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Port Phillip Common Dolphins – Social Research Published

Congratulations to Dr. Suzanne Mason for her paper on the social structure of Port Phillip’s common dolphins, just published in the prestigious peer-reviewed journal, Marine Mammal Science. 

DRI supported Dr. Mason’s Honours and Ph.D. projects over almost a decade. During that time she also managed DRI’s research programs and contributed significantly to our education and community programs.

These projects confirmed the residency of the common dolphins (Delphinus delphis) in Port Phillip and now in this new paper, their unique social structure.  

Dolphins are no different to us in the sense that they form closer bonds with some individuals more than others. 

The challenge to figure this out with dolphins is that we can’t track their friends and connections on Facebook or LinkedIn! 

Instead, we take thousands of photos of dorsal fins, which enable us to ID individuals and the other dolphins they are seen with at the same time. Quite sophisticated analytical tools help to understand the strength of associations. 

The paper closely assesses the relationships with 12 of Port Phillip’s common dolphins. It shows that Tall Fin (9001), Esther (7000), and Ragged Fin (10102) are frequently seen together. Poke (1104) and V-Nick (0000) also seem to have a close association.  Similarly, Almost Clean Fin (8000) and Square Notch (10001) are quite often seen together, but not as much with other dolphins.  

The key finding from the paper is that Port Phillip’s common dolphins seem to have a much tighter and close-knit social structure than the same species in larger and open ocean groups. Maybe smaller groups need stronger relationships between individuals to survive?  

This work significantly adds to our understanding and is based on surveys between 2007 and 2014. 

Surveys since then show that V-Nick has had a calf in 2019, Ragged-Fin a calf in 2020, Poke calves in 2015 and 2020. So they are all doing well. 

Square Notch’s calf suffered an injury to its dorsal fin in 2012, has healed but with substantial scaring. We called it “DD” for damaged dorsal fin and it is regularly seen with the Bay’s growing common dolphin community.    

A great way to support our work is by joining supporters of our Adopt-A-Dolphin program. Many have been with us for over 20 years. You can choose your own dolphin from V-Nick, Tall Fin, Poke, and DD.

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