While the 20 or so dolphins inhabiting the Swan River may not have their own Facebook page just yet, they do have their own FinBook.
Murdoch University researchers recently released the second edition of FinBook, the annual photographic guide to Perth’s iconic river dolphins.
The latest catalogue shows the dorsal fins and biographic details for more than 20 dolphins regularly observed within the Swan, including five dependent dolphin calves. The dorsal fin of each dolphin has a unique set of scars and other markings that function like ‘fin-prints’ for identification.
This version of FinBook also offers insights into the social relationships dolphins maintain, including long-term alliances among males.
Murdoch University dolphin expert Dr Hugh Finn, who, along with fellow researcher Delphine Chabanne, developed the dolphin content for this edition of FinBook, said seven of the dolphins have been resident in the river since at least 2001 when dolphin research in the estuary began.
“This year, we organised FinBook so that the dolphins all appear among their known associates,” said Dr Finn from the Murdoch University Cetacean Research Unit.
“Like humans, dolphins are very social animals and tend to have long-term associates – so if you see one of these dolphins it is likely their associates will be nearby.”
Images of the dolphins were taken over the last year by Ms Chabanne as she monitored their activities over the year. Her research is part of the Coastal and Estuarine Dolphin project.
All of the river dolphins also spend time in coastal areas outside the Riverpark, sometimes venturing as far as Cockburn Sound to the south and Gage Roads to the north. The resident dolphins are unique in that they use the Riverpark on a daily or near-daily basis year-round.
Dr Finn said foraging for food was their main activity, and wherever the dolphins were sighted in the river usually reflected the availability of prey like mullet, herring and whiting.
The five calves seen during the year are Highhope (the youngest, born in July last year), Soul, who is slightly older, and Night, Gizmo and Zari who are aged two to three years.
Finbook is a joint initiative of Murdoch and Curtin universities and the Swan River Trust. It was first launched in May 2011. The new edition was unveiled on Wednesday , June 27, at a reception for hundreds of trained Dolphin Watch volunteers who report their dolphin sightings to the Trust to assist research by the two universities.
Swan River Trust principal scientist Dr Kerry Trayler said the Swan and Canning rivers were an important habitat for bottlenose dolphins.
“It’s a place where they bring their calves and come to socialise and feed, so maintaining good water quality and ecological health is essential to protect their food resources,” she said.
FinBook is available here.