A computer simulation was conducted to study the effects of densities, abundances, and aggregations of adult abalone populations on the fertilization success (amount of fertilization per spawning female). Impacts of densities were examined by having different numbers of adult abalone in spawning grounds of the same size. Impacts of abundances were studied by having different numbers of adult abalone in spawning grounds of different sizes with constant densities. Impacts of aggregations were investigated by having different spatial distributions for adult abalone with constant densities and sizes of spawning grounds. The fertilization success increased with the adult density, and the rate of increase in the fertilization success decreased with increasing densities, exhibiting a typical Allee effect. If the density remained the same for a single population, changes in the adult abundance had minimal impact on the fertilization success unless the abundance was really low. Adult aggregation would only considerably increase the fertilization success at relatively low adult densities. The fertilization success was greater for a large population than the combined fertilization success for two smaller and isolated populations with the summed abundance of the two small populations equivalent to the abundance of the large population.