The Maugean skate is still facing extinction in its only home, Macquarie Harbour, because of the low oxygen levels in the harbour’s deeper waters, the Australian Marine Conservation Society said after Tasmania’s Environmental Protection Authority released a report on the harbour’s oxygen levels.
AMCS shark scientist Dr Leonardo Guida said: “In the deeper waters of Macquarie Harbour oxygen levels are still not at the level where the Maugean skate can safely live in its only home. Oxygen levels have improved slowly in the harbour partly because of natural oxygen recharging from sea water entering the harbour over summer.
“It was the upturning of deep, oxygen-depleted waters from storms that wiped out nearly half the Maugean skate population in 2019. Things may literally look good on the surface but, like most things, you need to go a bit deeper to get the full picture.
“The Maugean skate is on the brink of extinction, it does not have enough time to wait for the oxygen levels to slowly recover to the levels they need to live and survive. There are only about 1000 skates left in Macquarie Harbour and its extinction could be in as little as 10 years’ time, possibly earlier if a big storm creates another upturning event.
“Salmon farming has dramatically depleted the oxygen levels in Macquarie Harbour, and removing salmon farming is the fastest way to improve oxygen levels for the skate to survive and recover.
“Salmon stocks in Macquarie Harbour peaked in 2015 at about 20,000 tonnes – the equivalent mass of about 1000 humpback whales. The salmon industry has not reduced biomass far enough in that time, so the federal government needs to act on its own Conservation Advice, which recommended the removal of salmon last summer.
“The Albanese government has made a commitment to zero new extinctions. We’re calling on Environment MInister Tanya Plibersek to see that salmon farming ceases in the harbour to meet this commitment and ensure the skate’s survival.”
