The adult population of the western rock lobster predominantly reside in offshore limestone or coral reefs along the Western Australian coast, from North-West Cape, to Cape Leeuwin (Bellchambers et al. 2012). Monitoring of commercial catch and specialised pot surveys indicate that the majority of the breeding population are found between 35 and 75 m (20 and 40 fathoms), with only a small proportion found in waters less than 35 m water depth (Chubb et al. 1989, de Lestang et al. 2016). Due to the depth of water they reside in, significantly less is known about habitat use of adult western rock lobster compared with juveniles. However, there is no distinction between the habitat use of juveniles and larger juveniles or sub-adults in the shallow water juvenile habitats. It is therefore highly likely that adult habitat use is similar to that of juveniles; diurnal in nature, occupying ledges and crevices in the reef during the day, and foraging in seagrass and kelp at night. It is highly likely that this behaviour is mirrored in the deep water habitats typical of adult lobsters.
A significant portion of the deep water habitats within the adult western rock lobster distribution has been mapped to describe both the physical substratum and the associated biological communities (Bellchambers et al. 2012). Overlaying these maps with fishing effort and catch indicates that lobster distribution is correlated with reefs, reefs with kelp, and sessile invertebrate habitats consisting of sponges on sandy or gravel substrates (Bellchambers et al. 2017). At a finer scale, habitat modelling indicates that within these suitable broad-scale habitats, adult lobster distribution is related to the availability of fine-scale mixed habitats, or geomorphic complexity, which is likely related to the presence of high-quality shelter and food resources (Hovey et al. 2012). There is evidence that within these deep water habitats, habitat use is size-dependent, with larger lobsters being associated with mixed assemblages containing sponge, and smaller lobsters with mixed assemblages containing Ecklonia sp. (kelp) (Bellchambers et al. 2010). However, recent research has indicated that within a pot large lobsters may deter smaller lobsters from entering (Tuffley et al. 2021), and therefore the absence of the smaller animals in the sponge dominated habitats may reflect this behaviour rather than differing habitat uses.