Which shellfish were most common in the Bay before Melbourne was born?

I figure that shell middens created by indigenous people over thousands of years  probably give the best available clues. Aboriginal Affairs Victoria have very kindly sent me an Archaeological Survey of the Mornington Peninsula (Sullivan 1981). This records 15 shell species present in 98 middens on the Port Phlliip Bay coast (south of Canadian Bay Road) .

The most common species in practically all middens was the Blue Mussel Mytilus planulatus. It appears they were the most common species on rock platforms around the bay, and a favourite food for the Boon Wurrung people whose traditional land extends from Werribee River, right around the east coast of the Bay and to Wilsons Promontory. The study found Mytilus edulis planulatus is the dominant species on all Mornington Peninsula middens.  Subninella undulata, Cellana tramoserica, Notohaliotus ruber, and Dicathais orbita are present in more than 50% of the sites in small numbers. ”

But how are these once common species travelling now? If anyone is the full bottle on the life an time of mussels in the Bay, or even just  interested in the topic, Baykeeper would love to hear from you.