Two species of resident dolphins are to be found inshore along the Victorian coastline. DRI has been monitoring the resident populations of bottlenose dolphins in Port Phillip, Western Port and the Gippsland Lakes since the early 1990s. More recently, DRI made an unusual discovery of a small resident population of common dolphins close to the southeastern seaboard of Port Phillip.
Victoria’s bottlenose dolphins (Tursiops cf.australis) are resident to Port Phillip, Western Port and the Gippsland Lakes with other small resident groups likely to be found along the open coast of Victoria. Long term population studies by DRI suggest there may be between 100 and 120 individuals living in Port Phillip and around 50 -70 individuals residing in the Gippsland Lakes with seasonal abundance at this location increasing during the winter months. The Western Port bottlenose dolphins are yet to be properly studied so population numbers are not well understood. Bottlenose dolphins found in Victorian waters are distinctly different in their appearance compared to the larger offshore bottlenose dolphin found in nearby waters. They also appear subtly different to other coastal bottlenose dolphins found around Australia. At maturity, males are larger than females.
Length – 2.6 - 2.8 metres
Weight – 200 – 240 kilograms
Appearance–Dark grey dorsally, fading to a lighter grey on the flanks (sides) then lightening to a cream to white colouration on the lower flank to ventral side (belly). Other features include a light grey ‘brush stroke’ patterning sweeping up toward the dorsal fin from the flank as well as a pale colouration around the eye. The rostrum (beak) is relatively short and the dorsal fin is large and falcate (curved). Unlike other coastal bottlenose dolphins, Victoria’s resident dolphins do not typically have spots on the belly.
Short-beaked common dolphins
Common dolphins (Delphinus delphis) around Victoria are mostly limited to offshore waters, so the discovery of the small resident community off the south eastern seaboard of Port Phillip makes these particular animals very special. Studies led by DRI since 2007 have shown this resident group of common dolphins to be comprised of only around 30 individuals, mostly made up of females, juveniles and calves.The resident common dolphins of Port Phillip appear noticeably smaller than the offshore common dolphins found in nearby Bass Strait. As with the resident bottlenose dolphins, at maturity, males are larger than females.
Weight – approximately 80 – 150 kilograms
Appearance–Dark brown to grey dorsally (back), yellow/gold along the forward flank (side) changing to a light grey toward the tail. The ventral side (belly) is typically white. The merging of the colours along the flank of this species forms an hourglass patterning. The rostrum (beak) is relatively long (noticeably longer than that of the bottlenose), narrow and tapered. The dorsal fin is smaller and more triangular than that of the bottlenose dolphin.