scholarly journals Incorporating Stakeholder Knowledge into a Complex Stock Assessment Model: The Case of Eel Recruitment

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1136
Author(s):  
Hilaire Drouineau ◽  
Marie Vanacker ◽  
Estibaliz Diaz ◽  
Maria Mateo ◽  
Maria Korta ◽  
...  
Keyword(s):  
Western Europe ◽  
Fishery Management ◽  
Stock Assessment ◽  
Assessment Model ◽  
Complex Life Cycle ◽  
European Eel ◽  
Species Management ◽  
Complex Models ◽  
Prior Construction ◽  
Multiple Actors

Mistrust between scientists and non-scientist stakeholders is a key challenge in fishery management. The support of management with complex models is difficult, as these models cannot easily communicate their results to end users, resulting in a lack of confidence. As an example, the complex life cycle of the European eel raises problems of coordination and discussion among the multiple actors involved in the species’ management. The GEREM model has been proposed as a tool for estimating recruitment, but its complexity, which is essential for addressing the characteristics of the species, makes it difficult to understand and accept by all stakeholders. In the context of the SUDOANG project, we proposed a co-parametrisation of this assessment model to tackle this mistrust. Through the use of various questionnaires, stakeholders were involved in two important choices for the model (zone definition and prior construction). Regular workshops and presentations were organised to explain the model rationales and to gather feedback and expectations. The results show that stakeholders have very similar perceptions of the potential definitions of sub-areas of recruitment in south-western Europe, and these perceptions are consistent with the underlying environmental conditions. On the other hand, the stakeholders have contrasting opinions about the exploitation rates of fisheries in different river basins, and the use of their knowledge currently has little effect on GEREM estimates. More importantly, the overall approach of this study is thought to have reconstructed the trust and confidence among participants.

scholarly journals Incorporating Stakeholder Knowledge Into a Complex Stock Assessment Model, the Case of Eel Recruitment

2021 ◽  
Author(s):  
Hilaire Drouineau ◽  
Vanacker Marie ◽  
Estibaliz Diaz ◽  
Mateo Santos Maria ◽  
Korta Maria ◽  
...  
Keyword(s):  
Western Europe ◽  
Fishery Management ◽  
Stock Assessment ◽  
Assessment Model ◽  
The Other ◽  
Complex Life Cycle ◽  
European Eel ◽  
Complex Models ◽  
Prior Construction ◽  
Multiple Actors

Mistrust between scientists and non-scientist stakeholders is a key challenge in fishery management. This problem is exacerbated with the use of complex models to support management: these models suffer from difficulties in communicating their results and a lack of confidence from end users. The European eel is an illustrative example; its complex life cycle raises problems of coordination and discussion among the multiple actors involved in the management of the species. The GEREM model has been proposed as a tool for estimating recruitment, but its complexity, which is essential for addressing the characteristics of the species, makes it difficult to understand and accept by all stakeholders. In the context of the SUDOANG project, we proposed a co-parametrization of this assessment model to tackle this mistrust. Through the use of various questionnaires and appropriate statistical analyses, stakeholders were involved in two important choices for the model (zone definition and prior construction). Regular workshops and presentations were organised to explain the model rationales and to gather feedback and expectations. The results show that stakeholders have very similar perceptions of the potential definitions of sub-areas of recruitment in south-western Europe, and these perceptions are consistent with the underlying environmental conditions. On the other hand, the stakeholders have contrasting opinions about the exploitation rates of fisheries in different river basins, and the use of their knowledge currently has little effect on GEREM estimates. More importantly, the overall approach of this study is thought to have reconstructed the trust and confidence among participants.

scholarly journals Ecological Reference Points for Atlantic Menhaden Established Using an Ecosystem Model of Intermediate Complexity

2020 ◽  
Vol 7 ◽  
Author(s):  
David Chagaris ◽  
Katie Drew ◽  
Amy Schueller ◽  
Matt Cieri ◽  
Joana Brito ◽  
...  
Keyword(s):  
Striped Bass ◽  
Fishery Management ◽  
Stock Assessment ◽  
Reference Points ◽  
Atlantic Menhaden ◽  
Assessment Model ◽  
Total Allowable Catch ◽  
Important Species ◽  
Ecosystem Impacts ◽  
Intermediate Complexity

