The Indo-Pacific Humpback Dolphin
About the dolphins
Scientific name / family
Sousa chinensis / delphinidae
Description
The Indo-Pacific Humpback dolphin gets its name from the elongated dorsal fin and humped back appearance which arises from the accumulation of fatty tissue on their backs as they age. They also differ from other dolphin species in relation to their mounded forehead and long beaks.
Male and female Indo-Pacific Humpback Dolphins grow to a length of between 2.6m and 2.7m reaching physical maturity at around 14 years of age (sexual maturity occurs between the ages of 10 to 13 years). In the wild, these dolphins will live to around 40 years of age. Indo-Pacific Humpback dolphins can weigh up to 260kg but more commonly weigh around 200kg.
Skin colours will vary depending on location and age with calves being born grey and lightening with age (particularly the dorsal fin and forehead). Chinese dolphins turn pink as they age.
Distribution
Indo-Pacific Humpback dolphins are distributed from the coast of Africa, the Arabian Sea, Indian waters and beyond to the South China Sea. In Australia they inhabit the tropical waters of the west and east coasts and are classified as rare by the EPA and ‘near threatened, population decreasing’ by the IUCN Red List of Threatened Species.
Habitat
Indo-Pacific Humpback dolphins prefer coastal and estuarine habitats in tropical and sub-tropical regions where waters are less than 20m deep. In our region, this area extends from the The Great Sandy Strait to the Tin Can Inlet. They are not known to be migratory.
Diet
The dolphins live on a diet of fish, prawns, molluscs, crabs, squid and octopus according to the location and season.
Behaviour
Indo-Pacific Humpback dolphins are more leisurely swimmers than some other dolphin species and do not as a rule surf bow waves. They swim in small pods of around five or so dolphins. Each pod is lead by an alpha male, or, on occasion, an alpha female. Males will have raking marks on their bodies from fights with other males over territory, and/or female members of its pod.
Threats
Living close to coasts and rivers, the The Indo-Pacific Humpback dolphin is especially susceptible to pollution as well as shark and fishing nets. Other threats include overfishing of their habitat, noise pollution affecting their sonar location, marine activities, harrassment and coastal development. They have nowhere to go when their environment is damaged.
History of the Tin Can Dolphins
We are often asked “how did these dolphins come to interact with the locals at Tin Can Bay”? It started back in the 1950’s when an injured dolphin beached himself on the sand at Barnacles Cafe. The locals took pity on him and started to feed him. This dolphin was well battle scarred and became known as ‘Old Scarry’. Once he was well enough Old Scarry returned to the wild but regularly returned to the bay to visit the locals and enjoy a free meal.
The second well known dolphin at Tin Can Bay was a female, also called Scarry. In 1991, there was much excitement when Scarry arrived in the bay with a calf. The local school children named this one ‘Mystique’ who continues to visit the bay on a daily basis as the third generation to carry on this tradition.
Mystique is the alpha male of his pod and is also scarred from his many battles, including a battle with a bull shark in December 2007. Once again a dolphin sought refuge in the cove at Barnacles with volunteers feeding and caring for him around the clock for 10 days. Once he was able to hunt for himself, Mystique thanked everyone with an aerial display before heading out with Patch to return to the wild.
Patch is a female member of Mystique’s pod who started to come into the Cove to feed after the disappearance of Scarry. She is thought to be in her mid twenties and weigh just over 200 kg. In comparison to Mystique she has very few battle scars and she is throwing a pink colour as she ages.
More recently another young dolphin known as ‘Harmony’ began visiting regularly with Mystique. Harmony is a juvenile male thought to be about five years old. This makes the fourth generation of dolphin to feed with the locals and visitors to Tin Can Bay. Harmony is also quite scarred for one so young and appears to be holding up the family tradition of liking a good fight. Harmony is very inquisitive and likes to check out his human visitors from a distance.
A note for those venturing out on the water
Indo Pacific Humpback dolphins are shy dolphins so it is a rare privilege to interact with this species so closely. We would like to remind people that feeding these dolphins from a boat is illegal, but more importantly it encourages them to pursue boats which can cause injury for an inexperienced dolphin. The quality of the fish is also very important and contaminated fish can be dangerous to the health of the dolphins.
When boating in the Tin Can Bay area, admire our dolphins from a distance while out on the water or come and visit us at the Dolphin Centre if you would like to feed them.
The maximum penalty for intentionally feeding (other than permitted feeding programs) or touching a dolphin is $8,000. The maximum penalty for approaching a dolphin to within less than 100m (300m for jet skis) is $12,000.