Overview
The Maugean Skate (Zearaja maugeana) is a unique Australian species found in two estuaries in southwestern Tasmania: Macquarie Harbour and Bathurst Harbour. While there is some uncertainty about their numbers in Bathurst Harbour, recent evidence suggests that if they are there, their numbers are quite small.
It was classified as Endangered under the Environment Protection and Biodiversity Conservation Act in 2004 due to its limited habitat and ongoing habitat deterioration.
New research from the Institute of Marine and Antarctic Studies at the University of Tasmania, funded by FRDC and the National Environment Science Program, has shown that the Maugean Skate is at a high risk of extinction. The main threat to these Skates is poor water quality, especially reduced oxygen levels in Macquarie Harbour, and gillnet fishing. This vast harbour receives substantial freshwater from multiple rivers, resulting in a brownish tint on the surface due to tannins. This reduced light penetration limits the growth of aquatic plants. Macquarie Harbour features distinct layers of water with varying characteristics, including temperature and salinity. The lower most layer closely resembles a marine environment. The primary natural method of replenishing oxygen in its deeper sections is through the inflow of ocean water.
Historically, the Harbour has also been impacted by mining operations upstream, recreational gillnetting and changes in river flows due to hydroelectric dam operations.
Research from the Institute of Marine and Antarctic Studies also shows that the Maugean Skate population has been declining which corresponds to water quality issues, with a major mortality event in 2019 likely linked to extreme weather. Since then, finding young Skates in monitoring surveys has significantly decreased, indicating recruitment issues in the population.
It is important to note that the Maugean Skate is a small species related to other Skates in New Zealand (Z. nasutus) and Chile (Z. chilensis). These related species live on continental slopes, and the ancestors of the Maugean Skate likely inhabited the continental slope of Gondwana millions of years ago before landmasses separated. The reasons for their isolation to just two estuaries are not fully understood but could be related to past climate change events (such as an ice age).
Research management
FRDC in partnership with the Institute for Marine and Antarctic Studies (IMAS) have funded two key projects that have informed the vulnerability assessment for Maugean Skate:
- 2013-008: Movement, habitat utilisation and population status of the endangered Maugean skate and implications for fishing and aquaculture operations in Macquarie Harbour
- 2016-068: Vulnerability of the endangered Maugean Skate population to degraded environmental conditions in Macquarie Harbour
As part of a project 2016-067: Understanding oxygen dynamics and the importance for benthic recovery in Macquarie Harbour, FRDC developed a hydrodynamic model and monitoring platform to inform users of the Macquarie Harbour environment and the regulators.
To ensure the Maugean Skate is properly conserved, Department of Climate Change, Energy, Environment and Water (DCCEEW) formed a Maugean Skate Recovery Team.
The Recovery Team includes representatives from government bodies at various levels, Hydro Tasmania, the aquaculture industry, local communities, research organisations, natural resource managers, and environmental non-government organisations. The Tasmanian Aboriginal community, Copper Mines of Tasmania, and the West Coast Recreation Association have been invited to join group in this important effort.
This team plays a crucial role in planning and carrying out conservation efforts as well as overseas the Federal and Tasmanian Governments partnership to recover Maugean skate in Macquarie Harbour.
Key resources
-
Department of Climate Change, Energy, Environment and Water (DCCEEW)
-
University of Tasmania Institute for Marine and Antarctic Studies (IMAS)
- Listening To The Harbour - describing the oxygen and water quality of the Macquarie Harbour water system
Related projects
|
Project Number |
Title |
Status |
|
Assessing the impacts of gillnetting in Tasmania: implications for by-catch and biodiversity |
Completed |
|
|
Atlantic Salmon Aquaculture Subprogram: characterising benthic pelagic interactions in Macquarie Harbour - organic matter processing in sediments and the importance for nutrient dynamics |
Completed |
|
|
Movement, habitat utilisation and population status of the Endangered Maugean skate |
Completed |
|
|
Managing ecosystem interactions across differing environments: building flexibility and risk assurance into environmental management strategies |
Current |
|
|
Understanding oxygen dynamics and the importance for benthic recovery in Macquarie Harbour |
Completed |
|
|
Vulnerability of the endangered Maugean skate population to degraded environmental conditions in Macquarie Harbour |
Completed |
