Many water systems suffer from reduced or completely disrupted connectivity due to human activities, causing negative effects for species and ecosystems. Artificial transport past migration barriers, so called trap-and-transport, can be used as a management tool to mitigate fish population declines. The efficiency of trap-and-transport is, however, rarely evaluated, in particular for downstream transport of catadromous species such as the European eel. In this study we analysed seven years of trap and transport data (2016-2022), encompassing more than 65 000 transported eels, to evaluate stress and mortality during all steps of the trap and transport process. We found that average mortality rate was generally low but could be as high as 10%. Mortality during all steps of the trap and transport procedure was affected by temperature, with higher temperatures leading to higher mortality. We also found that when mortality in the fishing gear had been high, mortality during holding was also high. Mortality during transport was additionally affected by transport time, with longer transport time causing higher mortality. In addition to mortality rates, we also evaluated stress during trap and transport by surgically implanting biologgers measuring heart rate, which was used as a proxy for stress. Similar to mortality, stress was affected by temperature, with higher temperatures causing higher stress levels, in particular during transport. We conclude that although trap-and-transport, fishways, and other alternatives aiming at reducing negative impacts can reduce mortality, such measures require maintenance and human interference, wherefore removal of migration barriers should be the long-term goal.