UN warns migratory freshwater fish numbers are spiralling

Paris, France: Migratory freshwater fish populations crucial to river health and sustaining the livelihoods of millions of people are in freefall and...

Paris, France: Migratory freshwater fish populations crucial to river health and sustaining the livelihoods of millions of people are in freefall and risk collapse, a major UN assessment warned Tuesday.

Habitat destruction, overfishing and water pollution from the Amazon to the Danube threaten the very survival of hundreds of species whose epic voyages along the world's great rivers go largely unnoticed.

Freshwater fish face multiple threats, said the report published at the opening of the COP15 summit on migratory species in Brazil, making them "among the most imperilled vertebrates".

Populations of Mekong giant catfish, European eel and various sturgeon species are among those that have been decimated in recent decades due to man-made pressures that include the construction of dams and harvest for caviar.

Some -- including the Chinese paddlefish -- have already been declared extinct, while others are functionally reliant on captive breeding stock and reintroductions to support wild populations.