More than one out of every three freshwater fish species in European waters is on the brink of extinction, conservationists announced today.

After seven years of research, scientists with the World Conservation Union (IUCN), based in Switzerland, found that 200 of the 522 (38 percent) species of European freshwater fish are threatened with extinction due to rapid development in Europe over the last 100 years. Twelve species are already extinct.

The survey, detailed in a book, Handbook of European Freshwater Fishes, also found 47 new fish species, but this biodiversity is threatened in many of Europe's lakes and rivers.

"This new study shows that we are far from achieving European governments' targets to halt biodiversity loss by 2010," said Jean-Christophe Vie of the IUCN's Species Program. "The status of fish populations reflects the condition of European lakes and rivers."

Over the past century, many large dams have been built on Europe's rivers for irrigation, flood control and power generation, but have also led to the local extinction of many migratory fish species.

Overfishing and then introduction of alien species (and their diseases) have also contributed to fish deaths.

The primary threat to fishes is likely water abstraction—the process of taking water from one source to use elsewhere, says the IUCN, which produces an annual list of endangered species. This had led to many rivers drying up in the summer months.