Dorleta Garcia

AZTI · Marine Research Division

This study tackles the challenges of providing advice for fishing EU demersal stocks when based solely on single-species data and Total Allowable Catches. Such advice neglects intricate multi-species interactions and could result in the over-exploitation of more vulnerable stocks. In this study, we explore ‘mixed fisheries’, a concept developed wit...

The age‐structured assessment model available in the MSEtool R package assesses stock status and exploitation for varying data availability, from limited to rich datasets. We investigated model accuracy in relation to data availability, population exploitation levels, initial population assumption and fishery selectivity misspecification. Estimates...

Mesopelagic fish are considered a possible future fisheries resource, but the biological sustainability of their potential exploitation has not yet been assessed. Sustainability should be evaluated at the population level, for which accurate stock-specific life-history parameters are required. Here, we use a length-based model to estimate life-hist...

European hake Merluccius merluccius is a commercially important fish species that is known to have a marked bathymetric preference. No other environmental variable has yet been identified to drive the distribution of hake. This study looked into different climatic variables at different depths and identified sea bottom temperature, sea bottom disso...

Maurolicus muelleri is a significant component of the marine ecosystem and has the potential to be a valuable fishery resource. However, in the Bay of Biscay, its primary biological traits remain unclear. This study presents data on the length distribution, age, growth, maturity ogive, spawning season, batch fecundity, and sex ratio for Maurolicus...

The European Commission tendered the study “Marine Biodiversity Modelling” [RTD/2021/MV/10] to pursue the identification and characterization of a subset of candidate biodiversity models that could contribute to the implementation of the European Digital Twin of the Ocean (EU DTO). The EU DTO will be an operational infrastructure for digital ocean...

Abundance indices are essential data for the application of stock assessment models to obtain fish abundance estimates. Abundance indices have usually been derived from fishery-dependent data, yet the increase in fisheries-independent surveys is now offering new opportunities for these calculations. In this study, we explored the usefulness of icht...

The main objective of the workshop was to review the recommendations of WKREF1 and consider how these might feed into a new reference points framework and guidelines for ICES. There were a number of presentations on the wider issues of best practice for reference points, the Allee effect, density dependence and the WKIRISH approach. The starting po...

The ICES Workshop on ICES reference points (WKREF1) was tasked to provide a thorough review of the ICES reference points system as a basis to re-evaluate the process for estimating, updating and communicating reference points in the context of the ICES advice. As part of the preparation leading to WKREF1 a large database of the most recent assessm...

The ICES Working Group on Mixed Fisheries Advice (WGMIXFISH-ADVICE) met remotely to produce mixed fisheries forecasts for the Bay of Biscay, Celtic Sea, Iberian Waters and North Sea. Mixed fisheries advice highlights the potential implications of single-stock (total allowable catch and effort) management on the catches of multiple stocks caught tog...

The ICES Working Group on Mixed Fisheries Methodology (WGMIXFISH-METHODS) met to progress work on the improvement and development of the mixed fisheries advice. In this report the group provides a summary of the work completed in 2021. Work continued on the full review and documentation of the mixed fisheries advice production process, including wo...

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 f...

The ICES Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE) assesses the status of 23 stocks that are present in ICES divisions 3.a through Subarea 9, but primarily assess stocks distributed across subareas 7, 8, and 9. The group was tasked with conducting assessments of stock status for 18 stocks using analytical models,...

The shifting policy focus towards Ecosystem Based Management in Fisheries (EBFM) requires the integration of knowledge and disciplines and the engagement of stakeholders to support decision-making processes. Scientists contribute to this through (i) participatory research projects, (ii) stakeholder partnerships and (iii) institutional scientific ad...

This workshop is the third in a series of workshops on guidelines for developing Management Strategy Evaluations (MSEs) within ICES, and was intended to explore some of the issues that arose out of workshops that actually developed MSEs for a range of ICES stocks since the second MSE guidelines workshop was held in early 2019. It is intended that r...

The ICES Working Group on Mixed Fisheries Advice (WGMIXFISH-ADVICE) chaired by Claire Moore, Ireland, met at ICES headquarters in Copenhagen, Denmark, 28 October–1 November 2019 to produce mixed fisheries forecasts for the North Sea, Celtic Sea, and Iberian waters. Mixed fisheries advice highlights the potential implications of single-stock (total...

The ICES Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE) assesses the status of 23 stocks distributed from ICES Divisions 3.a–4.a though to Subarea 9, mostly distributed in Subareas 7, 8 and 9. The group was tasked with conducting assessments of stock status for 14 stocks using analytical, forecast methods or trends ind...

