Reconstructing the build-up of a pelagic stickleback (Gasterosteus aculeatus) population using hydroacoustics

•Sticklebacks dominate the pelagic fish community of an oligotrophic lake during recent years.•Hydroacoustic surveys document the rapid emergence of this population.•After its establishment population density fluctuated around 3880 fish per hectare.•Maximum density observed was 7990 fish per hectare.