Atlantic menhaden (Brevoortia tyrannus) are an important forage fish for many predators, and they also support the largest commercial fishery by weight on the U.S. East Coast. Menhaden management has been working toward ecological reference points (ERPs) that account for menhaden’s role in the ecosystem. The goal of this work was to develop menhaden ERPs using ecosystem models. An existing Ecopath with Ecosim model of the Northwest Atlantic Continental Shelf (NWACS) was reduced in complexity from 61 to 17 species/functional groups. The new NWACS model of intermediate complexity for ecosystems (NWACS-MICE) serves to link the dynamics of menhaden with key managed predators. Striped bass (Morone saxatilis) were determined to be most sensitive to menhaden harvest and therefore served as an indicator of ecosystem impacts. ERPs were based on the tradeoff relationship between the equilibrium biomass of striped bass and menhaden fishing mortality (F). The ERPs were defined as the menhaden F rates that maintain striped bass at their biomass target and threshold when striped bass are fished at their Ftarget, and all other modeled species were fished at status quo levels. These correspond to an ERP Ftarget of 0.19 and an ERP Fthreshold of 0.57, which are lower than the single species reference points by 30–40%, but higher than current (2017) menhaden F. The ERPs were then fed back into the age-structured stock assessment model projections to provide information on total allowable catch. The ERPs developed in this study were adopted by the Atlantic menhaden Management Board, marking a shift toward ecosystem-based fishery management for this economically and ecologically important species.

scholarly journals Evaluating the role of data quality when sharing information in hierarchical multistock assessment models, with an application to Dover sole

2019 ◽  
Vol 76 (10) ◽  
pp. 1819-1835
Author(s):  
Samuel D.N. Johnson ◽  
Sean P. Cox
Keyword(s):  
Statistical Power ◽  
Fishery Management ◽  
Stock Assessment ◽  
Simulated Data ◽  
Assessment Model ◽  
Production Model ◽  
Estimation Errors ◽  
Lower Estimation ◽  
Relative Errors ◽  
Dover Sole

An emerging approach to data-limited fisheries stock assessment uses hierarchical multistock assessment models to group stocks together, sharing information from data-rich to data-poor stocks. In this paper, we simulate data-rich and data-poor fishery and survey data scenarios for a complex of Dover sole (Microstomus pacificus) stocks. Simulated data for individual stocks were used to compare estimation performance for single-stock and hierarchical multistock versions of a Schaefer production model. The single-stock and best-performing multistock models were then used in stock assessments for the real Dover sole data. Multistock models often had lower estimation errors than single-stock models when assessment data had low statistical power. Relative errors for productivity and relative biomass parameters were lower for multistock assessment model configurations. In addition, multistock models that estimated hierarchical priors for survey catchability performed the best under data-poor scenarios. We conclude that hierarchical multistock assessment models are useful for data-limited stocks and could provide a more flexible alternative to data pooling and catch-only methods; however, these models are subject to nonlinear side effects of parameter shrinkage. Therefore, we recommend testing hierarchical multistock models in closed-loop simulations before application to real fishery management systems.

scholarly journals Can spawning origin information of catch or a recruitment penalty improve assessment and fishery management performance for a spatially structured stock assessment model?

2018 ◽  
Vol 75 (12) ◽  
pp. 2136-2148 ◽  
Author(s):  
Yang Li ◽  
James R. Bence ◽  
Travis O. Brenden
Keyword(s):  
Fishery Management ◽  
Stock Assessment ◽  
Mortality Rates ◽  
Assessment Model ◽  
Biomass Estimation ◽  
Management Performance ◽  
Population Mixing ◽  
Standard Assessment ◽  
Stock Biomass ◽  
Spawning Stock

