Media release – Institute for Marine and Antarctic Studies (IMAS), 16 May 2023
Under pressure: scientists call for urgent conservation action to save Maugean skate
The evidence is in and scientists are calling for urgent conservation action, after monitoring revealed that the Maugean skate population has rapidly declined by almost half in Macquarie Harbour, Tasmania – their last remaining habitat and one that is significantly impacted by human activity.
“We’ve monitored the skates since 2012 and found the population declined by almost 47% between 2014 and 2021. It is also concerning that very few juveniles are coming through to keep the population viable,” said researcher Dr David Moreno, who leads the Maugean skate monitoring project at the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS).
The monitoring project was established to track changes in Maugean skate numbers, when IMAS scientists became concerned that the population was under stress.
“We recently found that Macquarie Harbour was the last remaining habitat for Maugean skate and, like other endemic species, this limited range means their conservation is inextricably linked with the health of the system they live in,” Dr Moreno said.
“The downward trend in relative abundance, together with this unique skate’s restricted range and extremely limited genetic diversity in the population, is clear evidence that the population is at risk.”
IMAS researcher Professor Jayson Semmens agreed. “The environmental changes in the harbour have increased the skate’s vulnerability to sudden high-impact events, such as water column turn-over driven by westerly winds, which can happen at any moment and potentially decimate the population,” he said.
“For example, when the stress from a degraded marine habitat was coupled with a storm event in 2019, we found widespread mortalities among the skate we were electronically tracking.
“We are fortunate that IMAS has been collecting data on Maugean skate in Macquarie Harbour since 2012, as the decline in abundance could easily have gone undetected. We don’t know whether, or how significantly, the population had already declined before monitoring began, but what we do know is how quickly this most recent decline has happened.”
Dr Moreno said the evidence provided in the new monitoring report highlights that this program would ideally be continued beyond 2023.
“The reality is that we risk losing an important species which only exists in this harbour. So human activities related to the skate need to be managed, such as recreational fishing, and those that affect the marine environment such as salmonid aquaculture and river flow management for hydro production,” Dr Moreno said.
“While funding for the monitoring project does not currently extend beyond 2023, this study shows the value in being able to track the Maugean skate’s population changes through time and in response to management action. Captive breeding to develop an ‘insurance’ population should also be considered.”
This project was supported with funding from the Tasmanian Government through the IMAS Sustainable Marine Research Collaboration Agreement (SMRCA).
Featured image courtesy Jane Ruckert.
Media release – Environment Tasmania, 16 May 2023
LATEST IMAS REPORT SUGGESTS MAUGEAN SKATE SET TO BECOME THE “THYLACINE OF THE SEA” AND YET NO REDUCTION IN MAC HARBOUR SALMON PENS ORDERED
An interim report published today by the Institute of Marine and Antarctic Studies (IMAS) shows how maugean skate numbers have almost halved between 2014 and 2021. There has also been a decrease in the numbers being caught per effort, and an increase in the average size of females caught which means there are less juveniles either being born or surviving into adulthood.
The situation is so dire that a captive breeding program is being planned. Reduced oxygen levels in Macquarie Harbour are being cited as a major reason for the skate’s demise, and one of the major contributors to low oxygen is the presence of the salmon industry.
“The situation for the maugean skate is really very dire and without drastic action, Tasmania will have the grim record of the second bony fish extinction in the world on its record, after the smooth handfish. Not only would the extinction of the maugean skate be an absolute tragedy for Tasmania, but it would also be an embarrassment to federal environment minister Tania Plibersek who pledged zero extinctions on her watch,” says Rebecca Howarth, Marine Campaigner for Environment Tasmania.
“The presence of the salmon industry has contributed to reduced oxygen levels in Macquarie Harbour pushing the especies to the brink of extinction. This is compounded by warming waters and the only solution is to rest Macquarie Harbour of salmon pens to allow the iconic species to recover.”
“The responses from the Environment Protection Authority (EPA) and the Department of Natural Resources and Environment Tasmania (NRET) do not go nearly far enough. Reducing the feed allowance of salmon farms in Macquarie Harbour by 10% and forming working groups is too little too late. This is not decisive action to ensure the survival of an endangered species. This is yet another example of the Tasmanian government pandering to industry. The solution is to rest Macquarie Harbour entirely to allow the species to recover.”
“We support the application of the Australian Marine Conservation Society (AMCS) and Humane Society International Australia to have the maugean skate upgraded from endangered to critically endangered. We urge Ms Plibersek to intervene to ensure the survival of this iconic and ancient species.”
