Threats :Wild trout populations are threatened by a variety of factors:
- water pollution to which trout are considered very sensitive, particularly when it reduces the oxygen content in the water
- artificialization of watercourses, often associated with the destruction or degradation of spawning grounds and habitats favourable to wild salmonids (wood jams, banks and bottoms rich in caches and microhabitats, riparian areas, etc.)
- certain diseases (parasitosis, bacterial and viral diseases) that can be favoured by water pollution, and inbreeding, sources of immune depression
- artificial obstacles to trout migration (large dams and thresholds or other impassable dams, discharges of warm and/or very oxygen-depleted waters, discharges of repellent or toxic substances for trout) hinder their circulation between growth and reproduction areas, and may prevent or hinder the natural recolonisation of certain rivers
- genetic pollution, depletion of genetic variability, and certain hybridizations (in particular those detectable by electrophoresis), after the escape of fish farm animals or following restocking introductions.