Ecosystem-based Fisheries Management Research Articles

Direct and ancillary benefits of ecosystem-based fisheries management in forage fish fisheries.

Natural resource management is evolving toward holistic, ecosystem‐based approaches to decision making. The ecosystem science underpinning these approaches needs to account for the complexity of multiple interacting components within and across coupled natural–human systems. In this research, we investigate the potential economic and ecological gains from adopting ecosystem‐based approaches for the sardine and anchovy fisheries off of the coast of California, USA. Research has shown that while predators in this system are likely substituting one forage species for another, the assemblage of sardine and anchovy can be a significant driver of predator populations. Currently, the harvest control rules for sardine and anchovy fisheries align more with traditional single species framework. We ask what are the economic and ecological gains when jointly determining the harvest control rules for both forage fish stocks and their predators relative to the status quo? What are the implications of synchronous and anti‐synchronous environmental recruitment variation between the anchovy and sardine stocks on optimal food‐web management? To investigate these questions, we develop an economic‐ecological model for sardine, anchovy, a harvested predator (halibut), and an endangered predator (Brown Pelican) that includes recruitment variability over time driven by changing environmental conditions. Utilizing large‐scale numerical optimal control methods, we investigate how the multiple variants of integrated management of sardine, anchovy, and halibut impact the overall economic condition of the fisheries and Brown Pelican populations over time. We find significant gains in moving to integrated catch control rules both in terms of the economic gains of the fished stocks, and in terms of the impacts on the Brown Pelican populations. We also compare the relative performance of current stylized catch control rules to optimal single species and optimal ecosystem‐based fisheries management (EBFM) across ecological and economic dimensions, where the former trade‐off considerable economic value for ecological goals. More generally, we demonstrate how EBFM approaches introduce and integrate additional management levers for policymakers to achieve non‐fishery objectives at lowest costs to the fishing sectors.

Ecosystem-based fisheries management is attainable, affordable, and should be viewed as a long-term commitment: Experiences from Lake Vättern, Sweden

Lake Vättern is Sweden’s second largest lake and faces multiple environmental challenges such as climate change, pollutants and invasive alien species. Since its foundation in 1957, the Lake Vättern Society of Water Conservation (LVSWC) has been a local actor aiming to manage a broad range of environmental issues concerning the lake and its catchment. Stakeholders can be members of LVSWC, which also organises a fisheries co-management group mainly dealing with fisheries issues. Ecosystem-based fisheries management (EBFM) is a widely desired framework shaped to focus on ecosystems, involve stakeholders, and address environmental issues in an adaptive, integrated and holistic manner while also including societal aspects. We have investigated how the management of Lake Vättern relates to 15 central principles for EBFM. The study found that LVSWC and the fisheries co-management group work along and towards the EBFM principles in a locally adapted way. Several environmental improvements have been observed concurrently with LVSWC activity, such as increased water clarity, and a strengthened stock of the Arctic char (Salvelinus alpinus). Long-term commitment by European, national and regional authorities was seen as essential to maintain and improve EBFM functions for Lake Vättern, to ensure continuity in the work, rather than having to depend on short projects. Becasue literature examples of EBFM in lakes are scarce worldwide, this study provides a unique example of the pursuit of EBFM in lake ecosystem management.

Identification Of Problems And Models Of Coastal Area Management Labuhan Village Sumbawa, District Labuhan Badas, Sumbawa

The coastal area of Labuhan Sumbawa Village has strategic value for economic development and improving people's welfare, but is very vulnerable to damage due to the use of multifunctional space, so that coastal management is urgently needed that focuses on regional characteristics, by placing three pillars of sustainable development, namely ecology, economy, and social. This study aims to identify problems and models of coastal area management in Labuhan Sumbawa Village, Labuhan Badas District, Sumbawa. The research method used is descriptive research method. Data was collected by means of observation and semi-structured interviews. Accidental sampling technique and qualitative data analysis. The results showed that in the coastal area of the research location, identified: (1) Physical damage to the environment, including: a) Damage to ecosystems (ecosystems, coral reefs, seagrass beds, and beaches); b) Damage to fish resources; c) Pollution; d) Abrasion, sedimentation, and siltation; and d) Natural disasters (floods); (2) Socio-economic problems, including: a) The problem of poverty and the low level of education of the population; b) Limited funds in development; and c) Lack of understanding of the value of coastal area resources; (3) Institutional problems, including: a) The problem of conflict of authority, which can occur due to sectoral development; b) The problem of legal uncertainty. The coastal area management models that can be applied are: (1) traditional management; (2) community-based coastal area resource management; (3) Co-management, and; (4) Ecosystem Based Fisheries Management (EBFM). The conclusion of the study is that damage to coastal areas will have an impact on ecological, economic, and social conditions so that multi-stakeholder involvement is very important in sustainable coastal area management. Keywords: Ecology, economy, social, coastal, model

