A wave of mortality has decimated (i.e. hundreds of tonnes killed) abalone stocks in NSW, and caused significant losses (i.e. >$3 million per year) to stakeholders in the fishery and unknown effects on the coastal environment. This project is a direct outcome of a National Workshop on Perkinsus, attended by government agencies, FRDC and Industry, where the need for urgent research was recognised.
It is unclear if the mortality of abalone is still spreading because of a lack of information from the fronts of mortality. Should the mortality spread further south into increasingly high density stocks of abalone, there will be a rapid escalation of impacts. The lack of information about past and current effects on abalone populations is directly compromising current management of the fishery within the affected area.
There is very little information currently available about what is killing the abalone. Sick and moribund abalone have been found to be infected by the protistian parasite, Perkinsus olseni. Despite that, it is not clear whether Perkinsus is responsible for the mortality, or whether other factors are involved.
There is a strong and urgent need for basic information about the past spread, and current pathogenesis and epidemiology of the mortality of abalone in NSW. Outcomes of the project will directly aid current management of the fishery in the effected area through information on the stock that remains and an understanding of the causes of the mortality. Ultimately, this research may also provide techniques to reduce the effects and spread of mortality that can be incorporated into future management strategies for all abalone fisheries in Australia that could be affected by Perkinsus-related mortality.
Final report
Since the early 1990’s, a significant proportion of blacklip abalone (Haliotis rubra) along approximately 500 km of the NSW coastline between Port Stephens and Jervis Bay have died. Sporadic histological examination of moribund abalone since 1992 and a survey of infection prevalence in abalone using Ray’s test in 2002 confirmed infections of a protistan parasite, Perkinsus sp., in abalone. It has been assumed that the species is P. olseni, but this has not been confirmed (prior to this project). It has been unclear to what extent mortality of abalone has been caused by Perkinsus. Other factors may also have been responsible for the mortalities. Should the Perkinsus-related mortality spread further south into increasingly high density stocks of abalone, there would be a rapid escalation of impacts.
Against this background, there was a need to: document historical evidence about the spread of Perkinsus-related mortality of abalone in NSW; describe the pathogenesis and epizootiology associated with the mortality of abalone and the role of Perkinsus; and to contribute to the development of management strategies to manage populations of abalone that have, or might be affected by Perkinsus-related mortality and evaluate the need for further research.
Based on structured interviews of divers, mass mortalities of abalone occurred during the year (+/- 1 year): 1992 on the Central Coast of NSW, 1993 at Sydney-Wollongong, 1996 at Kiama and 2000 at Port Stephens. A sudden decline in abundance of abalone, unaccompanied by observations of morbidities or mortalities, occurred at Jervis Bay during 2000 – 2002.
Keywords: Perkinsus sp., Perkinsus olseni, perkinsosis, Ray’s test, histology, PCR, pathogenesis, epizootiology