Multiannual management plans are increasingly used to manage fishery systems in Europe. Initially, they were focused on single species, however in the last decade mixed-fishery management plans have emerged to ensure sustainable exploitation of stocks and ecosystems. Quantitative evaluations of the management plans are generally focused on data-ric...

Advice for commercially exploited fish stocks is usually given on a stock-by-stock basis. In light of the ecosystem-based fisheries management, the need to move towards a holistic approach has been largely acknowledged. In addition, the discard bans in some countries requires consistent catch advice among stocks to mitigate choke species limiting fis...

Despite its economic importance, the population structure of the European hake, Merluccius merluccius, is unresolved, and the species is assessed based on two stocks (northern and southern) separated by the Capbreton Canyon. In order to shed light into the European hake population structure, we used Restriction-site-Associated DNA sequencing (RAD-s...

Conducting global sensitivity analysis using variance decomposition methods in complex simulation models with many input factors is usually unaffordable. An alternative is to first apply a screening method to reduce the number of input factors and then apply a variance decomposition method to the reduced model. However, usually selection of input f...

The ICES Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE) assesses the status of 23 stocks distributed from ICES Divisions 3.a–4.a though to Subarea 9, mostly distributed in Subareas 7, 8 and 9. The group was tasked with conducting assessments of stock status for 23 stocks using analytical, forecast methods or trends ind...

The purpose of the meeting was to bring up to date the methodologies and technical specifications that should be incorporated in Management Strategy Evaluation (MSE) work in ICES. The workshop was tasked with reviewing recent methodological and practical MSE work conducted in ICES and around the world, as well as the guidelines provided by the 2013...

The ICES Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE) met at ICES headquarters in Copenhagen, Denmark during 3–10 May 2018. There were 18 participants assessing the status of 23 stocks distributed from ICES Divisions 3.a–4.a though mostly distributed in Sub Areas 7, 8 and 9. The group was tasked with conducting ass...

Marine ecosystems evolve under many interconnected and area-specific pressures. To fulfil society's intensifying and diversifying needs while ensuring ecologically sustainable development, more effective marine spatial planning and broader-scope management of marine resources is necessary. Integrated ecological–economic fisheries models (IEEFMs) of...

Fishery systems are complex systems that need to be managed in order to ensure a sustainable and efficient exploitation of marine resources. Traditionally, fisheries management has relied on biological models. However, in recent years the focus on mathematical models which incorporate economic and social aspects has increased. Here, we present FLBE...

The European Union Common Fisheries Policy has established a discard ban, which states that fish below a reference size cannot be sold directly for human consumption. In a fishing effort-regulated fishery, the discard ban can result in extra handling, storing and landing costs. In an output-regulated fishery, this policy might also limit the effort...

Maximising the long term average catch of single stock fisheries as prescribed by the globally-legislated MSY objective is unlikely to ensure ecosystem, economic, social and governance sustainability unless an effort is made to explicitly include these considerations. We investigated how objectives to be maximised can be combined with sustainabilit...

The ICES Working Group for the Bay of Biscay and the Iberic waters Ecoregion (WGBIE) met in Copenhagen, Denmark during 13–14 May 2016. There were 22 stocks in its remit distributed from ICES Divisions 3.a–4.a though mostly distributed in Sub Areas 7, 8 and 9. There were 21 participants, some of whom joined the meeting re-motely. The group was taske...

The ICES Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE) met in Cádiz, Spain during 4–11 May 2017. There are now 23 stocks in its remit distributed from ICES Divisions 3.a–4.a though mostly distributed in Sub Areas 7, 8 and 9. There were 22 participants, some of whom joined the meeting remotely. The group was tasked...

The landing obligation policy was one of the major innovations introduced in the last Common Fisheries Policy reform in Europe. It is foreseen that the policy will affect the use of fishing opportunities and hence the economic performance of the fleets. The problem with fishing opportunities could be solved if single-stock total allowable catches (...

The purpose of this article is to assess the effectiveness of the collaboration between stakeholders and scientists in the construction of a bio-economic model to simulate management strategies for the fisheries in Iberian Atlantic waters. For 3 years, different stakeholders were involved in a model development study, participating in meetings, sur...

Targets and limits for long-term management are used in fisheries advice to operationalize the way management reflects societal priorities on ecological, economic, social and institutional aspects. This study reflects on the available published literature as well as new research presented at the international ICES/Myfish symposium on targets and li...

