Stocking concerns about 20 diadromous species. Before undertaking a stocking action it is necessary to clearly identify the situation, to know if the population is extirpated or not. Stocking is used for 4 reasons: - to sustain an exploited stock ; the efficiency is judged if this act is enable to maintain or increase the production - to sustain a depleted stock; this act is a success if it avoids the extinction of the population or if it helps the population to become self sustaining - to reintroduce a species - to introduce a species. For the 2 last cases, these practices are efficient if they are enable to get self sustaining populations. According to these criteria, the efficiency of the stocking plans realized are highly contrasted. In fact there are lot of difficulties to assess efficiency: - it is a long term process - not enough using of marking tools (to assess survival, distinction between wild and propagated fish) -because managers prefer to increase the number of fish instead increasing tools to control efficiency. To control efficiency it is necessary to set up different actions: - marking all fish stocked - set up controls at different stages to assess growth, behaviour, survival, contribution to reproduction. It is possible to define a guideline to stop stocking: - define stop criteria according to your target - monitor the population (abundance, survival, sex ratio, reproduction migration ~) - stop stocking - verify if the population is self sustaining.