Population structure and growth of polydorid polychaetes that infest cultured abalone Haliotis midae

  • CA Simon Department of Zoology and Entomology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa; current address: Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
  • AJ Booth Department of Ichthyology and Fisheries Science, Rhodes University, PO Box 94, Grahamstown 6140, South Africa


Polydorid polychaetes can infest cultured abalone thereby reducing productivity. In order to effectively control these pests, their reproductive biology must be understood. The population dynamics and reproduction of polydorids infesting abalone Haliotis midae from two farms in South Africa is described using a length-based, age-structured model. Shells were infested mainly by introduced Boccardia proboscidea. Polydora hoplura and Dipolydora capensis were also present but in numbers too few to identify factors influencing infestation. At both farms, B. proboscidea lived for a minimum of 12 months. Growth rate, size at maturity, maximum size, infestation intensity, recruitment, percentage of the population brooding and mortality appear to be affected by abalone feeding regime and water temperature, and these factors need to be considered in controlling infestation. Brooders and recruits were present throughout the year, but increased significantly during mid- to late winter/early spring when water temperature and day length increased. Treatment measures should therefore be implemented throughout the year but with increased effort when water temperature increases.

Keywords: age- and size-at-maturity, growth, mortality, recruitment, temperature

African Journal of Marine Science 2007, 29(3): 499–509

Journal Identifiers

eISSN: 1814-2338
print ISSN: 1814-232X