Habitat use by diadromous fish

Habitat use, step 1: Using telemetric methods to study the movement of migratory fish in the Sélune river before dam removal


Emilien Lasne (UMR ESE)

Scientific context

One of the major challenges in restoring ecological continuity in the Sélune basin is the recolonization, by migratory fish species, of the areas located upstream of the dams which offer significant habitat potential. The hypothesis of a relatively rapid and massive recolonization of these areas was a strong argument to motivate the removal of the dams, knowing the conservation issues related to these fish populations. This project focuses on the Atlantic salmon (anadromous species) and the European eel (catadromous species) in its yellow stage.


This project has a double ambition:

  1. The use of telemetry as a monitoring method. Telemetry protocols are generally well mastered, whether it is the installation of a detection network or fish tagging. The main obstacle concerns the protocol for catching salmon in the Sélune estuary which will be developed as part of this project. Concerning the yellow eel, the capture protocols are mastered.
  2. The production of the first elements allowing the characterization of the use of downstream pre-removal habitats by diadromous fish.


In order to characterize the movements and to identify the habitats used by salmon and eel in the Sélune basin after the removal of the Vezins and La Roche-qui-Boit dams, this project proposes the establishment of a radio telemetry protocol.

  1. Radio detection antennas are installed in the Sélune basin at the entrance of the main tributaries and along the main course of the river. Additional antennas are also installed downstream from the other tributaries of the Bay of Mont Saint Michel in order to identify possible movements between tributaries.
  2. Salmon spawners are captured in the Sélune estuary during their anadromous migration (in spring and summer) and are equipped with radio transmitters.
  3. Yellow eels are caught downstream of the La Roche-Qui-Boit dam and are also equipped with transmitters.

Laboratories involved

Muséum national d’histoire naturelle, Station marine de Dinard

Unité BOREA – Biologie des Organismes et Ecosystèmes Aquatiques