The influence of artificial reef structural complexity on fish assemblage composition

built artificial reefs (ARs) are becoming an increasingly popular tool for enhancing recreational fishing activities. This study examined the establishment of fish assemblages at a new AR site in the Exmouth Gulf, Western Australia (King Reef). A remotely operated vehicle fitted with stereo-video (stereo-ROV) was used to survey the fish assemblages associated with four different artificial reef modules (Fish Towers, Apollos, Abitats, and Pyramids). The observation of recreationally targeted species at the AR provides evidence of its potential to contribute to local recreational fisheries. There were differences in the fish assemblages associated with the different modules with the Fish Towers (large subsurface steel buoys) having the highest mean fish abundance and biomass. The design of the modules that are incorporated into an AR design have a considerable influence in shaping the assemblage and biomass of fishes at an AR site. Some differences between module types were not immediately obvious due to the close spacing of modules which created a relatively contiguous fish assemblage across the whole reef field. These results indicate that the characteristics of purpose-built structures that influence the associated fish assemblage can be manipulated to create a design that can fulfil a specific purpose, such as promoting the recruitment and attraction of targeted species to enhance recreational fishing opportunities. • Fish assemblage composition varied across different artificial reef modules. • Higher fish abundances were associated with greater vertical relief and complexity. • Structural characteristics influence abundance of recreationally targeted species. • Artificial reefs should be designed to fulfil the reef's intended purpose.