The Chornaya gudgeon (Gobio delyamurei), a critically endangered species known to live in a single river in Ukraine, is in danger of being wiped out because its waters are being diverted for farmland irrigation, the study revealed.
Listed among the already extinct species is the houting, a herringlike coastal fish that migrated up rivers in northern Europe to spawn.
Most of the extinct fish recorded in the study lived in Central Europe during the 1970s and '80s.
These species most likely were victims of pollution, said the handbook's co-author Jörg Freyhof of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, Germany.
"Now water [extraction] is the major problem, especially in the Mediterranean and the south of Europe, where about [a third] of the endangered species occur," Freyhof said.
In general, the declines are largely due to the last hundred years of human environmental impacts, such as dam construction, water extraction, and the introduction of non-native species, the experts noted.
Water removal in some parts of Europe has caused rivers to dry up in summer months, a problem exacerbated by climate change impacts, the study authors say.
"A hot spot for endangered species is southern Spain and Portugal," Freyhof said.
"Desertification is already a major problem in the region. If you pump out the rivers there, it doesn't help."
The introduction of non-native species is the second most serious threat to European fish diversity, the scientist added.
In Spain and Portugal, for instance, predatory pike introduced from Central Europe and largemouth bass introduced from North America have proved "disastrous," Freyhof said.
"These fish eat all the native fauna, which are not adapted to predation at all," he said.
Likewise, introduced brown trout from northern Europe have seriously jeopardized endemic trout populations in Balkan countries, Freyhof said.
Other regions where freshwater fish face the highest risk of extinction include the lower reaches of the Danube, Dnister, Ural, and Volga rivers in Eastern Europe.
According to IUCN's Darwall, the endangered fish "are an important part of our heritage and are critical to the freshwater ecosystems upon which we depend, such as for water purification and flood control.
"Many of these species can be saved through relatively simple measures," he added. "All we need is the public and political will to make it happen."
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