New plan to save one of the world’s most threatened rays from extinction: the Maugean Skate will be extinct in a decade unless we act now

PRESS RELEASE |  October 10, 2023

The Maugean Skate, one of the world’s most threatened fish, has less than a decade before extinction unless authorities act soon. ​

The entire population of Maugean Skates lives in Macquarie Harbor on the west coast of Tasmania in Australia, an area of less than 300 square kilometers. Macquarie Harbor’s environment faces many threats, including salmon aquaculture and hydropower that affect oxygen levels in the water, pollution from mining wastes, and fishing. A new conservation strategy report released by Australia’s Federal Minister for the Environment outlines key conservation actions that the Australian and Tasmanian governments should take to prevent the extinction of the Maugean Skate. The minister also announced A$2.1 million in funding to establish a captive breeding program for the species.
 
One of the biggest threats facing the Maugean Skate is aquaculture, or fish farming. This has existed in Macquarie Harbor for decades, but rapidly expanded in 2009. Fish food and waste from fish farms cause low oxygen zones in the skate’s preferred habitat, the deepest parts of the harbor. Skates seek out more oxygen-rich shallow water, where they face new threats, including high temperatures, predators, and fishing gear. But if they get too shallow, they also encounter lower salinity water that is energetically costly for them to deal with on a physiological level. The skates are getting squeezed from both sides. Additionally, during certain types of storms, low oxygen water from the deep is spread throughout the water column, and this is known to kill skates.
 
Hydropower operations in the rivers flowing into the harbor add to the low oxygen conditions by restricting the flow of oxygen rich water into the harbor. Combined with pollution from nearby mines, fishing,  and the environmental impacts of climate change, the Maugean Skate’s only remaining habitat is in serious trouble.
 
Key conservation actions recommended by the new report include reducing the number of salmon fish farms to increase oxygen levels in the water, the use of mechanical devices to artificially oxygenate the water, and modifying hydroelectric dam flows. The report also recommends initiating a captive breeding program, remediation of mining pollution, and a variety of research priorities.
 
The Maugean Skate is listed under Tasmania’s Threatened Species Protection Act and Australia’s Environment Protection and Biodiversity Conservation Act, and is one of 110 that has been prioritized under Australia’s Threatened Species Strategy Action Plan.
  
“The Maugean Skate is a very unique species, being the only skate that permanently lives within estuaries. Living in this environment has exposed it to a variety of threats that if not urgently dealt with could be extinct within a decade.” Dr Colin Simpfendorfer, James Cook University, Australia
 
“The decline of the Maugean Skate has continued despite early warnings and a clear understanding of the cause and the solutions. The science is clear and there needs to be an immediate improvement in water quality in Macquarie Harbor for this species to stand a chance of survival. It is encouraging that there is political commitment to make a change but the urgency is real", added Dr Rima Jabado, Chair of the IUCN Species Survival Commission Shark Specialist Group.