STATUS OF FISHERIES MANAGEMENT WITH AN ECOSYSTEM APPROACH IN THE DOMAIN FISH RESOURCES FOR TERUBUK (Tenualosa macrura) IN BENGKALIS REGENCY, RIAU PROVINCE

This study aims as follows: 1) To determine the status of ecosystem-based fisheries management or Ecosystems Approach of Fisheries Management (EAFM) in the domain of fish resources for terubuk fish in Bengkalis Regency, Riau Province. The method used in this research is survey, observation and interview methods. The results of this study indicate that the indicators for the Composition of Catched Species and ETP Species of Fish Resources are still in good status. Meanwhile, indicators that need to be prioritized for improvement in sustainable fisheries management in the future because it is already in a moderate to bad status are Raw CPUE and Fish Size Trends. The conclusion of this research shows that fisheries management for terubuk fisheries (Tenualosa macrura) is still in good condition with green flag modeling and a mean value of 2,7.

The isotopic niche of Atlantic, biting marine mammals and its relationship to skull morphology and body size

Understanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

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.

Habitat Suitability Modeling for the Feeding Ground of Immature Albacore in the Southern Indian Ocean Using Satellite-Derived Sea Surface Temperature and Chlorophyll Data

In the current study, remotely sensed sea surface ocean temperature (SST) and sea surface chlorophyll (SSC), an indicator of tuna abundance, were used to determine the optimal feeding habitat zone of the southern Indian Ocean (SIO) albacore using a habitat suitability model applied to the 2000–2016 Taiwanese longline fishery data. The analysis showed a stronger correlation between the 2-month lag SSC and standardized catch per unit effort (CPUE) than 0-, 1-, 3-, and 4-month lag SSC. SST also exhibited a stronger correlation with standardized CPUE. Therefore, SST and SSC_2 were selected as final variables for model construction. An arithmetic mean model with SST and SSC_2 was deemed suitable to predict the albacore feeding habitat zone in the SIO. The preferred ranges of SSC_2 and SST for the feeding habitat of immature albacore were 0.07–0.09 mg m−3 and 16.5–18.5 °C, respectively, and mainly centralized at 17.5 °C SST and 0.08 mg m−3 SSC_2. The selected habitat suitability index model displayed a high correlation (R2 = 0.8276) with standardized CPUE. Overall, temperature and ocean chlorophyll were found to be essential for albacore habitat formation in the SIO, consistent with previous studies. The results of this study can contribute to ecosystem-based fisheries management in the SIO by providing insights into the habitat preference of immature albacore tuna in the SIO.

Research on Fishery Resource Assessment and Sustainable Utilization (FRASU) during 1990–2020: A bibliometric review

Fishery resource assessment and sustainable utilization (FRASU) is a topic of global concern. Although fishery resources are highly profitable, these are linked to environmental and socio-economic issues. In the context of increasing demand for fishery sustainability, fishery resource assessment is essential to support scientific fishery resource management. Bibliometric techniques and the Web of Science (WOS) database from 1990 to 2020 were employed to analyse the journals, authors, institutions, countries, cited references, and keywords using the CiteSpace (5.3. R11) software and standard bibliometric indicators. A quantitative review of global research related to FRASU identified recent important research topics and allowed prediction of research trends, as well as confirmed that it is an increasing area of concern. A total of 1631 publications were retrieved from 1990 to 2020, and the most active journals, countries, authors and institutions in the field were identified. 'Fisheries Research', 'Ocean Coastal Management' and 'ICES Journal of Marine Science' are the main journals that publish FRASU research. European and North American countries are the main publishers in this field, while the contribution of Asian countries has gradually increased. It is expected that China, Japan, Brazil, and India will make increasingly significant contributions to this field. Groupers, size, catch-per-unit-effort and genetic diversity are important core research areas in this field. Policy, maximum sustainable yield, small scale fisheries, ecosystem management and sustainability frameworks are identified as potential emerging research areas. Furthermore, five key areas of current research trends on FRASU were identified: problems with fishery resource assessment, impact of changes in marine biodiversity on ecosystem services, influence of fishery resource changes on the structure of food webs, ecosystem-based fishery management, and frameworks for sustainable development of fishery resources. The findings from this bibliometric study provide insight into in the growth of research publications and changes in hot areas in the field of FRASU over the past 30 years, including global trends in emerging areas of research.

