What is photo-identification (photo-id)?

AFCD has been monitoring the distribution and abundance of Chinese white dolphins (Sousa chinensis) in Hong Kong for the past 10 years.

During the course of monitoring, photographs of dolphins are taken and catalogued.

Photo-identification involves taking photographs of unique markings on the dolphin's back and dorsal fin (such as nicks, scars and distinctive colour patterns) and matching these photographs to the photo-id catalogue. These markings are like human fingerprints and can be used for identifying individual dolphins.

Photo-id is a tool for studying the behaviour of individual dolphins as well as understanding their movements and reproductive patterns.

This method has been extensively used elsewhere to study dolphins and whales.