The Queensland government will study fish ecosystems after back-to-back La Nina events

Hundreds of harmful fish have been caught in rivers in southern Queensland, with repeated rains muddying the waters and causing an explosion in fish numbers.

Although the flooding earlier in the year was good for local fish populations, it also led to an increase in carp.

That prompted recreational anglers and the state government to restore Dogwood Creek, a key spawning ground for the native species about 400 kilometers west of Brisbane, and begin collecting data to monitor fish numbers.

According to Peter Delaforce, angling enthusiast and president of the Miles District Angling Club, the problem has gotten worse over the years.

“It’s a big difference,” he said.

“On a weekend where you’re going to get 10 to 15 local fish, you might get 100 to 200 carp.”

Native species that call south-west Queensland home include Murray cod, eel tail fish and golden perch, more commonly known as yellowbelly.

Mr Delaforce said Dogwood Creek fed into larger rivers and the Murray Darling Basin and was most affected by the severe weather.

“There are several places in the Karingal Reserve near Miles that have four to five meters of wash. [erosion],” he said.

“The rain also washed away a lot of water from the local soil, which made the water muddy and cloudy.”

100 carp were caught in one day compared to eight yellowbelly and five jewfish.(Courtesy: Miles District Fishing and Recreation Club)

Fishermen struggle with power

Although the ground is wet, members of the Miles District Fishing and Recreation Club have taken it upon themselves to restore parts of Dogwood Creek.

a man holding a pot of young plants
More than 1,500 trees have been planted along Dogwood Creek to protect the soil from erosion.(Courtesy: Miles District Fishing and Recreation Club)

A 20-strong team of local residents and OzFish volunteers from Ballina, Moree, Brisbane and the Sunshine Coast planted more than 1500 native trees along the banks of the creek.

Juvenile plants were exclusively native species to the region, such as bottlebrushes and other callistemons.

“They are planted as close to water as possible,” Mr Delaforce said.

As the trees mature, they will overhang the creek to help provide shade and food.

“All the insects on the trees will fall into the stream and become food for the fish.

“Everything has been planted up to the level of the last major flood and we will keep those plants for the next 12 months.”

In addition to preventing soil erosion, the club held regular fishing competitions to add to the pest fish data.

“When we run a carp competition, we photograph, weigh and weigh every carp caught,” Mr Delaforce said.

“We’re aggregating how many native fish are harmful fish in those waterways.”

The data is then provided to the Queensland Department of Agriculture and Fisheries.

young boy with carp lining on the sand
The carp is measured and photographed, then disposed of as biohazardous waste. (Courtesy: Miles District Fishing and Recreation Club)

Entering the depths of Dogwood

The Department of Agriculture and Fisheries has begun a study of Dogwood Creek to predict where money will be spent on its rehabilitation.

Chief scientist Andrew Norris said it was a deep process.

“The first step is to get some initial inquiries to see what we’re up to,” Mr Norris said.

“It uses electro-fishing boats that stun the fish. They rise to the top, we count them, measure them, then put them back.

“We will also put some nets out overnight to catch smaller native fish that normally go undetected.”

reflections in the lake at sunset
Dogwood Creek feeds into the Murray Darling Basin and is a major local fish breeding area. (Supply: Queensland Country Fishing)

Mr Norris said he expected to find large numbers of native freshwater fish, which were abundant throughout the Murray Darling Basin catchment but declining in other areas.

“The recent rain events have actually been fantastic for local fish,” he said.

“The problem is that they don’t happen all the time. That’s why we’re trying to implement longer-term strategies.”

The Dogwood Creek study was similar to a 2008 study of jewfish in nearby Dalby.

Mr Norris said all the projects were led by local fishing enthusiasts.

“Community groups are the unsung heroes in fish rehabilitation,” he said.

“There’s only a certain amount of money, and volunteers put a lot of effort into it.”

Surveys and meetings with local landowners will continue this year and into 2023.

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