The European grayling, Thymallus thymallus (L.), is one of the most important, valuable commercial fish species in Poland. Three basic parameters describing angling pressure on this fish in the Dunajec River catchment were analyzed: mean monthly catch per angler, total catch per anglers belonging to the various branches of the Polish Anglers Association, and total catch per angling district. It was found that a total of 74 014 grayling specimens (weighing 25 511.1 kg) were caught in the Dunajec catchment in the period of 1999-2011. In the beginning, annual catch increased rapidly, with the maximum in 2002, when 20 796 specimens weighing 6810.2 kg were taken by anglers. Since then, the catch has decreased gradually. In 2004, the number of grayling harvested decreased by 66.3 %, and in the following year an additional 52 % decrease was observed. Despite conservation measures undertaken by the Polish Anglers Association, catches continued to decrease in subsequent years. The results presented, along with considerations on the origin of stocking material released in the Dunajec catchment, suggest a serious disruption in the phylogenetic integrity of the populations of the gray ling in this river system might have occurred, resulting in the decline in recreational catches. It is recommended that the the stocking material released into the Dunajec River catchment is of high quality and phylogeographic unity; otherwise, the conservation of the European grayling could be wholly unsuccessful.
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