Landing obligation (LO) has become a core element on the Common Fisheries Policy (CFP). In this work a bioeconomic simulation tool is used to anticipate the effects of LO in a particular fleet that by its nature is likely to be highly affected by its implementation. These effects are measured in terms of biologic, economic and fleet indicators.Resu...

We tested whether our perception of the performance of the adopted Harvest Control Rule (HCR) for Greenland halibut was robust to using different measures of Reproductive Potential (RP) combined with different assumptions about the stock recruit relationship to drive the stock dynamics in simulations. We tested the HCR using alternative stock recru...

The European hake (Merluccius merluccius) is widely distributed over the shelf of the Northeast Atlantic Ocean. This shelf is characterised by the dominance of mesoscale structures that strongly influence the survival of M. merluccius. Spatial as well as depth preferences vary during the life history of M. merluccius, showing an ontogenetic distrib...

The main objectives of this study are:  Description of four case studies considered as the most representative multispecies and mixed fisheries in EU waters.  Analysis of recent improvements on selectivity and identification of species with high survival rate.  Discuss the application of the MSY approach in multispecies fisheries and ecosys...

Deepwater fish are characterized by long lifespans, late maturity and low productivity. This implies slow recovery from low biomass levels and it is, therefore, important to manage these stocks correctly to avoid overfishing. However, these stocks are generally data poor, which it makes difficult to apply quantitative assessment models on which to...

14 Fisheries management is moving towards ecosystem based management instead of traditional single 15 species based advice. To progress towards an ecosystem approach, a new methodology called 16 "Fleet and Fisheries Forecast" (Fcube) has been proposed. In the application of the method, a 17 precise initial fleet and metier segmentation used is impo...

In this paper a classification into metiers of the trawling fleet of the Basque Country (North East of Spain) operating in the Northeast Atlantic ICES Subareas VI, VII, and Divisions VIIIa,b,d from 2003 to 2008 is presented. Principal Component Analysis (PCA) and Cluster analysis approach are used to obtain homogeneous groups of metiers using trip...

The purpose of the present study was to investigate the robustness of the management procedure (MP) of Northern European hake to alternative indices of reproductive potential (RP) based on our recently improved understanding of hake reproductive biology using a Management Strategy Evaluation (MSE) framework. MSE simulations allow the testing of the...

The influence of innovative management alternatives (participatory governance, effort management, decision rules) on biological robustness (BR) in various fisheries relevant to the EU (Baltic, Western Shelf, Faroe Islands, North Sea), was investigated with a numerical simulation model developed in the EU projects EFIMAS (2004–2008) and COMMIT (2004...

SUMMARY We show by means of simulation that the weighted least square indexes of abundance obtained from a linear model can result in an overestimation of the abundance in certain situations and that this does not happen with the un-weighted ones. RÉSUMÉ

The purse seine fishery in the Western Indian Ocean is dominated by Spanish and French vessels that rely heavily on the use of drifting fish aggregation devices (DFADs) to capture tropical tuna species (skipjack, yellowfin and bigeye tuna). This study uses local ecological knowledge (LEK) obtained through standardized interviews of fishing masters...

Kell, L. T., Mosqueira, I., Grosjean, P., Fromentin, J-M., Garcia, D., Hillary, R., Jardim, E., Mardle, S., Pastoors, M. A., Poos, J. J., Scott, F., and Scott, R. D. 2007. FLR: an open-source framework for the evaluation and development of management strategies. – ICES Journal of Marine Science, 64: 640–646. The FLR framework (Fisheries Library for...

In the last stock assessment, CPUE for the Bay of Biscay bluefin tuna was standardized and used as tuning index of ages 2 and 3. CPUE by commercial category was converted to age, a delta-lognormal model was used for the standardization and least square means for the year:age interaction were used to tune the VPA. In this document we revise this sta...

Standardized CPUE series using a Generalized Linear Model for Greenland halibut in Div. 3LMNO, based on catch and effort data from the Spanish trawl fleet since 1991 are presented. Fixed factors considered in the model were: year, month, vessel, Division and depth and the interactions analysed were: Division - depth and month - Division. All the fa...

SUMMARY Following SCRS recommendations, an attempt to fit MULTIFAN-CL to albacore stocks is made with the purpose of illustrating the potential use of this software in future stock assessments. In general, the use of MULTIFAN-CL looks very promising both for the southern and the northern stock, and it is suggested that an informal group carry out t...