There are other varied factors that can disrupt or weaken the maintenance of populations in the wild or curb the restoration of the species.  Although the actual impact on the European sturgeon has not been assessed or the influence of these factors demonstrated, they should nevertheless be mentioned.

- Cohabitation with other sturgeon species
The accidental or intentional presence of allochtonous species of sturgeon that are “exotic” in the open waters frequented by the European sturgeon may have led to the "confusion" experienced by fishermen and may, at the end of the day, prove to be very damaging for the native species.  To these constraints should be added the possibility of hybridisation and the risks of trophic competition that may reduce the reproductive potential and survival capacities at different stags in the life cycle (mainly juveniles).

- Illegal fishing or poaching
In 2000, an enquiry showed the existence in the Gironde estuary plume zone of illegal fishing of European sturgeon.  This poaching activity mainly targeted young individuals from the 1994 reproduction phase, which had by then left this rearing ground for several years.  It seemed highly unlikely that such illegal activities be maintained.  Nevertheless, given the recent release of alevins carried out in this same basin and the knowledge that we have of their life cycle, it is essential to remain watchful in order that poaching does not begin again. To assist in this matter, statutory controls should be increased, both on land and at sea.

- The Allee Effect
This phenomenon of depensation can arise when the density of reproductive adults in the spawning grounds is so low that it is not possible to find a mate in order to reproduce in optimum conditions.  Even in the absence of any other risk of mortality, the population is unable to maintain itself.