Among the early historical observation of shellfish being cooked and eaten, and scattered around the huts, there are few descriptions of shellfish collecting. However, the few observations that mention the gender of the collector or carrier of the shellfish indicate men as well as women were involved in collecting shellfish in the Sydney region.

Shellfish were collected by hand from rock platforms as well as the sandy and muddy intertidal shorelines of the coast and estuaries. In Botany Bay Captain Cook saw people were in canoes collecting shellfish by hand from the sand and mud banks in shallow waters.

Oysters (probably both mud and rock oyster, though this is not specifically stated), mussels, cockles and limpets were the only species named. The local names of only a few shellfish were recorded: Dal-gal mussel, Dotang-by a rock oyster, Dainia oyster, and Kah-dien 'the shell on the wo-mar-ra or spearthrower', which could be one of several cockles.

Analysis of the shell species found in excavated shell middens indicate that people living around Sydney Harbour, Botany Bay and Broken Bay, most commonly ate Rock Oysters Saccostrea glomerata, Hairy Mussels Trichomya hirsuta and Sydney Cockles Anadara trapezia. Mud Oysters Ostrea angasi and Hercules Club Whelks Pyrazus ebeninus were also relatively common.

Along the ocean coastlines, there is a greater range of shellfish in the shell middens. Limpets Cellana tramoserica and Black Nerita Nerita atramentosa are the most common species, with Cartrut Dicathais orbita and Turbans Turbo torquata and Turbo undulata and Spengler's Triton Cabestana spengleri being less common.

In shell middens in the lower parts of Sydney Harbour, Botany Bay and Broken Bay, where ocean conditions exist, both estuarine and ocean species are present.

People living along the upper brackish parts of the Georges and Hawkesbury Rivers were reported to have eaten teredinid or Teredo. Although commonly called shipworms they are a shellfish and not a worm. They are also known as cobra, a name from the local Aboriginal name, cah-bro. They are a marine wood-borer which inhabit trees and logs that have fallen into the water and remain submerged, preferably in still water.

After a trip to the Hawkesbury River (Richmond Hill) in 1790s, Judge Advocate David Collins wrote that a man left

'behind him a specimen of his food and the delicacy of his stomach; a piece of water-soaked wood (part of the branch of a tree) full of holes, the lodgment of a large worm, named by them cah-bro, and which they extract and eat' (Collins 1798[1975]:462)

Collins continued with reference to groups living on the Georges River:

'There is a tribe of natives dwelling inland, who, from the circumstance of their eating these loathsome worms, are named Cah-bro-gal.'

The present-day Sydney suburb Cabramatta is named after this area.