Cyclostomes and fishes of the drainage basin of the river Płociczna

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.