1. Department of Fisheries Bioeconomics, Inland Fisheries Institute ul. Oczapowskiego 10, 10-719 Olsztyn , Poland ; Present address: Polish Angling Association , ul. Bałtycka 2, 11-041 Olsztyn , Poland
2. Department of Ichthyology, Hydrobiology and Aquatic Ecology, Inland Fisheries Institute , Olsztyn , Poland