Management Reference Points Research Articles

Confronting transitions in fishery fleet structure and selectivity: practical recommendations for integrated age-structured stock assessments based on simulation analysis

Dynamic shifts in fleet structure and gear usage lead to complex implications for representing fishery selectivity in stock assessment models. There is generally a lack of consensus on how assessment models should be configured to confront changes in fishery fleet structure or associated selectivity forms, while balancing complexity-parsimony tradeoffs. We conducted a simulation analysis to evaluate the performance of alternative assessment models when confronted with fleet transitions among gear types, which included differences in (1) rates of transition (i.e., a fast or slow transition among gears), and (2) selectivity forms for each modeled fleet (i.e., asymptotic or dome-shaped). In general, explicitly modeling fleet structure (i.e., multi-fleet models) performed well, but demonstrated bias in biomass estimates and management reference points when selectivity forms were mis-specified. Single-fleet models were only unbiased when time-varying selectivity (e.g., using time blocks or continuous formulations) was estimated to account for changes among gear types. Our results suggest that single-fleet models with time-varying fishery selectivity are adequate for operational management advice, but research oriented multi-fleet models should be used as validation tools to explore model consistency within single-fleet models.

SRU TGTU Hydrogenation Catalyst Lifecycle Best Practices

This report highlights the best practices captured in the management of Tail-Gas Treatment Unit (TGTU)’s hydrogenation CoMo catalyst throughout its lifecycle, these best practices were developed based on success story in operating the TGTU, which provides technical framework to manage TGTU unit performance throughout TGTU catalyst lifecycle. The aforementioned TGTU CoMo catalyst management best practices span across the whole catalyst lifecycle, starting from cradle stage of activating/sulphiding the fresh oxide-form catalyst up to grave stage of unloading & handling the spent catalyst to a safe location. Furthermore, stressing points have been provided to record special procedure to activate catalyst’s active sites (Cobalt & Molybdenum) in a process commonly known as “sulphiding”, as well as “passivation” procedure during TGTU catalyst unloading due to the presence of pyrophoric material such as Iron Sulphide (FeS) in the TGTU converter. This developed best practices provide solid reference point for future TGTU catalyst management throughout its lifecycle. Therefore, it can be adopted and consistently applied across other TGTU-based Sulfur Recovery Unit (SRU) plants in order to maintain the optimum Sulfur Recovery Efficiency (SRE), minimize plant downtime due to catalyst replacement and prevent unwanted environmental issues such as SO<sub>x</sub> emissions).

On the probable distribution of stock-recruitment resilience of Pacific saury (Cololabis saira) in the Northwest Pacific Ocean

Abstract Determining how resilient a stock-recruitment relationship is to environmental variation is crucial for fisheries management. Steepness is a key factor characterizing the resilience of a fish stock and, hence, for establishing management reference points. This study estimates the distribution of steepness for Pacific saury using a simulation approach based on evolutionary ecology and reproductive biology, and how it changes in response to environmental change. The median estimated steepness is 0.82 (80% probable range 0.59, 0.93) based on the best available biological information, which suggests that Pacific saury can produce a relatively high proportion of unfished recruitment when depleted to 20% of unfished spawning biomass. Elasticity analysis indicates that steepness for Pacific saury is most sensitive to the survival rate of early life stages, mean body weight, growth, and length-at-maturity. Environmental change could substantially impact steepness, with unfavorable conditions related to survival rates, length-at-maturity, mean body weight, and growth potentially leading to a reduction in resilience. Understanding these impacts is crucial for the assessment and management of Pacific saury. Our numerical simulation approach provides an analytical tool applicable for calculating the steepness distribution in other small pelagic fish influenced by increases in sea surface temperature due to global warming.

Flood risk transfer analysis based on the “Source-Sink” theory and its impact on ecological environment: A case study of the Poyang Lake Basin, China

