Riverine Fish Fauna In Poland

At present Poland is drained from the Carpathians, located in the southeast, to the Baltic Sea, located in the north-west. In the Pleistocene, however, much of Poland experienced several glaciations, when ice sheets advanced south and retreated. Each one destroyed many river basins and their fish but created periodic connections with the North Sea and Ponto-Caspian catchments. This enabled repeated colonization from fish refugia, which has been discovered using genetic lineage analysis.The scientific knowledge of rivers and fish in Poland has much increased since World War II, owing to the Scientific Annual of the Polish Angling Association, and then European Community/Union initiatives, which classified rivers into 26 abiotic and 15 fish types. Most rivers belong to barbel and bream zones, while environmental factors affect assemblage composition more than historic ones. Fish in 90% of river systems have been investigated, but in only a few monitored more than twice. Out of 53 native fish and lamprey species, the LC category comprises half, other categories 10% each, while EW, EX and DD ones only solitary species.Native fishes are threatened by invasions of non-native ones, 24 of which have appeared in Poland since WWII, by pollution, which was severe in the 1960s-1980s but has now much decreased, and by river regulation and impounding, which continuously stress fish populations. The Polish Angling Association administers most inland waters, 0.5 million ha, which are stocked with fish and exploited by 1.5 million anglers.