Management of fish populations in lobelia lakes in the vicinity of Bytów (northern Poland)

The aim of the studies was to describe the fisheries management of five lobelia lakes and one non-lobelia reference lake. Data from commercial catches was used to estimate the size of the catches, and to determine the species and ecologial structure of the catches, and to describe stocking. During the period from 1968 to 2006, eleven fish species belonging to five families were noted in the catches. The species structure of the commercial catches of the analyzed lobelia lakes corresponded to that of either vendace or eutrophic lakes. Catches made in lobelia lakes were from 2.5 to 5-fold smaller in comparison to the reference lake. The dominant species in commercial catches made in basins with lobelia vegetation were roach, Rutilus rutilus (L.), and pike, Esox lucius L., but bream, Abramis brama (L.), vendace, Coregonus albula (L.), and carp, Cyprinus carpio L., also occurred in some lakes. Pike was caught most frequently, followed by bream, roach, and perch. The largest catches were made in either March or November. During the period from 1968 to 2006, the lakes were stocked with ten fish species, nine of which were noted in the official statistics. Only six species occurred naturally in these lakes. Peled, Coregonus peled (Gmelin), is an alien species, and its occurrence was certainly connected with stocking. Pikeperch, Sander lucioperca (L.), was translocated outside of its area of natural occurrence, while carp and Prussian carp, Carassius gibelio (Bloch), were alien species.