Local Values and Data Empower Culturally Guided Ecosystem‐Based Fisheries Management of the Wuikinuxv Bear–Salmon–Human System

AbstractDespite numerous examples of ecosystem‐based fisheries management (EBFM) addressing tradeoffs between ecological and commercial fishery interests, local social and cultural concerns are less frequently considered. We illustrate how Indigenous fishery harvest goals and data from locally driven wildlife research can inform EBFM, guided by cultural values of respect for and reciprocity with wildlife. Grizzly bearsUrsus arctos horribilishold particular importance for the Wuikinuxv First Nation in Rivers Inlet, British Columbia, where people and bears have coexisted as consumers of Sockeye SalmonOncorhynchus nerkafor millennia. The region’s valuable commercial fishery, active since the late 1800s, has been closed since the Sockeye Salmon population collapsed in the mid‐1990s, but the Wuikinuxv maintain a modest food, social, and ceremonial (FSC) harvest. To address questions about balancing the needs of fishers and ecosystem recipients, we quantified tradeoffs between long‐term maximum sustainable fishery yield and ecosystem benefits (for which bear density served as a proxy). We fitted age‐structured state‐space spawner–recruitment models and estimated relationships among spawner abundance, long‐term fishery yields, and relative bear densities in time periods before and after the population collapse. We found that predicted maximum postcollapse bear density was 74% of maximum precollapse densities. We estimated a 94% decline in Sockeye Salmon equilibrium population size (from ˜3,115,000 to 200,000), resulting in a commensurate decline in maximum sustainable fishery yield. Despite this, we showed that Wuikinuxv FSC harvest goals are compatible with an EBFM target that seeks also to sustain relatively high bear densities, whereby relative fishery yield and bear density are reduced about 10% from their respective maxima, assuming that current Sockeye Salmon productivity and carrying capacity remain similar for the foreseeable future, although these estimates are highly uncertain. Collectively, our findings illustrate how EBFM can apply interdisciplinary approaches that draw not only on fisheries ecology but also local values to design sustainable harvest strategies for diverse beneficiaries.

Ecological considerations for species distribution modelling of euphausiids in the Northeast Pacific Ocean

Euphausiids are a keystone species in marine food webs of the Northeast Pacific Ocean, important for forage fish, commercial fish species and marine predators such as seabirds and whales. Ecosystem-based fisheries management relies on realistic lower-trophic-level information for forecasting under future changing climate scenarios. We synthesised information from quantitative modelling studies analysing the relationship between euphausiids and their environment for two species of euphausiids that dominate assemblages in this region — Euphausia pacifica and Thysanoessa spinifera. Studies analysed suggest that variables reflecting the physical and biological environment in situ, features reflecting the geomorphic marine landscape, and large-scale climate indices all significantly affect euphausiid biomass and distribution. Temperature was the most tested predictor variable in the euphausiid models reviewed; however, it was significant in fewer models than other variables tested. We review and compare model structures, predictor variable selection and temporal lag phases to develop recommendations for species distribution modelling of euphausiids in the Northeast Pacific Ocean. We believe the results from this review will be applicable globally across regions with similar climates where euphausiids are numerous and can be adapted for different species and environments.

A Case Study in Connecting Fisheries Management Challenges With Models and Analysis to Support Ecosystem-Based Management in the California Current Ecosystem

One of the significant challenges to using information and ideas generated through ecosystem models and analyses for ecosystem-based fisheries management is the disconnect between modeling and management needs. Here we present a case study from the U.S. West Coast, the stakeholder review of NOAA’s annual ecosystem status report for the California Current Ecosystem established by the Pacific Fisheries Management Council’s Fisheries Ecosystem Plan, showcasing a process to identify management priorities that require information from ecosystem models and analyses. We then assess potential ecosystem models and analyses that could help address the identified policy concerns. We screened stakeholder comments and found 17 comments highlighting the need for ecosystem-level synthesis. Policy needs for ecosystem science included: (1) assessment of how the environment affects productivity of target species to improve forecasts of biomass and reference points required for setting harvest limits, (2) assessment of shifts in the spatial distribution of target stocks and protected species to anticipate changes in availability and the potential for interactions between target and protected species, (3) identification of trophic interactions to better assess tradeoffs in the management of forage species between the diet needs of dependent predators, the resilience of fishing communities, and maintenance of the forage species themselves, and (4) synthesis of how the environment affects efficiency and profitability in fishing communities, either directly via extreme events (e.g., storms) or indirectly via climate-driven changes in target species availability. We conclude by exemplifying an existing management process established on the U.S. West Coast that could be used to enable the structured, iterative, and interactive communication between managers, stakeholders, and modelers that is key to refining existing ecosystem models and analyses for management use.

