Skate extinction now more likely – salmon farming a “catastrophic risk”
Australia's Threatened Species Scientific Committee has recommended in a very detailed report that salmon farming in Macquarie Harbour be drastically scaled back or even removed entirely to protect the dwindling Maugean skate population (The Mercury, 16 August 2024, paywalled).
The last known population of the Maugean skate is at Macquarie Harbour, where Environment Minister Plibersek is reviewing the future of salmon farming licences amid concerns that aquaculture and other factors are contributing to degraded water quality and reduced levels of dissolved oxygen.
It is now estimated that there are only between 40-120 adult skates remaining in the harbour.
The committee described the risk posed by salmon farming to the future survival of the skate as "catastrophic" and recommended that action be taken to "eliminate or significantly reduce the impacts of salmonid aquaculture on dissolved oxygen concentrations".
The TSSC also noted other factors contributing to the skate's decline, including the impact of hydroelectric damming on river flows into the harbour, saying it could influence oxygen conditions in the bottom waters.
A population viability analysis conducted last year found that the Maugean skate faced a best-case scenario of 89 per cent population decline by 2041 and a worst-case scenario of a decline greater than 99 per cent "assuming no mitigation of … threats". The analysis concluded that the skate had an extinction probability of greater than 25 per cent by 2041.
The public consultation process around the conservation listing will be open until 26 September. Read the report and make your submission here.