The Maugean skate (Zearaja maugeana) is a species of ray only found in the waters of Macquarie Harbour, on Tasmania’s south-west coast.
The skate has previously been recorded in Bathurst Harbour, but the status of the population is uncertain, and recent research by the Institute of Marine and Antarctic Studies (IMAS) considers Macquarie Harbour the last known population of the species anywhere in the world.
Monitoring shows that in recent years there has been a significant decline in the remaining skate population and without intervention, the long-term survival of the species is unlikely.
Current numbers of Maugean skate are thought to be around 1,000.
The Maugean skate is listed as endangered under both Tasmania’s Threatened Species Protection Act 1995 and the Commonwealth's Environment Protection and Biodiversity Conservation Act 1999.
Recent conservation advice appears to indicate that primary threat to the skate is degraded water quality, particularly reduced levels of dissolved oxygen in Macquarie Harbour.
This report from the Department of Climate Change, Energy, the Environment and Water outlines some of the human-driven and natural factors that may contribute to low dissolved oxygen levels in the harbour.
In July 2023, the Australian and Tasmanian governments established the Maugean Skate Recovery Team to develop and coordinate conservation efforts.
The recovery team includes members from federal and state government departments, industry, environmental groups, experts and researchers, and community groups.
Hydro Tasmania has been an active member of the recovery team since its inception.
You can find more information about the National Recovery Team here. And in January 2024, the Department of Natural Resources and the Environment Tasmania published the Conservation Action Plan for the Maugean skate. Hydro Tasmania is delivering its commitments under the plan.
The truth is we don’t know for certain.
Hydro Tasmania operates two power stations upstream of Macquarie Harbour:
We know the water leaving our power stations is healthy and not low in oxygen. Research shows that flows from power stations are not considered a primary cause of low dissolved oxygen in Macquarie Harbour. But they could be part of the solution.
We’re working with the National Maugean Skate Recovery Team, and Commonwealth Scientific and Industrial Research Organisation (CSIRO), to redevelop a comprehensive hydrodynamic model of Macquarie Harbour.
This model will identify any correlation between hydropower operations and dissolved oxygen levels in the harbour. It will help us understand how we might be able to manage water flows from our power stations upstream, to support a healthy environment downstream for the Maugean Skate.
Macquarie Harbour is a complex system and changing flows is not as simple as turning a tap on and off. We need to make sure we’ve got all the information to fully understand what changes, in what conditions, could help the skate without adversely impacting other parts of the ecosystem.
In January 2024, Department of Natural Resources and Environment Tasmania published a Conservation Action Plan for the Maugean Skate. Hydro Tasmania is working with stakeholders to implement the plan.
Hydro Tasmania employs a team of scientists and experts who work to preserve the biodiversity of our waterways.
This includes efforts to protect threatened galaxiids, and rediscover species such as the short-tailed rain crayfish and an aquatic snail species, both thought to be extinct.
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