Spatial variability in the growth of invasive European barbel Barbus barbus in the River Severn basin, revealed using anglers as citizen scientistsFatima Amat Trigo, Catherine Gutmann Roberts and John Robert BrittonKnowl. Manag. Aquat. Ecosyst., 418 (2017) 17DOI: https://doi.org/10.1051/kmae/2017009