A Giant fish is declared extinct — how do scientists conclude that?

News: Chinese researchers, based on the Red List criteria of the International Union for Conservation of Nature (IUCN), have concluded that Chinese Paddlefish are extinct.

Facts:

• Chinese paddlefish, also known as the Chinese swordfish lived in Yangtze River in China. It dates back 200 million years.
• The researchers estimate that it became functionally extinct by 1993, and extinct sometime between 2005 and 2010.

Additional Information

Categories of Extinction by IUCN:

1.       Extinct in the wild: a species survives only in a captive environment

2.       Locally extinct: species has ceased to exist in a particular area but may exist in other areas.

3.       Functionally extinct: the species continues to exist but it has too few members to enable it to reproduce meaningfully enough to ensure survival.

4.       Globally extinct: a species has no surviving member anywhere.