# Evaluating Silver Eel Escapement at a Large Scale Using Eel Density Analysis (EDA)

María Mateo, Estibaliz Díaz, Laurent Beaulaton, Hilaire Drouineau, Carlos Antunes, Elsa Amilhat, Agnes Bardonnet, Maria João Correira, José Lino Costa, Anna Costarrosa, et al.

► To cite this version:

María Mateo, Estibaliz Díaz, Laurent Beaulaton, Hilaire Drouineau, Carlos Antunes, et al. Evaluating Silver Eel Escapement at a Large Scale Using Eel Density Analysis (EDA). Biology and Life Sciences Forum, 2022, 13 (1), 10.3390/blsf2022013095. [DOI: 10.36990/bsf.2022.13.013095](https://doi.org/10.36990/bsf.2022.13.013095)

HAL Id: hal-03699085

https://hal.science/hal-03699085

Submitted on 20 Jun 2022

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
Abstract

# Evaluating Silver Eel Escapement at a Large Scale Using Eel Density Analysis (EDA) †

María Mateo <fnref n="1" />,*,‡ ID, Estibaliz Díaz <fnref n="1" />, Laurent Beaulaton <fnref n="2" /> ID, Hilaire Drouineau <fnref n="3" /> ID, Carlos Antunes <fnref n="4" /> ID,
Elsa Amilhat <fnref n="5" />, Agnes Bardonnet <fnref n="6" />, Maria João Correira <fnref n="7" />, José Lino Costa <fnref n="7" />, Anna Costarrosa <fnref n="8" />,
Ramón J. de Miguel Rubio <fnref n="9" /> ID, Isabel Domingos <fnref n="7" />, Elisabeth Faliex <fnref n="5" /> ID, Carlos Fernandez Delgado <fnref n="9" /> ID,
María Korta <fnref n="1" /> ID, Mathilde Labedan <fnref n="10" />, Rui Monteiro <fnref n="7" /> ID, Ana Moura <fnref n="4" /> ID, Teresa Portela <fnref n="7" />, Pierre Sagnes <fnref n="10" />,
Gaël Simon <fnref n="5" />, Lluis Zamora <fnref n="8" /> ID and Cédric Briand <fnref n="11" /> ID

<figure><img src="image_2.png" /></figure>

check for
updates

**Citation:** Mateo, M.; Díaz, E.; Beaulaton, L.; Drouineau, H.; Antunes, C.; Amilhat, E.; Bardonnet, A.; Correira, M.J.; Costa, J.L.; Costarrosa, A.; et al. Evaluating Silver Eel Escapement at a Large Scale Using Eel Density Analysis (EDA). *Biol. Life Sci. Forum* **2022**, *13*, 95. https://doi.org/10.3390/ blsf2022013095

Academic Editor: Alberto Teodorico Correia

Published: 15 June 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

<figure><img src="image_3.png" /></figure>

**Copyright:** © 2022 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

**Abstract:** The European eel population has declined over the last 50 years and is outside safe biological limits. In 2007, the European Commission enforced a regulation to ensure that all Member States implement Management Plans to achieve an escapement rate of 40% for silver eels. However, escapement is assessed using diverse methods, and therefore, estimates of different countries are not comparable. Thus, European scientists and managers face the challenge of finding a method that could be applied all along the European eel distribution range using widely available data. During the SUDOANG project, the Eel Density Analysis model (EDA) was used to estimate the silver eel escapement in Spain, France, and Portugal. EDA can estimate silver eel escapement at different scales (basin, EMU, country, international) using data from routine electrofishing surveys, such as those collected for the Water Framework Directive (WFD). EDA is based on open-source software and is widely applicable to European rivers. A chained river network in the three countries was built, including the hydrological attributes, the location, and the characteristics of 10,574 obstacles. A total of 46,118 electrofishing operations from 1985 to 2019 were also compiled and projected to the hydrographic network. Finally, EDA was implemented through the sub-models on eel presence-absence, density, size structure, and silvering. EDA estimated a total fluvial population of 12.3, 11.7, and 5.8 million silver eels for 2015 in France, Spain, and Portugal, respectively. Eel presence and abundance decreased as the altitude and the distance to the sea increased. Finally, by setting the

<footnote n="1">1 AZTI, Sustainable Fisheries Management, Basque Research and Technology Alliance (BRTA), 48395 Sukarrieta, Spain; ediaz@azti.es (E.D.); mkorta@azti.es (M.K.)</footnote>

<footnote n="2">2 Service Conservation et Gestion Durable des Espèces Exploitées, Direction de la Recherche et de l'Appui Scientifique, OFB & Management of Diadromous Fish in their Environment, OFB, INRAE, Institute Agro, E2S UPPA, 35000 Rennes, France; laurent.beaulaton@ofb.gouv.fr</footnote>

<footnote n="3">3 INRAE, UR EABX, 33612 Cestas, France; hilaire.drouineau@inrae.fr</footnote>