We used simulations based on lake whitefish (Coregonus clupeaformis) populations to explore the benefits of using spawning origin information for parsing catch to spawning populations in stock assessments for intermixed fisheries exhibiting an overlapping movement strategy. We compared this origin-informed assessment model with a standard assessment model that did not parse catch. We additionally evaluated the influence of including annual recruitment penalties. For standard assessment models, spawning stock biomass estimates could be unstable and biased (sometimes by more than 50%), depending upon population mixing and productivity, and in some cases estimated near average zero recruitment in the terminal year. Incorporating information on population-specific harvest age composition improved spawning stock biomass estimation (e.g., by sometimes essentially removing 50% biases and improving accuracy). Assessments with recruitment penalties produced less biased terminal recruitment estimates (sometimes a 100% bias was removed). Under status quo target mortality rates, improvements in assessments did not necessarily translate to improved fishery management performance (e.g., avoiding depletion of spawning biomass), but such improvements, and overall better performance, were seen at lower target mortality rates.

scholarly journals Stock assessment and projections incorporating discard estimates in some years: an application to the hake stock in ICES Divisions VIIIc and IXa

2010 ◽  
Vol 67 (6) ◽  
pp. 1185-1197 ◽  
Author(s):  
C. Fernández ◽  
S. Cerviño ◽  
N. Pérez ◽  
E. Jardim
Keyword(s):  
Time Series ◽  
Stock Assessment ◽  
Reference Points ◽  
Assessment Model ◽  
Marine Science ◽  
Fishing Mortality ◽  
Change Over Time ◽  
Age Structured ◽  
Available Information ◽  
Over Time

Abstract Fernández, C., Cerviño, S., Pérez, N., and Jardim, E. 2010. Stock assessment and projections incorporating discard estimates in some years: an application to the hake stock in ICES Divisions VIIIc and IXa. – ICES Journal of Marine Science, 67: 1185–1197. A Bayesian age-structured stock assessment model is developed to take into account available information on discards and to handle gaps in the time-series of discard estimates. The model incorporates mortality attributable to discarding, and appropriate assumptions about how this mortality may change over time are made. The result is a stock assessment that accounts for information on discards while, at the same time, producing a complete time-series of discard estimates. The method is applied to the hake stock in ICES Divisions VIIIc and IXa, for which the available data indicate that some 60% of the individuals caught are discarded. The stock is fished by Spain and Portugal, and for each country, there are discard estimates for recent years only. Moreover, the years for which Portuguese estimates are available are only a subset of those with Spanish estimates. Two runs of the model are performed; one assuming zero discards and another incorporating discards. When discards are incorporated, estimated recruitment and fishing mortality for young (discarded) ages increase, resulting in lower values of the biological reference points Fmax and F0.1 and, generally, more optimistic future stock trajectories under F-reduction scenarios.

scholarly journals Correcting density-dependent effects in abundance estimates from bottom-trawl surveys

2014 ◽  
Vol 71 (5) ◽  
pp. 1107-1116 ◽  
Author(s):  
Stan Kotwicki ◽  
James N. Ianelli ◽  
André E. Punt
Keyword(s):  
Stock Assessment ◽  
Dead Zone ◽  
Walleye Pollock ◽  
Assessment Model ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Negative Consequences ◽  
Catch Per Unit Effort ◽  
Density Dependent ◽  
Index Of Abundance

Abstract Indices of abundance are important for estimating population trends in stock assessment and ideally should be based on fishery-independent surveys to avoid problems associated with the hyperstability of the commercial catch per unit effort (cpue) data. However, recent studies indicate that the efficiency of the survey bottom trawl (BT) for some species can be density-dependent, which could affect the reliability of survey-derived indices of abundance. A function qe∼f(u), where qe is the BT efficiency and u the catch rate, was derived using experimentally derived acoustic dead-zone correction and BT efficiency parameters obtained from combining a subset of BT catch data with synchronously collected acoustic data from walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS). We found that qe decreased with increasing BT catches resulting in hyperstability of the index of abundance derived from BT survey. Density-dependent qe resulted in spatially and temporarily variable bias in survey cpue and biased population age structure derived from survey data. We used the relationship qe∼f(u) to correct the EBS trawl survey index of abundance for density-dependence. We also obtained a variance–covariance matrix for a new index that accounted for sampling variability and the uncertainty associated with the qe. We found that incorporating estimates of the new index of abundance changed outputs from the walleye pollock stock assessment model. Although changes were minor, we advocate incorporating estimates of density-dependent qe into the walleye pollock stock assessment as a precautionary measure that should be undertaken to avoid negative consequences of the density-dependent qe.

