Effective carp control requires a fundamental understanding of carp abundance and biomass (total weight of carp in a given area) within representative habitats (i.e. rivers, lakes, billabongs, estuaries) and at appropriate geographic scales (local, river reach, river-basin, inter-basin). A collaborative project being undertaken by research agencies from across eastern Australia under the NCCP aims provide a robust estimate of carp abundance and biomass in a broad range of aquatic habitats, reaches and river basins across the country. We utilised historical catch data (carp relative abundance) supplemented with contemporary data collection in key sites to inform our biomass model. To convert relative abundance to total abundance, we undertook a range of capture-mark-recapture detection experiments in different habitat types across the eastern seaboard. Preliminary detection rates varied from 4% in large, lowland rivers, to 20% in small wetland habitats. Biomass estimates for different habitat types, and a combined total biomass/number of carp for Australia, will be presented.