Tasmanian scientists striving to save an ancient fish from extinction are feeling the loss of two adults that were taken from the wild for a crucial breeding program.
But while the deaths are difficult to accept they are part of the journey for experts who must quickly figure out how to keep the Maugean skate in captivity.
The species dates back 60 million years but salmon farming and other pressures have affected oxygen levels in Tasmania's Macquarie Harbour and there are now fewer than 1000 skates left.
With no other populations in existence, a captive breeding program has been ordered to ensure there's an insurance population if the harbour community dies.
But figuring out how to keep the species alive in an artificial environment is no easy task.
Before four adults were harvested from the harbour in mid-December the longest time a Maugean skate had survived in captivity was about a week.
Professor Jayson Semmens, from the University of Tasmania's Institute for Marine and Antarctic Studies, is leading the captive breeding program and says the fact two adults are still going strong after a month is a big win.
"They are an incredibly specialised species. They live in one place in the world, they are the only species of skate that's wholly estuarine, they only feed on one prey type, and they live in a very unusual environment.
"It's awful and sad and of course we'd prefer it not to happen but we expected mortalities, because this is very new. So we started small for that exact reason."
Amid the sadness at the loss of an adult male and an adult female there is some good news.
The surviving male and female are thriving, and 50 eggs divers also took from the wild are starting to hatch.
There are two babies so far. Not all of the 50 eggs will be viable, but it's hoped about 40 per cent will be.
An ultrasound has shown the surviving adult female is also pregnant and should begin laying eggs soon.
Prof Semmens says the crucial thing is for scientists to learn from the loss of the two adults, one of which struggled from the start, with the other dying suddenly.
Samples have been taken from their little bodies and sent to a specialist animal health lab in the hope some answers can be found.
In the meantime, there are no plans to harvest any more adults or eggs from the wild, with experts focused on the survivors, the hatchlings, and the eggs, which take about seven months to hatch.
"The important thing is that we learn, and understand, and take those learnings forward and improve as we go. If we do that, then we're doing our job."
Tasmanian Greens Senator Peter Whish-Wilson has praised the team tasked with helping the skate recover but fears it may already be too late, given salmon farming impacts on oxygen levels in Macquarie Harbour.
“We have to do so much better to protect the skate in its only natural home, Macquarie Harbour," he said.
“The federal government’s own updated scientific advice clearly states the key threat to the skate’s survival is poor water quality in the harbour, and that the primary cause of this is Atlantic salmon farming.
"The fastest and simplest way to give the Maugean skate a fighting chance of survival is to remove toxic industrial salmon farming from the skate’s natural environment – it’s that simple."
Salmon Tasmania will soon begin a trial to mechanically oxygenate water in the harbour, as part of efforts to boost the skate's survival prospects.
The trial is happening alongside a review of aquaculture operations, which opponents hope will have the industry exit the harbour for good.
