Good and bad fishing areas for Haliotis laevigata: A comparison of population parameters

Abstract

On the southern coast of Western Australia, proportionately more reproductive specimens of greenlip abalone, H. laevigata, were of legal size in 'good' fishing areas than in 'bad' fishing areas. Sex ratios were usually 1:1. Maturation of the gonads began at a size of 70-90 mm shell length (SL) and by 100-110 mm SL all animals were reproductively mature. Size-specific fecundities were not statistically different among the four good fishing areas examined, nor were they between the two bad fishing areas, but size-specific fecundity was greater in good than in bad fishing areas. Spawning begins as soon as the animals are mature; there is no gap between apparent histological maturity and actual spawning. Gonads are quiescent in the first part of the calendar year. Development is rapid in August and September, when animals begin to reach ripe condition. A maximum proportion of ripe animals occurs in October and November, followed by spawning in December.

There was no difference between growth rates of males and females in either the good or the bad fishing areas. The von Bertalanffy growth equation disclosed no difference in growth between good and bad fishing areas, but close inspection of the data suggested that slower growth did occur in the bad fishing areas. The abalone reach reproductive maturity at an age of 2.5 to 3 years and the legal size of 140 mm SL at 5 to 6 years.