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12 Oct 2020

Dolphin ‘signature tune’ study gains momentum

Dave Savides (Zululand Observer)

The ongoing humpback dolphin study at Richards Bay is heading into ‘sound’ new territory. Not only has a new hydrophone (underwater microphone) been installed, but the recordings it captures will add greatly to an acoustic study destined to shed new light on how dolphins and other cetaceans communicate with their own kind.

For a number of years, a hydrophone, nicknamed ‘Jingles’, located off Newark Beach at Alkantstrand, has faithfully recorded the sounds of passing dolphins and whales. Jingles has been pensioned off and has been replaced by ‘Sonique’, thanks to the generosity of Austrian dolphin devotee, Judith Leiter. She has become an integral part of the local research, which is headed by marine biologist, Shanan Atkins, of Wits University.

The research, which mainly entails dolphin dorsal fin identification from photographs – currently being enhanced through the use of an algorithm-based ID system – entered a new phase earlier this year. A team of environmental scientists spent time following the humpbacks in the Bay area, and recording their vocal repertoire, hoping to identify potential signature whistles.

With Shanan on the expedition were Natasha Shilubane of Wits University, plus Dr Tess Gridley, Sasha Dines and Katie Keanly, all of Sea Search at Stellenbosch University.

‘With Sonique now installed, we are going to build on the info we have, as well as acoustics and photos taken since 2017,’ said Shanan.

‘Natasha has spent time going through the hundreds of photos of humpies taken at the dolphin viewing platform by our man on the scene, Dave Savides.

‘Judith has logged the dates and times they were seen, and we have given Natasha our recordings that corresponded to those times. She is now working through these, looking for whistles, which she will use to determine whether or not humpback dolphins are emitting signature whistles.’

 

Whale songs
Shanan said they had also shared data with whale song researchers in the southwestern Indian Ocean through Yusuf Suliman of DHL, who unhesitatingly assisted in getting the data to Reunion.

‘As we study endangered humpback dolphins at Richards Bay, recording their underwater sounds, we also hear the sounds of whales that migrate past Richards Bay, and we share these with their scientists,’ she said.

Shanan had special praise for Judith, who connects with the Bay humpies via her computer at the foot of the Austrian Alps.

‘She conducts surveys, watching for dolphins and whales for hours and is really quick to take screenshots. She records the dolphin sightings meticulously: hers, Dave’s and all the additional reports we receive.

‘She plots all the video sightings on a map, and writes sighting reports for the Society for Dolphin Conservation, and for our Facebook page. She is full of positive words and encouragement.’

Other contributors to the research include Richards Bay resident Rodger Doust, a volunteer citizen-instrument-scientist who looks after the equipment, as well as the beach management team, the lifeguards and the Sharks Board.