Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures
We analysed length structure of European eel (Anguilla anguilla) stocks with a simple size-structured model including a linear trend of recruitment, a linear growth curve, a negative exponential mortality and a silvering process based on a gamma function. Eels shorter than 30 cm were excluded from t...
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ftccsdartic:oai:HAL:hal-02588621v1 2023-05-15T13:27:56+02:00 Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures Evaluation du stock local d'anguille dans la Garonne et la Dordogne par analyse des structures en tailles Lambert, Patrick Beaulaton, Laurent Daverat, Françoise Rigaud, R. Ecosystèmes estuariens et poissons migrateurs amphihalins (UR EPBX) Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF) 2006 https://hal.inrae.fr/hal-02588621 en eng HAL CCSD hal-02588621 https://hal.inrae.fr/hal-02588621 IRSTEA: PUB00020846 Ices Annual science conference Maastricht, NLD, 19-23 septembre 2006 https://hal.inrae.fr/hal-02588621 Ices Annual science conference Maastricht, NLD, 19-23 septembre 2006, 2006, pp.19 [SDE]Environmental Sciences info:eu-repo/semantics/conferenceObject Conference papers 2006 ftccsdartic 2020-12-24T05:59:49Z We analysed length structure of European eel (Anguilla anguilla) stocks with a simple size-structured model including a linear trend of recruitment, a linear growth curve, a negative exponential mortality and a silvering process based on a gamma function. Eels shorter than 30 cm were excluded from the analysis in order to limit effect of sex determinism, colonization process and gear selectivity. The data sets used in this study were obtained from Water Framework Directive (WFD) survey and sampling that can be assimilated to Data Collection Regulation (DCR) survey in the Garonne and Dordogne basin covering seven WFD water bodies (from downstream estuary to upstream tributaries). Even if the calibration remained very sensitive to parameter boundaries, this approach allowed calculation of percentages of silver eels per settled yellow eels in each water bodies. The resulting percentages obtained for each water body matched our knowledge of the corresponding anthropogenic pressure levels. The information about eel stock status provided by the present analysis urges to implement management actions in freshwater estuary compartment. This analysis also showed that the trend in mean length of silver eels between compartments can be inversed only by changing mortality and growth. This result explained why longest eels are presently produced upstream where mortality rate is the lowest even though in putative pristine conditions, they would be produced in the estuary. Conference Object Anguilla anguilla Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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ftccsdartic |
language |
English |
topic |
[SDE]Environmental Sciences |
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[SDE]Environmental Sciences Lambert, Patrick Beaulaton, Laurent Daverat, Françoise Rigaud, R. Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures |
topic_facet |
[SDE]Environmental Sciences |
description |
We analysed length structure of European eel (Anguilla anguilla) stocks with a simple size-structured model including a linear trend of recruitment, a linear growth curve, a negative exponential mortality and a silvering process based on a gamma function. Eels shorter than 30 cm were excluded from the analysis in order to limit effect of sex determinism, colonization process and gear selectivity. The data sets used in this study were obtained from Water Framework Directive (WFD) survey and sampling that can be assimilated to Data Collection Regulation (DCR) survey in the Garonne and Dordogne basin covering seven WFD water bodies (from downstream estuary to upstream tributaries). Even if the calibration remained very sensitive to parameter boundaries, this approach allowed calculation of percentages of silver eels per settled yellow eels in each water bodies. The resulting percentages obtained for each water body matched our knowledge of the corresponding anthropogenic pressure levels. The information about eel stock status provided by the present analysis urges to implement management actions in freshwater estuary compartment. This analysis also showed that the trend in mean length of silver eels between compartments can be inversed only by changing mortality and growth. This result explained why longest eels are presently produced upstream where mortality rate is the lowest even though in putative pristine conditions, they would be produced in the estuary. |
author2 |
Ecosystèmes estuariens et poissons migrateurs amphihalins (UR EPBX) Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF) |
format |
Conference Object |
author |
Lambert, Patrick Beaulaton, Laurent Daverat, Françoise Rigaud, R. |
author_facet |
Lambert, Patrick Beaulaton, Laurent Daverat, Françoise Rigaud, R. |
author_sort |
Lambert, Patrick |
title |
Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures |
title_short |
Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures |
title_full |
Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures |
title_fullStr |
Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures |
title_full_unstemmed |
Assessment of eel stock status in Garonne and Dordogne water bodies by analysing length structures |
title_sort |
assessment of eel stock status in garonne and dordogne water bodies by analysing length structures |
publisher |
HAL CCSD |
publishDate |
2006 |
url |
https://hal.inrae.fr/hal-02588621 |
genre |
Anguilla anguilla |
genre_facet |
Anguilla anguilla |
op_source |
Ices Annual science conference Maastricht, NLD, 19-23 septembre 2006 https://hal.inrae.fr/hal-02588621 Ices Annual science conference Maastricht, NLD, 19-23 septembre 2006, 2006, pp.19 |
op_relation |
hal-02588621 https://hal.inrae.fr/hal-02588621 IRSTEA: PUB00020846 |
_version_ |
1766401223342161920 |