The aim of this study was to describe the dynamics of GABA on natural Haliotis settlement surfaces in order to evaluate the role of GABA as a natural settlement inducer. Production and consumption of GABA on the hard surfaces of the coastal marine abalone settlement habitat, particularly on crustose red algae (CRA), are described. It is concluded that in the typical New Zealand Haliotis settlement habitat, GABA is not likely to play a significant role as an inducer of abalone larval settlement because on the preferred settlement surfaces it is not readily produced from its precursors but it is easily degraded.