Project Description

Project Context :

High altitude lakes, in french Pyrenees and Alps, have been the subject of numerous fish introduction, initially for subsistence, then for recreational fishing. However, some of these lakes were naturally devoid of fish. Fish profoundly alter the lake ecosystem, both through the species present and their impact on the ecosystem's functioning. Fish removal operations are developing worldwide and in France. This actions, still relatively few in number and poorly documented, require rigorous monitoring to assess their effects on the ecosystem and biodiversity.

Project Objectives :

The Mercantour National Park is leading a restoration project for lake Scluos, which involves removing fish. The Pôle ECLA and its scientific partners are commited to monitoring the various components of the ecosystem, both biotic (fish, vegetation, macro-invertebrates, amphibians, zooplankton, etc.) and abiotic (temperature, oxygen and other physicochemical parameters), in order to validate the success of this restoration and quantify its effects on the ecosystem.

Project Results

Pre-restoration monitoring was implemented in 2024 and 2025 for all components. Fish removal began in the summer of 2025 and will continue for several years. The monitoring is maintained throughout the restoration work and will be expanded once eradication is complete, in order to detect any changes affecting biological communities and abotic parameters. This long-term project aims to deepen our understanding of the ecosystem’s evolutionary trajectory and the restoration potential of lake ecosystems through fish removal.

To go further

Contact : marlene.rolan-meynard[at]ofb.gouv.fr