Hydroacoustic assessment of pelagic stages of freshwater insects Jan Kubecka, Jaroslava Frouzová, Martin Cech, Jirí Peterka, Henk A. M. Ketelaars, Arco J. Wagenwoort and Miroslav Papácek Aquat. Living Resour., 13 5 (2000) 361-366 Published online: 15 September 2000 DOI: 10.1016/S0990-7440(00)01086-X