ANGFA Queensland

Original story at ABC News

The critically endangered western trout minnow has been bred in captivity for the first time, in a program that is hoped will help shore up the population.

The western trout minnow was the first freshwater fish species in Australia to be listed as critically endangered. Photo: Department of Fisheries WA

The western trout minnow is so rare it is only found in three small rivers in WA’s Great Southern region.

It was the first freshwater fish species in Australia to be listed as critically endangered.

Researchers from the University of Western Australia and the Department of Fisheries have managed to breed the fish in a laboratory, and hope to restock the rivers in a couple of years.

Principal research scientist Dr Craig Lawrence said there is also a team examining the reasons why the fish are becoming extinct.

“They are specifically looking at the reasons why several rare species in WA have got very low numbers in the wild,” he said.

“Once those factors are identified, we will put together a strategy to address them and it’s only then that we would look at restocking.”

Dr Craig Lawrence has bred the rare minnow in captivity for the first time. Photo: ABC News/Anna Vidot

In 2006 it was estimated that between 2,000 and 5,000 minnows remained in the wild.

Dr Lawrence said researchers had to break new ground in figuring out how to breed the fish.

“We had to work out how to keep them, feed them, breed them, incubate the eggs, raise the embryos, hatch the larva out, and rear them up to fry,” he said.

“They need specific cues to breed. They need the right flow rate, the right temperature, the right barometric pressure.”

He said weirs and dams on water bodies changed the way the rivers flow, which affected the fish’s breeding in the wild.

In one case, researchers built a “fish ladder” to help the animals get around the barriers, and this may need to be installed in other areas too, Dr Lawrence said.

Western trout minnow embryos. Photo: Department of Fisheries WA

The fish’s size was also a factor in breeding it in captivity, he said.

“When we’re talking about these fish, we’re scaling everything down to 1:1000 of what we would usually use,” he said.

“The accuracy of the injections and anaesthesia we use have to be very rigorous and there’s very little room for error.

“No-one else has used these techniques before for a fish of this size.”

The research has been carried out over five years, but the fish only breed four weeks out of the year, Dr Lawrence said.