Murray crayfish populations are set to be reintroduced in South Australia's River Murray for the first time in 40 years.
Aquatic ecologists at Aquasave Nature Glenelg Trust have been granted a permit to release the species in the river in the next couple of weeks.
"Murray crayfish have been declining in distribution and abundance all throughout Australia … but unfortunately in SA the last record was in early 1980s," Aquasave Nature Trust Glenelg senior aquatic ecologist Sylvia Zukowsi said.
"We've been given the permits and now we're hoping at the end of April or beginning of May will be the release time to get them back in the water," she said.
The releases will occur at the end of April in areas of Berri and Loxton.
Some Murray crayfish were saved from blackwater events in New South Wales from the floodwater and stored in SA, which are the ones granted for release in SA's river system.
How the reintroduction will work
Murray crayfish thrive in fast-flowing, well-oxygenated water.
"The water quality is good in South Australia and those regions we're looking to put them in definitely have that good water quality and they've got the fast-flowing sections of river which are perfect and ideal for Murray crayfish," Dr Zukowski said.
"We'd obviously be targeting initially those sections that are well suited to Murray Crayfish."
She said a breeding program will ideally be established where the animals are bred in captivity after initial reintroductions.
"Hopefully in the long term the plan would be to actually start a breeding program which would be amazing and keep doing reintroductions on a yearly basis," she said.
What caused their decline
Overfishing, river regulation, pollution and salinity were all contributing factors to the decline of the Murray crayfish in SA.
"They're not like a fish that can travel downstream and repopulate, they don't move further than 300 or 400 metres."
The species has a long life span of up to 30 years, and doesn't begin breeding until about age 8.
"This is a bit of a thing that's not in their favour because unlike a fish that starts having offspring at one or two or earlier, these guys wait a long time before they're sexually mature," Dr Zukowski said.
When young they can also be cannibalistic in nature making breeding even harder.