Driven by climate change, the frequent occurrence of regional destructive floods poses a grave threat to socio-economic systems and ecological environments. Previous flood risk studies have disregarded risk transfer within a region, resulting in inadequate flood risk assessment and ineffective disaster prevention and mitigation outcomes. Therefore, this study introduced the “Source-Sink” theory into flood disaster field to constructing flood risk transfer model. Flood risk assessment and transfer was conducted in the Poyang Lake Basin, China, where the impacts of the initial and transfer statuses on ecosystem service values were quantified. The results showed that the flood risk in the Poyang Lake Basin was relatively low, with high spatial distribution characteristics in the central-north areas but low in the surrounding areas. High-risk zones were mainly distributed southwest of the Poyang Lake. The lower-risk zones exhibited a contiguous distribution and were surrounded by higher-risk zones. Following the completion of the flood risk transfer, high-risk zones increased significantly; but there were a few zones where the risk was transferred to other zones, thereby lowering their risks. Flood risk transfer occurs primarily in low- and medium-risk zones, with high-risk zones being the most important growth targets. The change in risk transfer was most evident in the area surrounding Poyang Lake, while that in the Upper Gan River Basin was lower and less sensitive to the transfer effect. Accounting for flood disaster risk, the ecosystem service values of the Poyang Lake Basin decreased by 8.18 %, with the most significant impacts observed in the surrounding environment and southwest Poyang Lake. After the completion of the flood risk transfer, the ecosystem service value in the Poyang Lake Basin declined by 24.66 %. This study provides a reference point for flood risk management and sustainable regional development that account for risk transfer.

Correction: Accounting for transient dynamics could improve the use of marine protected areas as a reference point for fisheries management

Correction: Accounting for transient dynamics could improve the use of marine protected areas as a reference point for fisheries management

State of knowledge of aquatic ecosystem and fisheries of the Lake Edward System, East Africa

AbstractPoor and unreliable knowledge of the status of freshwater fisheries limits their inclusion in governance processes, thereby impeding effective management measures. This threatens the livelihoods of people, particularly in developing countries. Improved knowledge is required to draw the attention of policymakers and stimulate effective management measures to accelerate the sustainability of the freshwater fisheries. In line with this requirement, this paper provides the state of knowledge of the aquatic ecosystem and fisheries of the Lake Edward system, East Africa, focusing on lakes Edward, George and the Kazinga channel. The state of knowledge was accomplished by reviewing existing data and information on aspects of primary productivity and water quality, invertebrates, fish fauna, fish life history and ecology, and fisheries. The waterbodies have been monitored since the 1930s, albeit sporadically, providing data on all the above aspects but with substantial temporal gaps. Adequate and updated data and information exist on the water quality status of the water bodies, extant aquatic taxa (including fishes) and fish catches but with uncertainties in the latter. Data and information gaps exist on the abundance of biotic communities, fish life history, quantitative trophic ecology and fisheries management reference points. The aggregated data and information can directly support decisions for fisheries management. We recommend regular monitoring to fill the data and information gaps, more comprehensive stock assessments and the development of aquatic ecosystem models.

Trees for fishes: The neglected role for phylogenetic comparative methods in fisheries science

AbstractFisheries scientists compare processes among species to estimate species productivity, management reference points, and climate sensitivities. Ecologists have developed “phylogenetic comparative methods” (PCMs) to address these questions, but there is surprisingly little application of PCM within fisheries science. Here, I bridge this gap by introducing PCM (including Brownian motion, Ornstein–Uhlenbeck, and Pagel's kappa and lambda models for species covariance), thereby showing that PCM generalizes the nested taxonomic random effects that are commonly used in fisheries science. I next summarize phylogenetic structural equation models (PSEMs), which extend the linear models that are commonly used in fisheries. Finally, I re‐analyse a high‐quality database used to predict mortality rates from longevity and/or growth parameters. I specifically propose a PSEM that reverts to a longevity‐based prediction when longevity information is available but uses phylogenetic corrected growth parameters otherwise. Using this single PSEM replaces the common practice of fitting and predicting using separate linear models depending upon what data are available for a given species. Cross‐validation suggests that the relationship between log‐mortality rate and longevity does not vary based on phylogeny, and therefore, linear models and PSEM both explain 82% of variance when longevity is available. When longevity is unavailable, by contrast, the linear model explains only 37% of variance while the PSEM explains 52% of variance, where this gain occurs from conditioning predictions on phylogenetic similarities. I therefore conclude that PCM and PSEM provide a general and user‐friendly replacement for linear models and can improve performance for fisheries meta‐analyses that are used for fisheries management applications.

Highlights on the Bio-Economic Reference Points for Fisheries Management and Planning

A brief discussion on the main processes ruling the exploitation of fish stocks is given. Comments on the content of main issues in stock assessment are provided.

