Part of the lower Drawa River between Dubie Lake and the Plociczna River mouth, stretching for a distance of 38.8 km, belongs to the Drawieilski National Park, established in 1990. Electrofishing conducted on the 8 river stretches within the park limits yielded a total of 26 fish species and one cyclostomate species. The leading species appeared to be the roach, with the domination level reaching 56.16%. The other abundant species were: burbot (D = 7.81%), silver bream (D = 6.88%), and perch (D = 5.95%). The remaining species occurred in smaller numbers. The Drawa River within the Park limits is inhabited by 3 species of the family Cyprinidae: min now-Phoxinus phoxinus, schneider-Albumoides bipuncta tus, and bitterling-Rhodeus sericeus amarus, all under strict protection and one cyclostomate species of the family Petro myzonidae-river lamprey-Lampetra jluviatilis, protected at the stage of larval development.
The present paper shows the age, mean length, and weight of smolts of the migratory morphotype of the brown trout, grown in the drainage area of the Gowienica River (Pomera nia). The above parameters are given separately for both sexes and all age groups. Because the scales of the smolts were in the period of annual ring formation, the age determination was preceded by counting the annual rings and analyzing the edge increments. The study was based on a total of 277 smolts ac quired in four fishing seasons covering the years of
Studies on the occurrence of cyclostomes and fishes of the drainage area of the river Plociczna were carried out in 1996. The following parameters were defined: constancy of occur rence (C), domination index (D), and fractions of the biomass (W) represented by individual species. The results were con fronted with the data from the river Plociczna published by the other authors within 1986-1994. A total of 1 cyclostome and 32 fish species was presently recorded to inhabit the drainage area of the river Plociczna. In this number there were 1 cyclostome and 7 fishes which are protected species. The part of the dra inage area of the Plociczna under study, constitutes a section of the Drawienski National Park. The species occurring in that part, as well as in its buffer zone were discussed.
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