Examining the expansion of qualitative network models towards integrating multifaceted human dimensions

Abstract Qualitative network models (QNMs) have become a popular tool to assess how ecosystems respond to a perturbation within ecosystem-based fisheries management strategies. Yet, the incorporation of humans into these models is often rudimentary, potentially limiting the accuracy and reliability of the model results. We developed QNMs focusing solely on the social components, derived from content analysis of the literature on the effects of the US Pacific halibut Individual Fishing Quota (IFQ) Program and evaluated how the QNMs performed with respect to simulating the programmatic effects on individual well-being components. The QNMs were effective at reproducing IFQ programmatic effects and demonstrating how well-being heterogeneity across user groups can be incorporated into network models. However, key mechanistic variables were omitted to maintain model stability, reducing our ability to fully replicate the IFQ system. We conclude that QNMs require improvement to incorporate human dimensions that reflect broader social realities. Yet, given the current structural limitations of these modelling frameworks coupled with the complexity of human decision making, there are likely to be continued issues with integrating humans accurately and representatively into these models.

Modeling impacts of invasive sharp tooth African catfish Clarias gariepinus (Burchell 1822) and Mozambique tilapia Oreochromis mossambicus (Peters, 1852) on the ecosystem of a tropical reservoir ecosystem in India.

Invasive species exert a strong impact on the trophic structure and functioning of the ecosystem they occupy. A modeling software globally used to assess these impacts is Ecopath with Ecosim. This study measures the effects of two invasive species, African catfish Clarias gariepinus, in the food web of the Karapuzha reservoir ecosystem in India. The findings show that the two invasive species directly and indirectly influence several ecosystem elements. The high level of niche overlap (92%) and strong competition for similar resources was exhibited by C. gariepinus. The adverse effects of African catfish on all fish and crustaceans in the reservoir were revealed by mixed trophic impact. Oreochromis mossambicus impacts were both positive and negative. It had a beneficial impact on its predator aquatic birds and was negative towards minnows. This study will help fishery managers to make informed decisions for ecosystem-based fishery management of fish resources.

Linking Fishing Behavior and Ecosystem Dynamics Using Social and Ecological Network Models

One goal of ecosystem-based management is studying an ecosystem and its people, the socio-ecological system, in a qualitative and quantitative modeling approach that can provide management agencies with possible outcomes of their actions using scenario forecasting. Ecosystem-based fisheries management strives to use the socio-ecological system approach, including direct and indirect impacts on multiple species including the behavioral responses of fishers after a regulatory change (a gillnet ban). Here, we link fisher behavioral networks with a mass-balanced food-web ECOPATH network model of an estuarine ecosystem and its commercial fisheries for an analysis of fishing impacts after a gillnet ban on multiple species using ECOSIM. We modeled fisher behavioral networks using reported catches of species from individual fishers along with the gear fished to create nodes in a gear/species affiliation network. Individual fishers with common gear/species use are indicative of common fishing behavior. When such fishers have high network centrality and are engaged in multiple gear/species fisheries, they can transition to other gear/species fisheries along “switching pathways” when facing a regulatory change. We used an index of joint gear participation to identify likely gear switching pathways, and we predicted changes in fishing effort after a gill net ban. We simulated the gill net ban in ECOSIM under two scenarios of fishing effort: Scenario 1, gill net fishing effort of 0%; Scenario 2, gill net fishing effort of 0% with increased effort in the alternative gear fisheries using the predicted switching pathways for the affiliation network. Scenario 1 predicted an increase in flounder (Paralichthys spp.) biomass over a decade. Under Scenario 2, fishers targeting flounders were predicted to switch from gill nets to pound nets. Scenario 2 predicted a 7% decline in flounder biomass over ten years, rather than an increase in flounders. The gillnet ban with increased effort due to switching is predicted to have the opposite effect on the conservation goal, which was to increase flounder stocks. Fishery management that incorporates a socio-ecological approach modeling both fisher behaviors and multi-species ecosystem responses can reveal single-species responses that are in the opposite direction of the anticipated management goals.

