Restricting feed ration has more effect than diet type on the feeding behaviour of greenlip abalone Haliotis laevigata J.J. Buss a , D.A. Jones a , A. Lumsden b , J.O. Harris a,c , M.S. Bansemer a and D.A.J. Stone a,c,d,e * a School of Biological Sciences, Flinders University, Adelaide, Australia; b School of Earth and Environmental Sciences, University of Adelaide, Adelaide, Australia; c Marine Innovation Southern Australia, Adelaide, Australia; d Aquaculture Nutrition and Feed Technology, South Australian Research and Development Institute (SARDI), Aquatic Sciences Centre, Henley Beach, Australia; e School of Animal & Veterinary Science, University of Adelaide, Roseworthy, Australia (Received 9 July 2014; accepted 15 November 2014) Abalone farmed in Australia are predominantly fed formulated feeds, while in the wild, their diet consists of a mix of macroalgae. Here we investigated the feeding behaviour of juvenile greenlip abalone, Haliotis laevigata; fed live macroalgae and formulated diets at different rations; and observed their feeding behaviour using a novel ventral video monitoring technique. Four different diets (commercial chip, experimental flake, Ulva sp. and Gracilaria cliftonii) at two feeding rations (excess vs. restricted) were tested. Diet type had no effect on abalone movement, but macroalgal diets resulted in higher feed intakes. Restricting feed rations induced greater movement. Abalone moved little during the light period and moved mostly during darkness, except for animals on the restricted feed ration where feeding commenced during the light period. On farms, this phenomenon may be a useful behavioural indicator for identifying underfed abalone. Despite their lower intake, formulated diets promoted higher energy and nutritional intake, indicating that quantity of feed consumed is not solely indicative of nutritional gain. From a research perspective, the novel ventral monitoring method has created opportunities for further behavioural studies in molluscs. Keywords: greenlip abalone; Haliotis laevigata; aquaculture; formulated diet; macroalgae; feed ration; feeding behaviour; novel video monitoring Introduction In the wild, juvenile abalone feed on diatoms before transferring to a range of different macroalgae species as they mature to adults (Tutschulte & Connell 1988; Stepto & Cook 1993; Naidoo et al. 2006). Abalone show feeding preferences for specific macroalgae species, with some red algae being highly favoured by a variety of abalone species, particularly Australian temperate species (Shepherd 1975; Tutschulte & Connell 1988; Shepherd & Steinberg 1992). The green algae, Ulva australis, was shown to be of second preference or sometimes avoided in the wild by the same abalone species (Shepherd 1975; Fleming 1995). Despite the preference for specific types of macroalgae, formulated feed has been used exclusively in Australian land-based abalone *Correspondence author. Email: david.stone@sa.gov.au © 2014 Taylor & Francis Marine and Freshwater Behaviour and Physiology , 2015 Vol. 48, No. 1, 51–70, http://dx.doi.org/10.1080/10236244.2014.990701