<footnote n="4">4 CIIMAR—Interdisciplinary Centre of Marine and Environmental Research, Universidade do Porto, 4450-208 Matosinhos, Portugal; cantunes@ciimar.up.pt (C.A.); anacatarinamoura@hotmail.com (A.M.)</footnote>

<footnote n="5">5 UMR 5110 CNRS-UPVD, Laboratoire CEFREM, Université of Perpignan Via Domitia, 66100 Perpignan, France; elsa.amilhat@univ-perp.fr (E.A.); faliex@univ-perp.fr (E.F.); gsimon@univ-perp.fr (G.S.)</footnote>

<footnote n="6">6 UMR 1224, Ecobiop, Aquapôle, Pôle Gest'Aqua, Inrae/UPPA, 64310 St Pée sur Nivelle, France; agnes.bardonnet@inrae.fr</footnote>

<footnote n="7">7 Departamento de Biologia Animal, Centro de Ciências do Mar e do Ambiente (MARE), Faculdade de Ciências, Universidade de Lisboa, 1600-548 Lisboa, Portugal; mjcorreia@fc.ul.pt (M.J.C.); jlcosta@fc.ul.pt (J.L.C.); idomingos@fc.ul.pt (I.D.); rmmonteiro@fc.ul.pt (R.M.); tmportela@fc.ul.pt (T.P.)</footnote>

<footnote n="8">8 Grupo de Investigación en Ecología Acuática Continental (GRECO), Instituto de Ecología Acuática, Facultad de Ciencias, Universidad de Girona, 17003 Girona, Spain; acostarrosa@gmail.com (A.C.); lluis.zamora@udg.edu (L.Z.)</footnote>

<footnote n="9">9 Departamento de Zoología, Universidad de Córdoba, 14071 Córdoba, Spain; a92mirur@uco.es (R.J.d.M.R.); ba1fedec@uco.es (C.F.D.)</footnote>

<footnote n="10">10 OFB Pôle de Recherche et Développement en Ecohydraulique OFB-IMFT, 31400 Toulouse, France; mathilde.labedan@toulouse-inp.fr (M.L.); pierre.sagnes@ofb.gouv.fr (P.S.)</footnote>

<footnote n="11">11 EPTB Vilaine, 56130 La Roche Bernard, France; cedric.briand@eptb-vilaine.fr</footnote>

<footnote>* Correspondence: mmateo@azti.es</footnote>

<footnote>† Presented at the IX Iberian Congress of Ichthyology, Porto, Portugal, 20-23 June 2022.</footnote>

<footnote>‡ Presenting author (oral communication).</footnote>
cumulated height of dams to zero, EDA provided an estimate of the effect of habitat loss due to
dams on the eel population. These results correspond to the first assessment of silver eels carried out
simultaneously and with the same methodologies in three European countries.

**Keywords:** European eel; silver escapement; EDA model; habitat loss

**Author Contributions:** Conceptualization, C.B., M.M., E.D., H.D. and L.B.; methodology, C.B., M.M., H.D. and L.B.; software, C.B., M.M. and L.B.; validation, M.K., E.D., L.B., H.D., C.A., E.A., A.B., I.D., C.F.D., P.S. and L.Z.; formal analysis, C.B. and M.M.; investigation, C.B., M.M., E.D., H.D. and L.B.; resources, C.A., E.A., A.B., I.D., C.F.D., P.S. and L.Z.; data curation, M.M., C.B., C.A., E.A., A.B., M.J.C., J.L.C., A.C., R.J.d.M.R., I.D., E.F., C.F.D., M.L., R.M., A.M., T.P., P.S., G.S. and L.Z.; writing—original draft preparation, M.M., C.B. and E.D.; writing—review and editing, M.M., C.B., E.D., L.B., H.D., C.A., E.A., A.B., M.J.C., J.L.C., A.C., R.J.d.M.R., I.D., E.F., C.F.D., M.L., R.M., A.M., T.P., P.S., G.S. and L.Z.; visualization, M.M., C.B., M.K. and H.D.; supervision, C.B., L.B. and E.D.; project administration, E.D.; funding acquisition, E.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was co-financed by the INTERREG SUDOE Programme through the European Regional Development Fund (ERDF).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available in Zenodo: Mateo, M.; Drouineau, H.; Pella, H.; Beaulaton, L.; Amilhat, E.; Bardonnet, A.; Domingos, I.; Fernández-Delgado, C.; De Miguel Rubio, R.; Herrera, M.; Korta, M.; Zamora, L.; Díaz, E.; Briand, C. (2021). Atlas of European Eel Distribution (*Anguilla anguilla*) in Portugal, Spain and France (1.0.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.6021838. Briand, C.; Mateo, M.; Drouineau, H.; Korta, M.; Díaz, E.; Beaulaton, L. (2022). Electrofishing data for eel (*Anguilla anguilla*) in the SUDOE area (1.0.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.6023561. The database is also available for download on the project website: https://sudoang.eu/en/.

**Conflicts of Interest:** The authors declare no conflict of interest.