The impact and implication of Perkinsus olseni on Australian abalone fisheries
University of Adelaide
Perkinus olseni is a protozoan parasite that has negative effects on three commercially harvested abalone species in Australia – blacklip, greenlip and Roe’s. Disease manifestation ranges from high mortality (e.g. New South Wales; Liggins and Upston 2010) to chronic clinical infection (Gudkovs 2016). Chronically infected animals often exhibit extensive macroscopic lesions rendering the product unsaleable. Outbreaks in the 1980s in the South Australian (SA) Central Zone (SACZ) fishery removed 15 t of greenlip catch, with partial recovery of the fishery taking 30+ years. Avoidance of fishing areas in the SA Western Zone (SA WZ) abalone fishery with high prevalence of Perkinsus-related lesions has displaced ~10% (11t.yr-1) of blacklip catch to alternative fishing grounds, exacerbated quota reductions and likely cost the fishery in excess of $10 million over the past ten years. The impact of Perkinsus on abalone fisheries has not been fully quantified and the factors driving prevalence and disease expression are unknown. This information is fundamental for the effective management of this disease, and in particular the prevention of its spread and proliferation. Understanding the impacts of Perkinsus on abalone fisheries and developing strategies for mitigating impacts are the highest priority research need of the SAWZ. These aims are also relevant to the Abalone Council Australia strategic plan and supported by the SACZ and SA Southern Zone abalone fisheries because of the threat this disease poses to both fisheries. This project will consolidate current knowledge on Perkinsus, describe the impact and drivers of the disease in Australia, and determine whether shucking at sea is a high risk. This information is necessary to mitigate the spread and impact of the disease where abalone are currently shucked at sea. If shucking at sea is a high risk we will evaluate alternative ways in which harvesting can occur without further disease spread.
1. Assessment of the economic impact of Perkinsus olseni on blacklip and greenlip abalone fisheries
2. Identify environmental factors influencing the expression of clinical perkinsosis
3. Preliminary evaluation of the fate of viscera discarded at sea
4. Evaluate whether Perkinsus zoosporangia can be detected in faecal pellets following ingestion by fish or other viscera consumers (laboratory trials)
5. If objective 4 indicates zoosporangia detection in fish faeces, hold a workshop to evaluate ways in which harvesting can occur without further disease spread.