A multispecies size-structured matrix model incorporating seasonal dynamics

Multi-species size spectrum models (MSSMs) have been widely used to investigate and understand the dynamics of marine communities impacted by fishing and environmental changes to support ecosystem-based fisheries management. The continuous nature of the modelled processes makes it challenging to incorporate periodic biological processes and discontinuous life-history traits into MSSMs; therefore, a discrete multi-species model is needed. We developed a new size-structured matrix model with discrete processes to describe multi-species interactions and energy flows through predation, reproduction, metabolism, and mortality in matrix forms. A framework for assessing the population-level consequences of capital and income breeding strategies was developed, with seasonal properties. Preliminary investigations were conducted on a theoretical community comprising eight interacting species with different reproductive strategies. The utility of our model was demonstrated by showing emergent properties in the seasonal dynamics of marine communities and life-history traits such as survival, growth, and reproduction of capital and income breeders. The model enabled exploration of population dynamics caused by migration at the ecosystem level. An example application of the model in marine protected areas (MPAs), where species undertook seasonal spawning migrations, indicated that the size of MPAs may affect their potential conservation and economic benefits to fisheries. This model has the potential to unravel the relationships between drivers and seasonal dynamics and to assess the effectiveness of fisheries management strategies such as seasonal closure of fishing.

International politics must be considered together with climate and fisheries regulation as a driver of marine ecosystems

Seafood is an essential source of protein globally. As its demand continues to rise, balancing food security and the health of marine ecosystems has become a pressing challenge. Ecosystem-based fisheries management (EBFM) has been adopted by the European Union (EU) Common Fisheries Policy (CFP) to meet this challenge by accounting for the multiple interacting natural and socio-economic drivers. The CFP includes both the implementation of regulatory measures to EU stocks and the establishment of bilateral fisheries agreements with neighbouring countries, known as sustainable fisheries partnership agreements (SFPAs). While the effects of fisheries management regulations are well acknowledged, the consequences of the SFPAs on EU ecosystems have been commonly overlooked. Here we investigate the development of the Gulf of Cadiz marine ecosystem over the last two decades and found evidence of the impact of both policy interventions. Our findings reveal the effectiveness of regulatory measures in reverting a progressively degrading ecosystem, characterised by high fishing pressure and dominance of opportunistic species, to a more stable configuration, characterised by higher biomass of small pelagics and top predators after 2005. Knock-on effects of the EU-Morocco SFPA and climate effects were detected before 2005, resulting in increased purse seine fishing effort, lower biomass of pelagic species and warmer temperatures. This southern EU marine ecosystem has been one of the latest to introduce regulations and is very exposed to fishery agreements with neighbouring Morocco. Our study highlights the importance of taking into consideration, not only the effects of in situ fisheries regulations but also the indirect implications of political agreements in the framework of EBFM.

The Path to an Ecosystem Approach for Forage Fish Management: A Case Study of Atlantic Menhaden

Atlantic menhaden (Brevoortia tyrannus) support the largest fishery by volume on the United States East Coast, while also playing an important role as a forage species. Managers’ and stakeholders’ increasing concerns about the impact of Atlantic menhaden harvest on ecosystem processes led to an evolution in the assessment and management of this species from a purely single-species approach to an ecosystem approach. The first coastwide stock assessment of Atlantic menhaden for management used a single-species virtual population analysis (VPA). Subsequent assessments used a forward projecting statistical catch-at-age framework that incorporated estimates of predation mortality from a multispecies VPA while analytical efforts continued toward the development of ecosystem models and explicit ecological reference points (ERPs) for Atlantic menhaden. As an interim step while ecosystem models were being developed, a series of ad hoc measures to preserve Atlantic menhaden biomass for predators were used by managers. In August 2020, the Atlantic States Marine Fisheries Commission formally adopted an ecological modeling framework as a tool to set reference points and harvest limits for the Atlantic menhaden that considers their role as a forage fish. This is the first example of a quantitative ecosystem approach to setting reference points on the United States Atlantic Coast and it represents a significant advance for forage fish management. This case study reviews the history of Atlantic menhaden stock assessments and management, outlines the progress on the current implementation of ERPs for this species, and highlights future research and management needs to improve and expand ecosystem-based fisheries management.

