Fish missing for 14 years rediscovered in Bremer catchment
A FISH not seen in the Bremer River for 14 years is back in record numbers after Queensland's longest fish ladder was built in Ipswich.
The 90m-long fish ladder at Berry's Weir, Yamanto was finished in late 2016.
The weir is at the bottom of the freshwater/tidal section, just before the river becomes a tidal estuary.
At a monitoring session earlier this year, more than 1000 juvenile freshwater mullet were caught and released.
Fisheries biologist Matt Moore of Catchment Solutions, which built the fish ladder, said the results told a compelling story.
"Fourteen years of fish surveys in the Bremer catchment have not detected freshwater mullet, so to catch more than 1000 in a week is an incredible result," he said.
"Over the years, man-made barriers to fish migration have reduced populations of freshwater mullet and many other native species.
"The fact that we are finding freshwater mullet now means the Bremer's 90m long, rock-ramp fish ladder is really starting to show results.
"It is helping our native fish move easily upstream to complete their life cycle."
Berry's Weir was built in the 1960s to impound water for power generation and formed a barrier to fish migration.
The fishway provides a series of steps and pools in a natural rock formation that allow fish to easily ascend over the barrier, in this case the weir, by swimming, stopping for a rest and swimming again.
Across two monitoring days held since the fish ladder was finished, more than 16,000 fish were captured.
Of 15 different species captured, only one was not native. The median size of fish passing through the ladder was 34mm.
"This highlights the use of the fish ladder by juvenile fish, which are generally weaker swimmers than the adults," Mr Moore said.
"To get these kinds of numbers is testament to the success of the fishway. Berry's Weir has historically been a huge obstacle to our native fish."
Adult Australian bass were also found upstream of the weir.
Australian bass are economically and socially important species for recreational anglers and need to move from fresh water to salt water to breed.
Another important species, Mary River cod, was also released into the river as part of a stocking project.
"We are seeing more of our native fish breed and move upstream from Moreton Bay to the freshwater reaches of the Bremer," Mr Moore said.