Chapter 4 dataset – Read me file 1. Site level data Observation_ID Unique ID given to each site surveyed by electrofishing Treatment Treatment assignation as either ‘Trout-free’ or ‘Trout-populated’ stream reaches Stream_Reach Unique ID given to each experimental stream reach Displacement_to_release_site Distance (m) between the centre of the electrofishing site and the centre of the release site of the given stream reach (upstream distances are shown as negative values) Eel_N Number of eels recorded, inclusive of captured and missed fish, during the electrofishing survey at the site Eel_density_fish_m-2 Density (fish m-2) of eels recorded, inclusive of captured and missed fish, during the electrofishing survey at the site Eel_mean_total_length_mm Mean total length (mm) of all eels captured during the electrofishing survey at the site Trout_mean_fork_length_mm Mean fork length (mm) of all trout captured during the electrofishing survey at the site 0+_Trout_N Number of 0+ age class trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site 1+_Trout_N Number of 1+ age class trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site 2+_Trout_N Number of 2+ age class trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site Adult_Trout_N Number of adult trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site 0+_Trout_density_fish_m-2 Density (fish m-2) of 0+ age class trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site 1+_Trout_density_fish_m-2 Density (fish m-2) of 1+ age class trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site 2+_Trout_density_fish_m-2 Density (fish m-2) of 2+ age class trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site Adult_Trout_density_fish_m-2 Density (fish m-2) of adult trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site Total_Trout_density_fish_m-2 Density (fish m-2) of all trout recorded, inclusive of captured and missed fish, during the electrofishing survey at the site Site_Area_m2 Area (m2) of electrofishing site Altitude_m Altitude (m) of electrofishing site Flow_level Flow level during electrofishing surveys, classed as ‘Low’ in all cases Pool_% Percentage of site area made up of pool habitat, visually estimated Riffle_% Percentage of site area made up of riffle habitat, visually estimated Smooth_% Percentage of site area made up of smooth/glide habitat, visually estimated Mean_depth_cm Site mean depth (cm) Silt_% Percentage of site area covered by silt substrate, visually estimated Sand_% Percentage of site area covered by sand substrate, visually estimated Gravel_% Percentage of site area covered by gravel substrate, visually estimated Cobble_% Percentage of site area covered by cobble substrate, visually estimated Boulder_% Percentage of site area covered by boulder substrate, visually estimated Bedrock_% Percentage of site area covered by bedrock, visually estimated Cover_index Cover index calculated based upon the proportion of wetted channel with large/small woody debris, undercut banks, aquatic vegetation, boulder cover and overhanging vegetation. 2. Stream level data Stream_Reach_ID Unique ID given to each experimental stream reach Stream_Name Local name given to each stream River Name of broader catchment into which each stream eventually flows Treatment Treatment assignation as either ‘Trout-free’ or ‘Trout-populated’ stream reaches Stream_pH Stream pH measured at a single point within each stream reach Temp_C Stream temperature (°C) measured at a single point within each stream reach Conductivity Stream conductivity (?mhos cm-1) measured at a single point within each stream reach Stream_length_km Total stream length above impassable barrier (km) Stream_gradient_% Overall stream gradient across the entire stream reach Highest_stream_altitude_m Highest altitude of the surveyed stream Watershed_Area_km2 Watershed area (km2) of stream above impassable barrier Mg Concentration of Magnesium (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Ca Concentration of Calcium (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Na Concentration of Sodium (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) K Concentration of Potassium (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Cl Concentration of Chloride ions (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) NO3 Concentration of Nitrates (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) SO4 Concentration of Sulphates (mg l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Al Concentration of Aluminium (ng l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Fe Concentration of Iron (ng l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Zn Concentration of Zinc (ng l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Pb Concentration of Lead (ng l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Mn Concentration of Manganese (ng l-1) measured at a single point within each stream reach using inductively coupled plasma mass spectrometry (ICPMS) Eel length data Stream_Reach Unique ID given to each experimental stream reach Treatment Treatment assignation as either ‘Trout-free’ or ‘Trout-populated’ stream reaches Displacement_to_release_site Distance (m) between the centre of the electrofishing site and the centre of the release site of the given stream reach (upstream distances are shown as negative values) Eel_total_length_mm Total length (mm) of individual eel measured Site_mean_eel_total_length_mm Mean total length (mm) of all individual eels measured at that site Stream_Reach_mean_eel_total_length_mm Mean total length (mm) of all individual eels measured within that stream reach Trout length data Stream_Reach Unique ID given to each experimental stream reach Displacement_to_release_site Distance (m) between the centre of the electrofishing site and the centre of the release site of the given stream reach (upstream distances are shown as negative values) Trout_fork_length_mm Fork length (mm) of individual trout measured Site_mean_trout_fork_length_mm Mean fork length (mm) of all individual trout measured at that site Stream_reach_mean_trout_fork_length_mm Mean fork length (mm) of all individual trout measured within that stream reach