This dataset contains the results from quadrat surveys from 5 sites in Cockburn Sound, Perth, Western Australia. A survey was conducted in September 1994 to determine the biomass and distribution of filter feeders in relation to seagrass distributions. Macro-suspension-feeders biomass was high in Posidonia meadows and generally lower in bare sediment, although on bare sediment the introduced polychaete Sabella spallanzanii reached considerable biomass. Epifaunal feeders on Posidonia leaves reached a substantial biomass. Heterozostera and Amphibolis meadows appear to support a low biomass of macro-suspension-feeders and epifaunal feeders.