Genesis and key elements of the mechanism of digital transformation of industrial enterprises

Aim. To study the peculiarities of different approaches to the construction of the mechanism of digital transformation of industrial enterprises and to identify the key elements, the creation and (or) development of which is necessary for the realisation of successful digital transformation.Tasks. To study the Russian and world experience in the field of building the mechanism of digital transformation of enterprises; to generalise and systematise various approaches; to form an integral set of key elements, the transformation of which is necessary to ensure competitiveness in the digital environment.Methods. The subject of the study are mechanisms, models and methods of digital transformation of enterprises developed by large global and Russian companies, mainly consulting companies. The analysis takes into account the presence of a clear system of principles (priorities), substantive aspects, structuring of various mechanisms by stages and elements of digital transformation, the level of specificity of proposed solutions, as well as additional features (for example, the presence of a model for assessing the digital maturity of the enterprise).Results. The key elements of the mechanism of digital transformation of an industrial enterprise are identified: digital strategy, business model, digital core and digital technologies, operating model, people and organisational culture, orchestration. It is shown that when developing a digital strategy, it is necessary to maximise the use of the enterprise’s competitive advantages (e.g., developed partner network, unique equipment and technologies, a wide range of goods and services, customer databases, etc.), as well as ecosystem opportunities. To increase the flexibility of the strategy, it is proposed to focus on the concept of strategic priorities. Emphasis is placed on the importance of aligning digital strategy with the operating model of an industrial enterprise. As a promising direction of digital transformation, the creation of a “digital core” of the enterprise, which unites all information systems, applications, services and data through the cloud in order to integrate technological and organisational aspects of digital transformation across the entire value chain, including partners and customers, is highlighted.Conclusions. The presented developments can serve as a reference point for managers of industrial enterprises developing and implementing digital transformation programmes.

A Bibliometrics-Based Systematic Review of Safety Risk Assessment for IBS Hoisting Construction

Construction faces many safety accidents with urbanization, particularly in hoisting. However, there is a lack of systematic review studies in this area. This paper explored the factors and methods of risk assessment in hoisting for industrial building system (IBS) construction. Firstly, bibliometric analysis revealed that future research will focus on “ergonomics”, “machine learning”, “computer simulation”, and “wearable sensors”. Secondly, the previous 80 factors contributing to hoisting risks were summarized from a “human–equipment–management–material–environment” perspective, which can serve as a reference point for managers. Finally, we discussed, in-depth, the application of artificial neural networks (ANNs) and digital twins (DT). ANNs have improved the efficiency and accuracy of risk assessment. Still, they require high-quality and significant data, which traditional methods do not provide, resulting in the low accuracy of risk simulation results. DT data are emerging as an alternative, enabling stakeholders to visualize and analyze the construction process. However, DT’s interactivity, high cost, and information security need further improvement. Based on the discussion and analysis, the risk control model created in this paper guides the direction for future research.

Industrial fisheries have reversed the carbon sequestration by tuna carcasses into emissions.

To limit climate warming to 2°C above preindustrial levels, most economic sectors will need a rapid transformation toward a net zero emission of CO2 . Tuna fisheries is a key food production sector that burns fossil fuel to operate but also reduces the deadfall of large-bodied fish so the capacity of this natural carbon pump to deep sea. Yet, the carbon balance of tuna populations, so the net difference between CO2 emission due to industrial exploitation and CO2 sequestration by fish deadfall after natural mortality, is still unknown. Here, by considering the dynamics of two main contrasting tuna species (Katsuwonus pelamis and Thunnus obesus) across the Pacific since the 1980s, we show that most tuna populations became CO2 sources instead of remaining natural sinks. Without considering the supply chain, the main factors associated with this shift are exploitation rate, transshipment intensity, fuel consumption, and climate change. Our study urges for a better global ocean stewardship, by curbing subsidies and limiting transshipment in remote international waters, to quickly rebuild most pelagic fish stocks above their target management reference points and reactivate a neglected carbon pump toward the deep sea as an additional Nature Climate Solution in our portfolio. Even if this potential carbon sequestration by surface unit may appear low compared to that of coastal ecosystems or tropical forests, the ocean covers a vast area and the sinking biomass of dead vertebrates can sequester carbon for around 1000 years in the deep sea. We also highlight the multiple co-benefits and trade-offs from engaging the industrial fisheries sector with carbon neutrality.

Reference Point Calculator (RPC): A Shiny app for exploration of limit reference points for fisheries management

Reference Point Calculator (RPC): A Shiny app for exploration of limit reference points for fisheries management

Biphasic versus monophasic growth curve equation, an application to common sole (Solea solea, L.) in the northern and central Adriatic Sea

Traditionally, growth patterns are described as constant throughout life using von Bertalanffy's equation. However, a change in growth due to a reallocation of energy during an individual’s lifespan is to be expected. Following this hypothesis, back-calculation measurements obtained from SoleMon survey data were used to fit and compare monophasic and biphasic growth curves for common sole in the northern and central Adriatic Sea. Moreover, individual variability in growth was considered through nonlinear mixed-effect models in which the individual parameters were considered as a random effect. The analyses performed in this study revealed systematic age-specific discrepancies in the monophasic curve and demonstrated that the fit of the biphasic curve was superior (Δ AIC: 329; Δ BIC: 310), confirming the theory that growth in size would decrease as a consequence of reproductive effort. Finally, since common sole is routinely assessed using models that rely on growth to derive assessment estimates and related management reference points, a stock assessment simulation was performed to compare the two growth alternatives. The results showed how the biphasic alternative was preferable to the conventional alternative and how the use of the monophasic pattern would result in an overly optimistic view of stock status (+40% in SSB/SSBtarget and −35% in F/Ftarget compared to the biphasic pattern), thereby increasing the risk of overfishing.

