Dolphin calf found dead
CAUSE OF DEATH UNKNOWN
A DEAD male dolphin calf was found washed up on South Perth foreshore last Wednesday, reiterating the fragility of the newborn mammals.
In a herculean effort, the dolphin’s mother, Tupac, kept her baby afloat for more than two days, swimming more than 20km up the Swan River from Fremantle’s Fishing Boat Harbour.
Murdoch University Cetacean Research Unit PhD candidate Delphine Chabanne said the mortality rate for baby dolphins aged less than six months was more than 50 per cent. Two calves died in the Swan Canning Riverpark last year.
Ms Chabanne, who featured in the Gazette’s frontpage story last week about the potential impact of human behaviour on Perth’s river dolphin population, said it was not a good start to the year.
She could not be sure if the calf was stillborn or died not long after birth, if its injuries were caused by boat strike or by Tupac trying to keep her calf afloat.
Tupac was seen keeping her calf afloat in Fremantle’s Fishing Boat Harbour at 5.30am on Monday and again near the Causeway in the Swan River – a distance of more than 20km – the following day.
“Tupac was seen carrying her dolphin on her rostrum (snout), trying to make it swim,” she said.
“She had been trying to do that for at least two days which is amazing.”
Summer and autumn is calving season for the riverpark’s 25 resident dolphins.
Tupac, the mother of Gizmo, was first recorded in 2001 and is believed to be more than 20 years old, one of the population’s oldest members.
Ms Chabanne said she was not surprised Tupac was pregnant as Gizmo, a male, had recently become more independent.
He suffered a fishing line entanglement in April 2012 that almost severed his dorsal fin.
Water Police officers were able to free him two months later.