Scientists are celebrating a breakthrough in breeding efforts for an imperilled ancient fish, as salmon farming continues to degrade its only natural home.
In a world first, one baby Maugean skate has successfully hatched from a captive-laid egg.
And it’s a girl!
Curiously, the only male in captivity is not the daddy.
The baby arrived on July 10 after a small number of adults were taken from Macquarie Harbour in December.
The species dates back 60 million years and the remote Tasmanian harbour is its only home.
Water quality problems, including from salmon farming, have pushed it perilously close to extinction.
One of the females scooped up in 2023 by scientists from the University of Tasmania’s Institute for Marine and Antarctic Studies has turned out to be an excellent layer.
She has been producing two eggs at a time, every four days or so, ever since and she’s the mother of the new bub.
“We also have a captive male, but interestingly it is not the father,” says IMAS researcher Dr David Moreno.
“Instead, the female is fertilising her eggs with sperm she’s stored from previously mating in Macquarie Harbour, so this sperm could come from several males.
“We know this is the case, because we were keen not to disturb the female while she was laying, so we kept the captive male in a separate tank until about two weeks ago.”
Given the female’s prolific laying, scientists have now put the pair together and they’re showing signs of courtship.
With any luck, the new baby might have a half-sibling sometime soon.
As part of the government-funded program, the IMAS team also brought 50 wild-laid eggs into captivity last year, with more than half of those producing healthy hatchlings.
But captive egg laying is another way to rapidly increase lab-based populations.
“We’ve been trialling captive holding and rearing methods for two years with other skate species,” says Professor Jayson Semmens, who leads the breeding program.
“So successfully producing our first hatchling from a captive-laid egg for this very unique skate is really something to celebrate. It’s a significant step towards conserving the species.”
The happy event offsets bitter disappointment about the deaths of two other adults taken from the wild.
It’s believed fewer than 1000 critically endangered skates are left in Macquarie Harbour.
Federal Environment Minister Tanya Plibersek is reviewing aquaculture approvals for that location.
Before last summer, the federal government’s Threatened Species Scientific Committee called for urgent action to improve water quality problems in the harbour.
It said the fastest and simplest way to resolve those issues was to significantly slash the amount of fish being farmed there.
Salmon Tasmania, which represents the state’s large salmon producers, said there were many factors affecting water quality, including the production of hydro-electricity.
It has instead embarked on a trial to boost the skate’s survival prospects by artificially oxygenating the harbour’s waters.
