After Chinese sturgeons get released, how should we track them? There are four methods.

PIT tagging

A PIT tag is a small radio transponder that contains a specific code, which allows individual fish to be assigned a long-term digital number. The tag scanner releases a radio frequency which can be identified by the receiver when a tag is within range. This is the greatest advantage of PIT tagging.

Sonar tagging

A sonar tag, or acoustic fish tag, is surgically implanted or externally attached to a fish. The tag transmits a high frequency "ping" which can be heard by receivers strategically placed around the area. It can calculate travel time and the location of the fish.

T-shaped tagging

A T-shaped Tag is anchored into muscle or bone at the base of the dorsal fin. It contains identification information of the fish such as ID and phone number. If the Chinese sturgeon is caught by fishermen, they can contact the researchers.

DNA tagging

A small number of Chinese sturgeon fin samples are taken to extract their genetic information. The researchers then build a DNA information library to know their family trees.

Check out the series "Little Secrets of Chinese Sturgeon" to find out more about this critically endangered species.

For more: 

The Chinese sturgeon: A critically endangered species

The Chinese sturgeon: 'King of freshwater fish' can live 100 years

The Chinese sturgeon: A fish with 'family planning policy'

10,000 Chinese sturgeons released into Yangtze River

(Cover designed by CGTN's Jia Jieqiong. Video by Lu Zhongcan and Liang Siyan from China Three Gorges Corp.)

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