ASFB Home > 2003 > Biological Invasions: Consequences for Parasites, Pathogens, Emerging Diseases, and Fisheries in the Marine Environment.

Density dependent reproductive investment in the greenlip abalone, Haliotis laevigata.

Luke A. McAvaney

Zoology Department, University of Melbourne, Parkville, 3010, Australia.
Email: l.mcavaney@ugrad.unimelb.edu.au

For species that are commercially harvested, it is especially important to understand the determinants of reproductive rate such that fisheries models are based on the best available data. This study examined the effect of density on the gonad development of adult greenlip abalone (H. laevigata) in a controlled field experiment. Density was systematically reduced in three un-fished (and therefore high density) abalone populations in March 2002. After six months a sample from each site was taken and the gonad volume of individuals measured to quantify reproductive investment in response to the density treatment. Gonad development was increased in abalone at reduced density compared with control abalone of the same size. The responses of males and females were different: male abalone were shown to have increased gonad volume regardless of their size, whilst the increase in females was specific to larger individuals. The different responses of males and females may be due to different costs associated with gamete production. In females at one site, gametogenesis appears to have been delayed, but density reduction resulted in increased resources for potential fecundity. This suggests that density effects may be mediated by site characteristics.

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