Confirmation of a relationship between the localized abundance of breeding stock and recruitment for Haliotis rubra Leach (Mollusca: Gastropoda)

The hypothesis that for Haliotis rubra Leach the localized abundance of mature abalone determines the abundance of recruitment was tested with experimental reductions of breeding stock at four sites. At each site there was an experimental area 60 m in length, from which adult abalone were removed, and two control areas 60 m either side of the experimental area. The abundance of recruitment was found to vary significantly between the four sites and between control areas within three of the sites. Observations which are consistent with recruitment being highly localized. The overall density of recruitment to the experimental areas was significantly lower than in the control areas indicating that the abundance of breeding animals determines the abundance of recruitment. When these data were combined with data from the studies of Prince et al. (in press) for the same sites, a relationship between breeding stock and recruitment is clearly evident, confirming that the density of breeding stock was the major determinant of recruitment abundance. These results show that for this species, on a spatial scale measured in 10s of meters, the abundance of recruitment is directly related to the abundance of mature abalone.