Recruitment variation in sympatric populations of Haliotis rubra (Mollusca. Gastropoda) in southeast Australian waters

Abstract

Recruitment of abalone Haliotis rubra was examined in sympatric populations off southeastern Australia soon after the main spawning period. The size range of post-settlement juveldes (recruits) collected from the reef surface was indicative of recent settlement. Recruitment was strongest after the main spawning period but episodic minor recruitment in some populations was also observed throughout each year. Recruitment varied significantly both between populations and for each population over time; the latter varied over 3 orders of magnitude. The highest number of H. rubra recruits in a sample (the area contained within a 1 m2 quadrat) was 12456. Abalone larvae can settle in densities much hlgher than has previously been assumed. Local~sed dispersal of larvae provides an explanation for our results. Variability in recruitment of H. rubra was high even when the density of the adult population was constant.