Action Plan for a critically endangered Freshwater Pearl Mussel in Czechia – achievements of semi-natural breeding and population reinforcement in contrast with protracted restoration of its oligotrophic river ecosystems

Simon O. P., Hruška J., Horáčková J., Dort B., Douda K., Švanyga J., Bílý M., Švaříčková J.

simon@fzp.czu.cz

Even at the beginning of the 20th century, a strong population of freshwater pear mussel (FPM) amounting millions of individuals lived in many Czech rivers. During the 20th century, this bivalve gradually lost up to 95% of its original distribution area as well as many other organisms associated with this type of habitat due to a number of anthropogenic interventions in river ecosystems. At present, its last population is limited to the border area of Bohemia, where the last hundreds to thousands of individuals live in the catchment area of five rivers. At the most of them the species stopped its spontaneous reproduction. Since 1980, due to an alarming decline of FPM population, missing reproduction and the deteriorating quality of entire unique oligotrophic river catchments, the activities to protect them are ongoing. Gradually, declarations of a first action plan for the FPM and its habitats and declaration of protected areas in most of FPM catchments with a detailed plan for the care of the entire ecosystem were being processed. Since 1990, successful semi-natural breeding of FPM and an invading of its host-fish brown trout progressed in order to population reinforcement in individual rivers (for details, see talk Simon et al.). Many rivers have undergone a number of more or less successful river restorations and measures to protect the entire ecosystem and pearl mussels as a flagship species over the last 40 years. Nevertheless, despite of many successes of the action plan, all measures to save and support local ecosystems and their unique habitats are realized too slowly.