrease, mainly because more spray applications are required when fields are heavily infested by the weevil. Value of information analysis revealed that uncertainties related to the start of the infestation, loss damage rate and attainable yield have the greatest influence on the decision recommendation for crop protection. Narrowing these key knowledge gaps may offer additional clarity on the performance of the current management strategies and provide guidance for the development of strategies to reduce insecticide use. This is particularly important for the promotion of the proactive strategy, which, under the current infestation pressure, has potential to reduce insecticide use. While economic injury levels can only be applied to responsive measures, our approach of partial budget analysis under uncertainty allows us to assess and compare both responsive and preventive measures in the same methodological framework. This framework can be extended to non-pesticide control measures.

To be or not to be a target: that is the question to manage mixed fisheries

Abstract Simulation models are used extensively to evaluate the performance of fisheries management strategies, though they must be validated to ensure that they accurately represent the real system. One of the quantitative methods available to advance in the process of validating simulation models is global sensitivity analysis (GSA). However, its use in fisheries management has been very limited. When GSA is applied to management strategy evaluation implementations, it can also help manage available resources efficiently with respect to uncertainty in the management process and the conditioning of simulation models. Mixed-fisheries management plans were recently implemented for demersal fisheries in the Northeast Atlantic, which were evaluated previously using complex bioeconomic models. Here, we applied GSA to the model used in Iberian waters, employing an efficient model design to introduce uncertainty in every single input factor. While most biological factors contributed significantly to the variance of results, only few economic factors did. Moreover, we found that increasing accuracy in the stock assessment process would mainly impact management advice and that only the management of target stocks had a real impact on the system. This highlights the importance of properly managing hake (Merluccius merluccius), which is currently managed using an empirical harvest control rule.

A Quick Method for Estimating Batch Fecundity in Bigheaded Carp

AbstractFecundity is a necessary metric to assess reproductive potential (e.g., spawning potential ratio and recruitment overfishing) in invasive fishes, yet the direct measurement of fecundity is often difficult, impractical, and time consuming. Therefore, the ability to estimate fecundity from field measurements (i.e., TL, relative weight [Wr], or ovary weight) can be a valuable tool for fisheries managers to estimate reproductive potential. The goal of this study was to relate the batch fecundity of invasive Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis to metrics that can be quickly measured to eliminate the need for direct enumeration. Silver and Bighead carp were collected from the upper Mississippi River (UMR) in the summer of 2016 and 2017. Subsamples of mature (spawning capable) ovaries were preserved, enumerated, and then related to ovary weight, TL, weight, and Wr. An equation for estimating Silver Carp batch fecundity from ovary weight in the UMR, corrected for ovary membrane weight, was developed: {ovary weight – [0.222 × (ovary weight0.7589)]} × 794 (SE = 11). Batch fecundity for Silver Carp from Pools 17–20 of the UMR averaged 1,230,930 ± 68,983 eggs (mean ± SE). Ovary weight was the strongest predictor of fecundity, but TL, weight, and Wr also showed significant relationships with fecundity for Silver Carp. Batch fecundity for Bighead Carp averaged 1,043,953 ± 82,360 eggs, but the number of eggs per gram showed significant spatial variation; therefore, no fecundity equation was developed for this species. Future work should evaluate the frequency of Silver Carp spawns within a season and how batch fecundity varies among multiple spawning events. Fecundity estimates can be used to determine spawning potential ratios, which can help in evaluating management strategies.

Trade-offs and uncertainties in Northeast Pacific herring fisheries: ecosystem modelling and management strategy evaluation

AbstractPacific 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.

