Stage 11: Eymet > Pau
Treasures of the Garonne
Stage 11 crosses the meanders of the Garonne in Marmande. The river is classified as a Natura 2000 site from its Spanish sources to the Gironde estuary. It stretches over four departments: Haute-Garonne, Tarn-et-Garonne, Lot-et-Garonne and Gironde.
Around Marmande, the Garonne belongs to the Garonne Natura 2000 site in Aquitaine (FR7200700), which extends over 250 km in Lot-et-Garonne and Gironde. This site contains six habitats of Community interest (alluvial forests, aquatic plant beds, annual vegetation on muddy banks) and 13 animal species of Community interest, including the European sturgeon and allis shad.
Two symbolic species of the Garonne: the sturgeon and the allis shad
These two species are amphihaline anadromous migratory fish, which means that they live in the sea but come to breed in fresh water in the Garonne.
The European sturgeon, well-known and long exploited for its eggs (caviar), is considered a relic of the dinosaur era and can reach more than three meters in length! There are only a few dozen of these fish left in the world, and they live exclusively in the Garonne-Dordogne basin.
As a species threatened with extinction, it is fully deserving of conservation interest at the European level.
The European sturgeon is now being reintroduced into the natural environment from captive breeding.
The allis shad, also threatened with extinction, was abundant until the mid-2000s. Its numbers have decreased abruptly, and we still do not know why, though the cause is likely multi-factorial, such as the presence of obstacles to ecological continuity, poor water quality, unknown factors at sea and the presence of catfish. As a result of the alarming figures, it has been prohibited to catch this iconic Garonne species since 2008.
Despite this measure and work to improve water quality, the population is struggling to recover.
This fish has an astonishing specific feature: its nocturnal egg-laying is very noisy. Individuals perform a noisy mating ritual, with very distinctive sounds caused by the circular movements they perform on the surface of the water, a phenomena called "bulls".
In the middle of the 20th century the residents of the banks of the Garonne complained of the noise during breeding periods!
Follow-up of conservation measures
In order to protect and enhance this ecological richness, from 2011 to 2013, the Syndicat Mixte d'Etudes et de l'Oeuvre de la Garonne (SMEAG), in cooperation with local actors, drew up the Natura 2000 site’s objective document (DOCOB). A true roadmap, this document presents the site’s conservation issues and the actions to be completed to meet them.
The SMEAG has also run the site since April 2014. It thus ensures that concrete actions in favour of biodiversity are implemented, including the implementation of agricultural measures (MAEc) and the signing of charters advocating good practices for those who manage the Garonne’s riverbanks.