Surveys of the ecological use of epibenthic habitat by fish in the central Great Barrier Reef using baited remote underwater video stations (BRUVS (TM)) (FRDC Project No. 97/205)

BRUVS (TM) were deployed at spatial coordinates known, from previous major studies using fish traps, to be "hot-spots" for the families Lutjanidae (sea perches), Lethrinidae (sweetlip emperors) and Serranidae (coral trout and cod).BRUVS (TM) were deployed at depths between 30 and 70 m in three mid-shelf locations (Davies Reef (9), Kelso Shoals (18), Rib Reef (9)) and in both shallow and deep inshore locations (Calliope Channel (14), Curacoa Channel (27), and Robbery Shoals (3)).Replicate BRUVS (TM), were deployed in daylight hours and the time, depth, latitude and longitude was recorded for each set.Interrogation of each tape provided:- a classification of the habitat at each set, based on estimated sediment composition and/or the nature of epibenthos- the time the BRUVS (TM) settle on the seabed (TOB)- the time of first sighting of a taxa (TFS)- a coarse classification of 'Adult' or 'Juvenile' for these taxa based on size and shape- the time of first feeding of taxa (TFF) in the field of view,- the maximum number of each taxa seen together, or readily identifiable, in any one time on the whole tape (MaxN),- the time at which this maxima occurred (TMaxN)- the behaviour of each taxa toward the bait (passing, scavenging, or feeding), and- the time at which all bait was exhausted if such an event occurred.The habitat categories recognised were: megabenthos, Sargassum, Halimeda, low algae, mud, fine sand, coarse sand, rubble, and 'near benthos'. The 'near benthos' category covered sets where video units landed on sand, but in the far field of view, or during the deployment or retrieval, significant patches of rock or megabenthos were seen.Image grabs also allowed size estimates of fish directly above the scale grid on the bait canister. Baited remote underwater video station (BRUVS (TM)) surveys were undertaken to investigate the relationship between fish requirements for food and shelter and the distribution of sponge, gorgonian and algal 'megabenthos'.The specific questions addressed were:1. what is the nature of fish communities inside and outside megabenthos patches?2. what benthos and sediments characterise some known 'hotspots' for inter-reef lutjanids?The results of the BRUVS (TM) surveys were compared with concurrent RUVS (unbaited) surveys, trapping and underwater visual census (UVC) as methods to census demersal fish. This research was a component of subproject 8, "The ecological usage of epibenthic habitat by key commercial finfish species", of the Fisheries Research and Development Corporation Project No. 97/205, "Dynamics of large sessile seabed fauna, important for structural fisheries habitat and biodiversity of marine ecosystems - and use of these habitats by key finfish species"