<p>Despite ongoing high stocking efforts and extensive natural reproduction in the meantime, salmon return numbers on the Rhine have been declining sharply since 2014/2015. Other anadromous species such as sea trout, shad and sea lamprey are also affected by the decline, which points to universally acting stressors. A study commissioned by the International Commission for the Protection of the Rhine (ICPR) identifies the stressors affecting anadromous species. A key objective of the study is to compare the stock situation and stressors at the beginning of the 2000s with the current situation, i.e. to highlight which stressors exist (where possible with localisation and hierarchisation) and have increased in their impact over the corresponding period. Marine mortality, predation, shipping traffic and hydroelectric power plants, among other things, were identified as increasing stressors, with increasingly lower discharges in the Rhine system increasing the impact of various stressors. Given the current insufficient data, weighting the effects of the identified stressors over the entire life cycle of salmon is subject to considerable uncertainty. The contribution of individual stressors to the decline in salmon could not be extracted from the data, especially since none of the data sets used directly reflected the impact processes of the stressors.</p>