Contrasting stock status trends obtained from survey and fishery CPUE, taking Larimichthys polyactis in Yellow Sea Large Marine Ecosystem as an example

Biological conservation of exploited fish species involves characterizing key aspects of their population dynamics using models as tools to estimate their biomass. The Bayesian state-space surplus production model in the open-source stock assessment tool Just Another Bayesian Biomass Assessment (JABBA) was used to assess small yellow croaker stock (Larimichthys polyactis) in the Yellow Sea large marine ecosystem (YSLME). In this study, Catch and the scientific survey catch per unit effort (CPUE) data of the overwintering grounds of small yellow croaker from 1985 to 2020 and three fishery CPUE data series (one original and two reconstructed) from the Chinese Fishery Statistical Yearbook were used to fit JABBA, respectively. The results showed that the trends in biomass obtained from the survey CPUE and from the fishery CPUE contrasted sharply. The independent survey CPUE-based JABBA showed a 54.4 % probability that the current resource status is over exploited (0.65 and 1.06 for B2020/BMSY and F2020/FMSY, respectively), whereas the fishery CPUE-based JABBA showed that the resource is in a healthy or recovering state (0.88–1.32 and 0.40–0.70 for B2020/BMSY and F2020/FMSY, respectively), and the estimates of the resource are overly optimistic. This discrepancy in biomass assessment arises because the fishing effort time series does not adequately reflect the technological advances in fishing vessels and their equipment. Therefore, assessment based on survey CPUE (predicted total allowable catch, TAC = 150,000 tons) is the preferable, more precautionary approach for establishing management reference points and informing management decisions, and estimates generated from the fisheries CPUE-based JABBA model (TAC = 165,000–210,000 tons) should be treated with caution. We found that the two reconstructed fishery CPUEs are more likely to produce model results closer to that of the survey CPUE-based JABBA than the original fishery CPUE. Further review and research on the correction of fishing effort and fishery CPUE in the YSLME is recommended before this data series is used in assessments aimed at biological conservation.

Exploring reconfiguration of trends in CPUE to model sustainable TAC options for the pivotal YSLME anchovy fishery

Sustainable utilization of exploited fish stocks generally relies on characterizing key aspects of their population dynamics using mathematical models to evaluate their stock status. In this study, the Anchovy population (Engraulis japonicus) in the Yellow Sea large marine ecosystem (YSLME) was evaluated by using the ‘Just Another Bayesian Biomass Assessment’ (JABBA) model. Catch and the anchovy scientific survey biomass index data from 1989 to 2021 in its nominal or raw form, plus three adjusted CPUE trends using data acquired from the China Fishery Statistical Yearbook were each used to fit JABBA to explore the performance of reconfigured CPUE for setting a total allowable catch (TAC) quota to sustain the YSLME commercial anchovy fishery. Results showed contrasting trends in estimated biomass from the fishery independent surveys, and nominal and reconfigured commercial fishery CPUE, with the latter producing the most plausible results. The JABBA output based on the scientific survey biomass index indicated a 56.7% probability that the anchovy stock is currently healthy with 1.04B2021/BMSYand 0.51F2021/FMSYratios, whereas JABBA estimates based on the nominal commercial CPUE-based were overly optimistic (100% probability stock was healthy). JABBA outputs based on the first two reconfigured CPUEs (FacpueyandFECcpuey) countered this overoptimism, with the survey biomass index-based assessment results lying between the extremes. This improvement in the modelled assessment was achieved because the reconfigured CPUE time series accommodated technological progress in fishing vessels and gear performance. Therefore, in instances where survey biomass index data are unavailable, we recommend using the two improved fishery CPUEs and combining the results of the two assessments to guide fishery management. Management reference points, however, should preferably be based on the more conservative of the two reconfigured CPUEs as a precautionary approach for setting a total allowable catch (TAC) whilst concomitantly considering the role of anchovy as prey for other economically important fish in the system.We encourage researchers to extensively review and improve the quality and availability of fisheries statistical data worldwide in the shared endeavour towards obtaining more realistic stock assessments.

