Catch per unit of effort (CPUE) of Perccottus glenii in lakes Beržuvis (A), Bevardis (B), Cirkliškis (C), and Stūgliai (D) studied before (Pre: 2012–2013), during (Transitional: 2014–2015), and after (Post: 2017) the implementation of biocontrol measures, i.e. the introduction of native piscivorous fish species (median, quartiles, range). Small letters (a, b) denote homogeneous groups according to Mann-Whitney U tests.