Domestic Cat Abundance and Activity Across a Residential Land Use Gradient

Free-ranging domestic cats are a detriment to wildlife and humans by preying on native species and transmitting disease. As a result, removing free-ranging cats from the landscape has become a conservation and public health priority. Estimating cat population size with an unbiased sampling design, however, especially in human-dominated areas, is logistically challenging and rarely done. The lack of robust cat population sampling limits our understanding of where cats pose risks, which is important for evaluating management strategies, such as trap-remove or trap-neuter-return. We hypothesized that cat abundance and activity both depend on human land use and demographics. Using a network of sites participating in a community science program, we conducted transect and camera trap surveys to test predictions of cat population abundance and activity across a gradient of residential land use intensity. Both sampling methods determined that cat abundance was greatest in areas with intermediate human population density and lower educational attainment. Transect data also provided evidence that cat abundance was greatest at intermediate levels of impervious surface cover (e.g., road and buildings), while data from camera traps also showed that cat abundance was positively associated with household income. Using counts of cats observed on cameras, we found that the timing of cat activity varied depending on the degree of urban intensity. Cats were more strictly nocturnal in medium and high intensity residential land-use areas, possibly because a greater proportion of these cats are unowned or because they avoid human activity. These results suggest that transect surveys conducted during the day may undercount cats in urban environments where unowned free-ranging cats predominate. Taken together, our results highlight the importance of incorporating human demographics, land use patterns, and urban context in estimating the abundance of free-ranging cats to better inform management decisions and improve conservation outcomes.

Evaluation of e-waste status, management strategies, and legislations

Evaluation of e-waste status, management strategies, and legislations

Evaluating the Impact of Recreational Harvest and Management Strategies for Bay Scallops Argopecten irradians concentricus in a Florida Gulf Coast Management Zone

AbstractSince 1994, the fishery for bay scallops Argopecten irradians concentricus in Florida has been limited to a recreational fishery that operates during the summer, before the spawning season in fall. Recent growth of the fishery necessitates a study of the effect of this increased exploitation on the bay scallop population. The study focused on one management zone, centered on the community of Steinhatchee, that is known for high rates of exploitation. Within this zone, we created a model of bay scallop harvest using fishery‐independent and fishery‐dependent survey methods and evaluated the risk of extirpation of the stock. We found that the fishery in the zone functions as a derby, with most harvest effort occurring when the season opens, followed by a steady decline throughout the season. Effort estimates suggest that 21,579 vessels, or 82,398 people, from 94% of Florida’s counties and 16 other states participated in the 2018 season in the Steinhatchee zone. The influx of harvesters generated approximately US$1.8 million in revenue for this small coastal community and resulted in an estimated fishing mortality of 57–72% of the population in the zone. The exploitation rate of the fishery in 2018 exceeded 0.4, suggesting that the fishery may be unable to sustain itself under current conditions. We evaluated management strategies and found that the bay scallop population in this zone would be in danger of being extirpated if harvest effort doubled, suggesting the need for regular monitoring of effort in this fishery in this zone and probably in the fishery statewide.

Should harvest control rules for male-only fisheries include reproductive buffers? A Bering Sea Tanner crab (Chionoecetes bairdi) case study

Highly variable recruitment and a complex harvest strategy resulted in dramatic inter-annual changes in historical catches, including prolonged closure periods, for Bering Sea Tanner crab (Chionoecetes bairdi). Current management regulations, linked to recent frequent closures, led to an industry-initiated cooperative effort to reevaluate the harvest control rule (HCR) that forms part of the State of Alaska harvest strategy. Management strategy evaluation (MSE) was used to assess conservation and economic trade-offs of fifteen HCR options that differed in how females were considered. Several male-only HCRs performed similarly to those that accounted for females. However, the inclusion of both sexes reflected conservation and economic objectives while acknowledging the uncertainty around reproductive dynamics. The HCR selected by the Alaska Board of Fisheries included a threshold for opening the fishery based on mature male biomass (MMB), scalars based on relative levels of mature female biomass (MFB) and MMB that determine the exploitation rate on MMB, and a maximum exploitation cap on industry-preferred sizes of legal males. This work illustrates how manager-stakeholder collaboration may enable improved fishery management. Our analysis provided managers with a tool to facilitate productive and transparent dialogue with industry, with the goal of accounting for conservation and economic objectives, given some of the underlying biological uncertainty associated with reproductive dynamics. This study demonstrates that the inclusion of reproductive buffers in HCRs for male-only fisheries may be able to better achieve conservation goals without sacrificing economic performance.

