Population characteristics of the abalone Haliotis roei on intertidal platforms in the Perth metropolitan area

Abstract

Basic population characteristics of the commercial abalone species Haliotis roei are compared on a heavily fished intertidal platform and a platform with no fishing pressure. Seasonal and annual variations in population density were large on both platforms, though densities were lower on the fished platform (Trigg) than the unfished area (Waterman). Most abalone at Waterman were adults of 2+ years (>60 mm), while few animals of this size occurred at Trigg. There were not sufficient adults at Trigg for reproduction on the platform to replenish the population, and it is postulated that replenishment comes from larvae originating from adjacent platforms. A subtidal rock with an unfished population of H. roei recovered at a rate of only about 10% per year, suggesting that heavily overfished populations would recover slowly, if at all.