Understanding the spatial distribution of demersal species and benthic biota is fundamental for identifying areas of ecological sensitivity and assessing the risks posed by fishing activities. Bioregionalisation approaches provide an efficient way to map community assemblages across large regions by grouping species according to shared environmental characteristics.
We characterised demersal fish and benthic biota into bioregions to inform an ecological risk assessment for the East Coast Prawn Trawl Fishery. Using a spatially balanced design, 227 standardised research trawls were conducted from Newcastle (NSW) to the southern Coral Sea (QLD). After retaining species occurring in more than 10% of samples, count data for 120 species of fish, crustaceans, and other demersal taxa were analysed using the Regions of Common Profile (RCP) modelling framework.
The RCP model quantified and mapped distinct species assemblages across eastern Australia, revealing seven well‑defined bioregions structured primarily by depth, latitude, and habitat. These results demonstrate that RCP provides a direct, quantitative method for classifying benthic communities at management‑relevant scales. The bioregions identified here offer a robust basis for assessing the ecological risk of trawl fishing and improving both fisheries management and spatial planning. We can use species specific risk conditional on RCP distribution, to identify bioregions that showed higher expected abundance for species of concern under the ecological risk assessment framework.