Management Strategy Evaluation: Allowing the Light on the Hill to Illuminate More Than One Species

Management strategy evaluation (MSE) is a simulation approach that serves as a “light on the hill” (Smith, 1994) to test options for marine management, monitoring, and assessment against simulated ecosystem and fishery dynamics, including uncertainty in ecological and fishery processes and observations. MSE has become a key method to evaluate trade-offs between management objectives and to communicate with decision makers. Here we describe how and why MSE is continuing to grow from a single species approach to one relevant to multi-species and ecosystem-based management. In particular, different ecosystem modeling approaches can fit within the MSE process to meet particular natural resource management needs. We present four case studies that illustrate how MSE is expanding to include ecosystem considerations and ecosystem models as ‘operating models’ (i.e., virtual test worlds), to simulate monitoring, assessment, and harvest control rules, and to evaluate tradeoffs via performance metrics. We highlight United States case studies related to fisheries regulations and climate, which support NOAA’s policy goals related to the Ecosystem Based Fishery Roadmap and Climate Science Strategy but vary in the complexity of population, ecosystem, and assessment representation. We emphasize methods, tool development, and lessons learned that are relevant beyond the United States, and the additional benefits relative to single-species MSE approaches.

Considerations for management strategy evaluation for small pelagic fishes

AbstractManagement strategy evaluation (MSE) is the state‐of‐the‐art approach for testing and comparing management strategies in a way that accounts for multiple sources of uncertainty (e.g. monitoring, estimation, and implementation). Management strategy evaluation can help identify management strategies that are robust to uncertainty about the life history of the target species and its relationship to other species in the food web. Small pelagic fish (e.g. anchovy, herring and sardine) fulfil an important ecological role in marine food webs and present challenges to the use of MSE and other simulation‐based evaluation approaches. This is due to considerable stochastic variation in their ecology and life history, which leads to substantial observation and process uncertainty. Here, we summarize the current state of MSE for small pelagic fishes worldwide. We leverage expert input from ecologists and modellers to draw attention to sources of process and observation uncertainty for small pelagic species, providing examples from geographical regions where these species are ecologically, economically and culturally important. Temporal variation in recruitment and other life‐history rates, spatial structure and movement, and species interactions are key considerations for small pelagic fishes. We discuss tools for building these into the MSE process, with examples from existing fisheries. We argue that model complexity should be informed by management priorities and whether ecosystem information will be used to generate dynamics or to inform reference points. We recommend that our list of considerations be used in the initial phases of the MSE process for small pelagic fishes or to build complexity on existing single‐species models.

Validation of stock assessment methods: is it me or my model talking?

Abstract The adoption of the Precautionary Approach requires providing advice that is robust to uncertainty. Therefore, when conducting stock assessment alternative, model structures and data sets are commonly considered. The primary diagnostics used to compare models are to examine residuals patterns to check goodness-of-fit and to conduct retrospective analysis to check the stability of estimates. However, residual patterns can be removed by adding more parameters than justified by the data, and retrospective patterns removed by ignoring the data. Therefore, neither alone can be used for validation, which requires assessing whether it is plausible that a system identical to the model generated the data. Therefore, we use hindcasting to estimate prediction skill, a measure of the accuracy of a predicted value unknown by the model relative to its observed value, to explore model misspecification and data conflicts. We compare alternative model structures based on integrated statistical and Bayesian state-space biomass dynamic models using, as an example, Indian Ocean yellowfin tuna. Validation is not a binary process (i.e. pass or fail) but a continuum; therefore, we discuss the use of prediction skill to identify alternative hypotheses, weight ensemble models and agree on reference sets of operating models when conducting Management Strategy Evaluation.