Why is fighting against the Louisiana crayfish necessary?


An alien invasive species is a species willingly or accidentally introduced by man in an area outside of its natural range and whose establishment and spreading threaten the local ecosystems, habitats or species, with negative ecological, economical or even health consequences.

Introduced in France in 1976 for human consumption, the Louisiana crayfish is now recorded in 70 departments, versus 61 in 2006. Highly adaptable, omnivorous and opportunistic, the Louisiana crayfish interacts with amphibians, in different ways: predatorily, aggressively, competitively, etc.

Beyond the damages brought to the local species, the species damages the riverbanks and has an impact upon the functioning of the ecosystems it colonises, leading to a delicate balance typical to the retreat of vegetal communities and macro-invertebrates.

The presence of Louisiana crayfish in the La Capelle pond and puddles site has been acknowledged and monitored in said pond since 2009. The protocol has been updated in 2017 in order to explore all of the plateau’s puddles, on the west side of the Natura 2000 site. A total of 10 puddles have been inhabited at least once by the species since the monitoring started.

Since 2018, it has been stated that the presence of this crustacean has significantly increased within the pond, especially in the fishing area. This phenomenon follows the complete and extensive draining that had caused that year the disappearance of a whole fish population, including carnivorous fish that were actively involved in limiting this alien invasive species population.

It is therefore necessary to ensure that local species coexist with the Louisiana crayfish until its extinction. Thus, the fight against this alien invasive species is built around several means:

  • Keep animal homes for the native species
  • Wipe out the present individuals
  • Avoid any new prohibitions
  • Raise the awareness of the locals and users

What shall we do in order to fight against the Louisiana crayfish?

  • In the puddle network, the work on creating and rehabilitating puddles shall allow these shelters to be preserved for the local species, including the rare great crested newt. Selective restraints shall also be set in order to stop this crustacean from crossing to the other side.
  • Around the pond, participatory capture site for catching crayfish using traps shall be organised according to a strict protocol.
  • The crayfish shall be poisoned in order to favour their predation by carnivorous fish. The fishing practices shall be adapted in cooperation with the fishermen.

The project throughout time

  1. Step 01 - From 2022 to 2026

    Participatory capture sites

  2. Step 02 - Winter 2023

    Carnivore intoxication