Boxplots showing changes in density of European eel in the restoration and control reaches of the River Glaven during the study period following a randomization approach. Top plot: boxplot showing bootstrapped density values during pre-restoration (1), post-embankment removal (2–3) and post-re-meandering (4–7). Bottom left plot: boxplot showing averaged bootstrapped densities per Treatment and Reach, where a = pre-restoration, b = post-embankment removal, and c = post-re-meandering. Bottom right plot: boxplot showing difference in bootstrapped densities between restoration and control reach per Treatment. Dark black horizontal line represents 50% of the data, light black horizonal lines represent 25% and 75% of the data (Interquartile Range − IQR) and light black vertical lines minimun and maximum data values in comparison to IQR. Dark black dots represent outliers.