Social Organisation, Behaviour & Life History
Indo-Pacific finless porpoises typically occur in small groups, generally consisting of 3 animals or fewer. Group sizes tend to be slightly larger in spring, while they decrease in autumn. Although aggregations of up to 20 porpoises can be observed, these gatherings are characterized by very loose associations.
Finless porpoises primarily feed on small fish, squid, and shrimp found in coastal waters. The most common and numerically significant prey species is the cephalopod (Loligo sp.), followed by the lion-head fish (Collichthys lucida) and the tiger-tooth croaker (Otolithes argenteus).
Life History
They are approximately 70 cm in length at birth. As adults, they can grow up to 170 cm and weigh as much as 70 kg. They typically reach maturity between the ages of 4 to 6 years. The oldest recorded finless porpoise stranded in Hong Kong was about 33 years old.