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Suivi des alosons dans les parties aval de la Garonne et de la Dordogne : Année 2017 et synthèse 2013-2017

Abstract : The Allis Shad population experiences a strong decline in the Garonne - Dordogne basin. A problem of recruitment was identified. The first studies showed, in certain conditions, the negative effect of abiotic factors (temperature, oxygen), but they cannot account alone for the weakness of the cohorts sampled in estuary. The general objective of this study is to improve our knowledge on the downstream migration phase. In this context it seems necessary to determine the respective part of each of the rivers in the natural juvenile production. From 2013, experimental samplings were realized from June till October in the downstream part of the Garonne and the Dordogne Rivers, with the cooperation of a professional fisherman. The 2017 season was marked by a very low number of catches (186) and the absence of allis shad. The synthesis of the data on the study as a whole highlights 3 points in particular. Maintaining oxygen levels is a point of vigilance, because during some campaigns the levels are on the limit of tolerance for juveniles of allis shad. The capture of large individuals at the beginning of the season suggests that some of the recruits remain in fresh water during the first year. The distinction between the 2 species is possible up to a limit size of 33 mm in standard length.
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https://hal.inrae.fr/hal-02607944
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Submitted on : Saturday, May 16, 2020 - 2:54:45 PM
Last modification on : Wednesday, November 3, 2021 - 6:24:32 AM

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  • HAL Id : hal-02607944, version 1
  • IRSTEA : PUB00058882

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Philippe Jatteau, Stéphane Bons, Romaric Le Barh, Patrick Lambert. Suivi des alosons dans les parties aval de la Garonne et de la Dordogne : Année 2017 et synthèse 2013-2017. [Rapport de recherche] irstea. 2018, pp.38. ⟨hal-02607944⟩

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