Indo-pacific humpback dolphin
Sousa chinensis
Max Size: adult males 350cm (230kg), newborns up to 100cm (20kg) They have strong geographical and individual variation: adults have been observed to be grey, white or pink; with mottled spotty patterns or solid colours - present a rather ragged appearance Calves are born dark grey or even black, slowly lightening to a mottled grey with age Males tend to retain more spots than females Characterised by their namesake: a humped back. They have a distinct dorsal fin and slight basal hump A long beak in comparison to their relatively small melon
Distribution
Original range occurred from Northern Australia; all through southeast Asia; all the way North up to East China and West towards East India. However they are now scarcely scattered across this range due to population decline mainly due to human threats
Usually inhabits bays, estuaries, mangroves and sandbanks - water shallower than 25 metres
Description
Max Size: adult males 350cm (230kg), newborns up to 100cm (20kg)
They have strong geographical and individual variation: adults have been observed to be grey, white or pink; with mottled spotty patterns or solid colours - present a rather ragged appearance
Calves are born dark grey or even black, slowly lightening to a mottled grey with age
Males tend to retain more spots than femalesCharacterised by their namesake: a humped back.
They have a distinct dorsal fin and slight basal hump and a long beak in comparison to their relatively small melon
Behaviour and Ecology
Travel in small pods, usually less than 10 individuals - largest group size recorded was 44 individuals
A relatively shy species - hardly seen interacting with boats - sometimes observed following trawlers and travelling with bottlenose dolphins and Irrawaddy dolphins
Diet: small fish and cephalopods
Adults often present a pink colour due to blood vessels close under the skin for thermoregulation
Main Threats
Coastal development
Due to their coastal range, populations tend to occur around developed densely populated urban areas with many ongoing land “reclamation” projects which pose both water and sound pollution threats as well as heavy vessel traffic.
A perfect case study on the impacts of coastal development is the Hong Kong population.
Bycatch
Their habitat tends to overlap with fishing hot spots in SE Asia - bycatch and accidental entanglement is the leading cause of death in coastal HBD populations
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Fun facts
The Cantonese language has the old phrase “wu gei bak gei” which refers to someone or something as a nuisance or a bad omen. This originated from fishing culture as the humpback dolphins would steal fish from their nets. The modern word for dolphin “hai tun” literally translates to “sea pig”.
