Rare fish, near extinction, returned to wild

Issued: 20 August 2020

An urgent rescue mission led by the Queensland Government has saved a rare and ancient native fish from potentially becoming the first freshwater species to be lost from Queensland due to climate change.

Principal Scientist from the Department of Environment and Science (DES) Dr Jonathan Marshall said Queensland scientists had successfully established a new population of the fish species, the river blackfish, near Killarney in southern Queensland.

“It’s now only the second population of the threatened species to exist in Queensland,” Dr Marshall said.

“Before last week, river blackfish were known from only one stream in Queensland. Now, they occupy two.

“The cold-water fish species which were widely distributed millions of years ago when the climate was cold and wet, have been under increased pressure from rising temperatures and dry creeks.

“In February, a team of ecologists captured 50 river blackfish from Spring Creek in the upper Condamine River catchment, where the flow of water almost stopped due to extreme heat and drought.

“After being housed in a specialised refrigerated aquaculture facility as an ‘ark’ or insurance population until natural conditions improved, the fish were released back into the wild in nearby Adjinbilly Creek, which is a rocky, spring fed stream with all the characteristics of ideal blackfish habitat, creating a second population.

“River blackfish are an ancient cold-water species that die if the water temperature rises above 28 degrees.

“As the population at Spring Creek was isolated with no chance of recolonising locally, I have no doubt the fish were at serious risk of local extinction if immediate action was not taken.”

Griffith University, James Cook University and Jardini Pty Ltd also participated in the DES rescue mission thanks to emergency funding from the Murray-Darling Basin Authority.

“This is a significant step towards re-establishing the natural range of blackfish and will greatly aid in the ongoing conservation of the species,” Dr Marshall said.

“The Adjinbilly Creek population may also act as an insurance policy for the Spring Creek population in case catastrophic conditions return in the future.

“Water samples will be taken from both creeks in coming months for environmental DNA testing to determine if the establishment of the new colony is successful.

“DNA is constantly being shed from fish and other animals into the environment. If blackfish DNA is detected in the water samples, this will mean the re-introduced blackfish are alive and established.

“It is the first blackfish re-stocking project ever attempted in Queensland, and I congratulate the team involved in this successful project.

“The health and size of the fish improved significantly while they were in captivity and many are now in good breeding condition.”

Owner of Adjinbilly Rainforest Retreat Tony Hoopmann said the reintroduction of blackfish into Adjinbilly Creek is exciting for the local area and supports local conversation efforts.

“For a fish thought to be extinct from this creek for ten years or more, to be given a chance to once again live where it originally came from is very exciting,” Mr Hoopmann said.

“Long ago, the creek was once a refuge for blackfish where they would retreat to when the world was a lot hotter.

“The guests who visit our retreat are fascinated by the crayfish and other animals that survive throughout the Gondwana Rainforest. The blackfish are an amazing example of how these animals have survived over tens of thousands of years.”

Kim Charles, Member of the Githabul people, has also supported the project.

"It's always positive to see environmental care in action," Kim said.

"The proactive scientific approach was most interesting, fresh and sensible. Rare native fish were removed from danger, then reintroduced back to country.

"It's encouraging to know that the species is protected, along with our culture through the ability to share knowledge in a cooperative and mutually respective way."

Videos, photographs and interviews are available from the media centre.