host one to four endemic species of Coregonus as well as endemic species of Salvelinus. Several of these endemic species became Extinct in the 20th century. Another centre of freshwater fish endemism exists in northern Europe, in Iceland, Ireland, Scotland, Wales, Norway, Sweden, Finland and Russia. Many postglacial lakes of that region are home to unique Coregonus and Salvelinus populations that are still not recognized as distinct conservation units.
hosts a unique fauna. Most of these river systems are currently unprotected, and their fish fauna exposed to high pressures from alien species or habitat destruction. 3.3.4 Data Deficient species
Figure 8 shows the distribution of Data Deficient (DD) freshwater fish species (e.g. those for which there is not enough information to assess them against the IUCN Red List criteria). The highest numbers of DD species are found in the Eastern Adriatic basin, especially in Albania, where the knowledge on the conservation status, distribution and taxonomy of freshwater fishes remains very poor.
In the tributaries of the Mediterranean and the western Black Sea coast and Crimea, the species diversity per water body is low, whereas the rate of endemism is high. Many species occur in just one catchment, in few springs or streams, and about 60% of all freshwater fishes assessed as Critically Endangered in Europe occur in this area. Overall, our knowledge about the diversity of Mediterranean freshwater fishes is still incomplete; many new species have been described in recent years. Well known hotspots of endemism include the poljes (plains) and streams of the Dinaric karst in Croatia and BosniaHerzegovina, the southern Balkan region of Greece, FYR of Macedonia, southern Bulgaria, the tip of Crimea and European Turkey. Almost every river in these regions
3.4 Major threats to freshwater fishes in Europe The major threats to each species were coded using the IUCN Threats Classification Scheme (see http://www. iucnredlist.org/technical-documents/classificationschemes). A summary of the relative importance of the different threatening processes is shown in Figure 9.
Figure 8. Distribution of Data Deficient fishes in Europe
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