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.

It has become apparent to commercial divers within the NSW abalone fishery that previously productive areas of reef are now supporting high densities of sea urchins, and correspondingly low densities of abalone. This change has contributed, together with pressure from the commercial and recreational fishery, illegal poaching, disease and pollution, to a decline in the sustainable yield from the population. The current development of the sea urchin fishery in NSW provides the opportunity to re-establish populations of abalone on once productive areas of reef over a large spatial scale. Natural recolonisation of areas of reef will be limited because of the restricted dispersal of larvae from their parents.

A variety of techniques are already being used to help re-establish populations of abalone on depleted areas of reef in NSW. These include the clearance of sea urchins to allow natural recovery, together with the transplantation of broodstock to help increase the speed of recovery. All these techniques are very labour-intensive. The deployment of seed produced from wild abalone provides a significantly more powerful technique to rapidly enhance populations of abalone on depleted reefs over a large-scale. Protocols for the conditioning, spawning and rearing of blacklip abalone are already well established and provide the framework for the year-round production of seed. Techniques for the large-scale deployment of seed have been developed in other states, but recent advancements in our knowledge of settlement substrates suggest further improvements can be made. Similarly, deployment techniques will need to be adapted for the unique conditions on reefs in NSW, and particularly the presence of the sea urchin, Centrostephanus.

With the development of techniques to allow the successful, large-scale release of abalone seed to coastal reefs in NSW, there are likely to be significant benefits to the associated fisheries. In particular, the potential exists for increases in the sustainable yield of the fishery of up to several hundred tonnes per year, or several million dollars.