It was two years ago that the recreational fishing group worked with SA Water to release fingerlings into the Happy Valley, South Para, Myponga, Warren, Bundaleer, Aroona and Beetaloo reservoirs as the areas opened to the public for the first time.

This week, the group proudly posted a picture of recreational fisher Jack Schiller at Bundaleer reservoir holding a giant Murray cod that had reached about 10kg, with the group saying the species is likely to begin breeding when it reaches 5kg.

“These fish are starting to staunch up and get towards breeding size, attracting a huge amount of interstate and regional travel interest in South Australia,” the post said.

“The handling and care for these fish has been top level from the freshwater community – keep up the good work and stewardship, and these fish will be 50 pounders in no time.”

RecFish SA executive officer Asher Dezsery was hopeful that numbers of the freshwater fish listed as threatened would soon swell, with the group having kept watch for signs of spawning over the past year.

“We’ve not seen an obvious cohort of young cod, just the larger fish, they have only really just hit breeding size this year, so it could be this year or the year after that they will spawn,” Dezsery said.

Murray cod are protected and must be released if caught in reservoirs all year, with catch-and-release fishing allowed outside of reservoirs between January 1 and January 31.

Dezsery said that it was in the warmer and lighter months generally starting around the Adelaide Show weekend and stretching through to December that the cod were most likely to spawn.

RecFish are now working with SA Water and the South Australian Research and Development Institute to explore whether the state’s reservoirs that have been stocked with the fish have adequate habitat for the Murray cod to breed.

This includes tracking numbers and investigating whether there are suitable structures that could be installed at reservoirs that would not affect the quality of drinking water, but support the fish that like to live among and breed in logs.

Dezsery said RecFish held a fishing clinic at Happy Valley Reservoir in October attended by about 350 people where about a dozen cod were caught and fishers were taught best practice in correctly handling and releasing them.

“Some of them were caught by kids and it was the first fish they had ever caught – their first fish a 30cm to 60cm cod – most people try their whole life to catch fish that big,” he said.

Murray cod successfully growing in reservoirs was considered positive as they could act as an “ark” and re-supply the River Murray with the species if problems were encountered with numbers in the future.

Protecting the cod in the reservoir so they could live 15 to 20 years of age was also important, Dezsery said, allowing them to spawn continually and reach top sizes that historically have been recorded at more than 40kg.

This meant they could also act as a prized drawcard for fishing tourism to South Australia, where recreational fishing is a $1 billion industry attracting about 360,000 people each year.

The reservoirs also have bag limits on other fish that were released as fingerlings in 2021 including silver perch, golden perch, redfin and trout.