Variation in predator diet and prey size affects perceived impacts to salmon species of high conservation concern

Management of protected species is difficult when objectives include the recovery of both predator and its prey. Ideally, identifying trade-offs between competing objectives involves evaluating management alternatives with a quantitative model that integrates information on both species, but data are often limited. We used new predator diet data and simulation modeling to update our understanding of seal predation on juvenile Chinook (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) in the Puget Sound. Under prey size assumptions used by previous studies, estimates suggest predation could be a significant source of mortality for Chinook salmon (mean: 37% of ocean age-0 juveniles), but varied considerably among years (range of median estimates: 22%–49%). However, when we estimated prey size from otoliths recovered from seal scats, the impact (numbers of fish consumed) decreased by 71%. Predation on coho salmon was estimated to be relatively low under both scenarios (6%–8% of ocean age-0 juveniles) with a 21% decrease in consumption using otolith-derived prey size. Our analysis highlights the importance of updating model inputs and re-evaluating assumptions of multi-species models used for ecosystem-based fisheries management.

Appraising the Status of Fish Community Structure in the Yellow Sea Based on an Indicator-Testing Framework

Fish community structure (FCS) of the Yellow Sea (YS) is affected by multiple pressures. Quantifying the responses of indicators of FCS (IFCSs) to pressures is a key aspect of ecosystem-based fisheries management. Quantitative methodology has hitherto been rarely applied to evaluate the performance of ecological indicators in response to physical and anthropogenic pressures and management actions. In this study, we adopted a quantitative and flexible framework to quantify the performance of IFCSs in the YS as well as to identify a suite of operational IFCSs to evaluate the status of the FCS via two state-space approaches. A total of 22 IFCSs were tested for their responses to three types of pressures including anthropogenic activities (fishing), large-scale climate change, and regional environmental variables. Our results indicate that the majority of IFCSs have good performance in terms of sensitivity in their responses to pressures, but weak performance in terms of robustness. The IFCSs tend to respond stronger to fishing than to large-scale climatic indices and regional environmental indices both in terms of sensitivity and robustness. A final indicator suite of five best-performing IFCSs was identified. The five IFCSs include total catch (ToC), mean trophic level (MTL), the ratio of catch of large predatory groups to total catch (LPC/ToC), mean temperature of catch (MTC) [or alternatively catch of small pelagic groups (SPC)], and functional evenness based on thermal groups (T-J′FD), all of which show regime shift patterns consistent with climate change. Compared to a reference period (1960–1964), the status of the current FCS has been obviously changed, and the long-term trajectories of the final indicator suite is consistent with that of fishing pressure. This study demonstrates the applicability of the indicator-testing framework in appraising the status of FCS, and facilitates moving towards ecosystem-based fisheries management in the YS.

Integrating multi-disciplinary data sources relating to inshore fisheries management via a Bayesian network

The move towards broader management of marine ecosystems has received significant momentum in recent years. Fundamental to Ecosystem-Based Management (EBM) and Ecosystem-Based Fisheries management (EBFM) is the need to engage relevant stakeholder groups. Here we present a Bayesian network (BN) tool developed to describe the snapper population in the Hauraki Gulf, New Zealand, and investigate possible outcomes of alternative management scenarios on snapper abundance. The Hauraki Gulf is a location where the marine environment is both highly valued and in high demand for the goods and services it provides. Snapper are a key component of this social–ecological system. We developed a BN focussed on key snapper life stages, and the consequences of stressors, including fishing, uses of marine space, land use practises (which influence sediment and nutrient yield), biogenic and environmental habitat variables, and upper level drivers such as climate change, human population growth and the global economy. Parameters were populated through a range of information types, from empirical and model analysis to literature review and expert opinion. Parameters for the core of the BN model (i.e. the snapper life stages and fishing methods) were adjusted so that the predicted effects of fishing reflected those seen in model projections from an age structured population model that had recently been used to inform the management of the snapper population in the Hauraki Gulf. The two most influential factors within this BN were fishing and land–use practises. Although there was a strong impact on snapper populations from land–use practises and resulting sedimentation that detrimentally affects biogenic habitats that juvenile snapper depend on, the potential impact of fishery extraction was much stronger. While fishery extraction of snapper is generally well managed, under the existing management set up it is also the only major stressor that would likely be regulated in response to decreases in the snapper population (regardless of the source of any impact). Engaging stakeholders to address issues such as this remains the greatest challenge facing EBFM/EBM in the Hauraki Gulf, but may be possible with tools such as the BN presented here.