Barriers to implementation of dynamic reference points in fisheries management

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.

Risk equivalence in data‐limited and data‐rich fisheries management: An example based on the ICES advice framework

AbstractFisheries management needs to ensure that resources are exploited sustainably, and the risk of depletion is at an acceptable level. However, often uncertainty about resource dynamics exists, and data availability may differ substantially between fish stocks. This situation can be addressed through tiered systems, where tiers represent different data limitations, and tier‐specific stock assessment methods are defined, aiming for risk equivalence across tiers. As case studies, we selected stocks of European plaice, Atlantic cod and Atlantic herring, where advice is provided by the International Council for the Exploration of the Sea (ICES). We conducted a closed‐loop simulation to compare risk equivalence between the data‐rich ICES MSY rule, based on a quantitative stock assessment, and the revised data‐limited empirical management procedures of the ICES advice framework. The simulations indicated that the data‐limited approaches were precautionary and did not lead to a higher risk of depletion than the data‐rich approach. Although the catch based on generic data‐limited approaches was lower, stock‐specific optimisation improved management performance with catch levels comparable with the data‐rich approach. Furthermore, the simulation indicated the ICES MSY rule can fail to meet management objectives due to increased depletion risk when management reference points are set suboptimally. We conclude that the recent revisions of the ICES system explicitly account for risk equivalence for data‐limited fisheries management and are a major step forward. Finally, we advocate further consideration of simple empirical management procedures irrespective of data limitations due to their ability to meet fisheries management objectives with greater simplicity.

Accounting for transient dynamics could improve the use of marine protected areas as a reference point for fisheries management

Biological reference points for fishery management depend on estimates of current stock status relative to unfished biomass (depletion). The ratio of fish density outside to inside a marine reserve, the density ratio, could serve as a proxy for depletion for data-poor management. However, transient dynamics associated with time lags in returning to the unfished state following reserve implementation make that proxy inaccurate on short time scales. We assessed density ratio management rules using an age-structured, spatially explicit model of four US west coast nearshore fishes following reserve implementation, with scenarios encompassing sampling error, recruitment variability, and uncertainty in natural mortality. In deterministic simulations, management incorporating time lags generally resulted in a higher mean and lower variability in biomass over 20 years, but lower mean yield compared to management that did not. However, when stochastic recruitment was included, differences among simulations due to stochasticity were much greater than any difference in performance between management strategies. Nonetheless, in certain cases, accounting for time lags could help avoid unwarranted increases in harvest effort after reserve implementation.

Employees’ Perspectives on the Costs and Benefits of Organizations’ Environmental Initiatives

Employee participation is essential to organizations’ corporate social responsibility (CSR)-related environmental initiatives (EIs). Employees’ attitudes to participating in pro-environmental behaviors are addressed in workplace literature drawing upon the theory of planned behavior. However, antecedents to employees’ attitude formation, including perceptions of the costs and benefits of participating in EIs, have not been adequately researched. Greater understanding of EI attitude formation can support efforts to foster EI participation. This study explores employees’ perceptions of EI costs and benefits to employees personally, to their organization, and to society by applying goal framing theory. A sample of 120 survey participants described 150 initiatives and identified personal, organizational, and societal costs and benefits of the EIs. Cost and benefit categories are presented along with a taxonomy and themes. The findings of this study provide a reference point for researchers and managers in understanding how employees view EIs and how employees might be encouraged to participate.

“Sport and Anatomy”: Teaching, Research, and Assistance at the University of Pisa

Introduction: Over the last decades, the university system has experienced huge growth, facing several challenges. Accordingly, the University of Pisa recognizes the value and opportunities deriving from research and fully supports collaboration with the world of entrepreneurship and industry, as well as local communities. Study programs, teaching methods and technologies, learning environments, quality assurance, programmed student numbers, and research results are key features of the prestige of the scientific community. Aim: In this respect, “Sport and Anatomy”, a brand that includes an academic organization at the University of Pisa, holds two main goals: (i) to offer the top level in both educational and professional fields; and (ii) to optimize the fine-tuning among all these sections, thus becoming a reference point for sports management. Methods and results: Indispensable links between basic and specialist sciences through different Masters’ and schools were created. In addition to didactic activity, research activity, medical assistance, and rehabilitation were coordinated. Two main outcomes emerged from this experience: (i) improved stakeholder performances and (ii) optimized cooperation between university and local communities. Conclusions: “Sport and Anatomy” plays a key role in supervising and accomplishing in an innovative way all the three missions of the university (i.e., teaching, research, and dissemination of knowledge), thus strongly fulfilling the aims of modern university targets.