Context

One of the largest freshwater fish has been declared extinct in a study published in the journal Science of the Total Environment.

About

• The Chinese paddlefish (Psephurus gladius) was an iconic species, measuring up to 7 m in length, dating back from 200 million years ago, and therefore swimming the rivers when dinosaurs ruled the Earth.
• Its ancestral home was the Yangtze River.
• Chinese researchers made this conclusion based on the Red List criteria of the International Union for Conservation of Nature (IUCN).

The Red List has several categories for extinction

• “Extinct in the wild” means a species survives only in a captive environment
• “Locally extinct” means a species has ceased to exist in a particular area but may exist in other areas.
• “Functionally extinct”, which means the species continues to exist but it has too few members to enable to reproduce meaningfully enough to ensure survival.
• “Globally extinct”, it means a species has no surviving member anywhere. Such a conclusion is reached when there is no reasonable doubt left that its last member has died.

Other facts

• Declaring a species extinct is an elaborate process. It involves a series of exhaustive surveys, which need to be taken at appropriate times, throughout the species’ historic range and over a time-frame that is appropriate to the species’ life cycle and form.
• Once declared extinct, a species is not eligible for protective measures and conservation funding; therefore, the declaration has significant consequences.
• In the case of the Chinese paddlefish, the researchers made the conclusion over long-term surveys. It was once common in the Yangtze, before overfishing and habitat fragmentation — including dam building — caused its population to dwindle from the 1970s onwards.
• Between 1981 and 2003, there were just around 210 sightings of the fish.
• The researchers estimate that it became functionally extinct by 1993, and extinct sometime between 2005-2010