scholarly journals Conceptual Readings into the Cold War: Towards Transnational Approaches from the Perspective of Latin American Studies in Eastern and Western Europe

2017 ◽  
Vol 30 (60) ◽  
pp. 203-218 ◽  
Author(s):  
Albert Manke ◽  
Kateřina Březinová ◽  
Laurin Blecha
Keyword(s):  
Cold War ◽  
Latin American ◽  
Western Europe ◽  
Global South ◽  
Latin American Studies ◽  
Global North ◽  
Scale Integration ◽  
The Cold War ◽  
Eastern And Western Europe ◽  
Multiple Actors

Abstract This bibliographical and conceptual essay summarizes recent research in Cold War Studies in Europe and the Americas, especially on smaller states in historiographical studies. Against the background of an increasing connectedness and globalization of research about the Cold War, the authors highlight the importance of the full-scale integration of countries and regions of the 'Global South' into Cold War Studies. Critical readings of the newly available resources reveal the existence of important decentralizing perspectives resulting from Cold War entanglements of the 'Global South' with the 'Global North.' As a result, the idea that these state actors from the former 'periphery' of the Cold War should be considered as passive recipients of superpower politics seems rather troubled. The evidence shows (at least partially) autonomous and active multiple actors.

scholarly journals Lobster Fishery Connectivity and Management in Indonesia Waters

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Waluyo Waluyo ◽  
Taslim Arifin
Keyword(s):  
Genetic Structure ◽  
Fishery Management ◽  
Marine Organism ◽  
Molecular Genetic ◽  
Three Dimensional ◽  
Geographical Information ◽  
Biophysical Model ◽  
Complex Life Cycle ◽  
Biophysical Modeling ◽  
The Individual

The distribution of lobsters in Indonesia waters is very wide, even lobster species in Indonesia are also scattered in the tropical waters of the western Pacific Ocean, the Indian Ocean, Africa to Japanese waters.Indonesia waters are divided into 11 (eleven) Fishery Management Zone (FMZ). Lobsters in Indonesia may come from various water areas, both national and regional waters zone, it’s called the sink population, its spread is influenced by the movement of the current. Lobster seed is nurtured by nature through oceancurrents from Australia, East Indonesia, Japan, then back to Australia. Lobsters have a complex life cycle,where adult lobsters inhabit coral reefs as a place to lay eggs, then hatch into planktonic larvae, and grow up in open seas and carry out diurnal and ontogenetic vertical migrations before returning to nurseries in shallow coastal areas and reefs. coral, as well as habitat by the type of species. Literature research had used at leasttwo methodologies to estimate the distribution and connection sensitivity matrices of marine organism larvae.The two most common approaches are using genetic markers and numerical biophysical modeling. Thus, this research uses molecular genetic techniques to explain the genetic structure of lobster populations using a biophysical model approach that can explain the genetic structure of lobsters, as well as the distribution base on regional oceanographic synthesis data and lobster biology known in Indonesia waters. This model has four components, namely: 1) a benthic module based on a Geographical Information System (GIS) which is a lobster habitat in the spawning and recruitment process, 2) a physical oceanography module containing daily velocity in the form of a three-dimensional hydrodynamic model, 3) a larva biology module that describes larval life history characteristics, and 4) a Lagrangian Stochastic module that tracks the individual trajectories of larvae.

Age-based stock assessment of the European eel (Anguilla anguilla) is heavily biased by stocking of unmarked farmed eels

2018 ◽  
Vol 208 ◽  
pp. 258-266 ◽  
Author(s):  
Björn Kullmann ◽  
Jan-Dag Pohlmann ◽  
Marko Freese ◽  
Alexander Keth ◽  
Laura Wichmann ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Anguilla Anguilla ◽  
European Eel
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