When Jason Murdoch survived two heart attacks in three days at the age of 42 he decided “life was too short” and it was time to pursue a passion with purpose.
The first time he tried pest fish-busting he was hooked.
“In the space of an hour, I caught seven fish and I just thought, ‘how good is this?'” Mr Murdoch said.
“I had an absolute ball and have been passionate about it ever since.”
In a man-made lake in suburban south-east Queensland, Mr Murdoch discovered an environmental battleground.
Native fish are being outcompeted by one of the world’s most invasive fish, an aggressive species called Mozambique tilapia.
Their nests are clearly visible as white round patches, stripped of aquatic plants.
“You catch them on worms. You catch them on lures. They’re predatory and they will attack to defend their nests. They will eat other smaller fish,” Mr Murdoch said.
“And I thought, ‘well, why not combine my love of fishing with doing something good for the environment and trying to remove as many of these pests as I can’.”
The environmentally conscious anglers target carp and Mozambique tilapia, sharing pictures and video of their catches and maps of where to find them.
Described as the cane toads of our waterways, tilapia are considered one of the greatest threats to Australia’s aquatic ecosystem.
The noxious species came to Australia in the 1970s as ornamental aquarium fish.
They have spread across the eastern seaboard from Victoria to far north Queensland, and in Western Australian waterways north of Geraldton.
The Northern Territory and South Australia are on alert.
Tilapia thrive in warmer waters but can cope with conditions between 8 to 42 degrees Celsius.
They can survive in salty and oxygen-starved waters, where they invade lakes, ponds, reservoirs, rivers, creeks, drains, swamps and tidal creeks.
“Making sure that it doesn’t get into places such as the Murray Darling Basin is going to be quite critical,” Invasive Species Council conservation director James Trezise said.
“Once it gets into the Murray Darling Basin, we’ll find it spread through southern portions of Queensland right through to South Australia quite rapidly.
“We are at a point with tilapia, where we can take concerted action to stop its spread across Australia’s waterways.
“But that means coordinated action from all levels of government; making sure that we have robust threat abatement plans for invasive fish species.
“We don’t have those for tilapia at the moment.”
As president of the Queensland freshwater fishing and stocking association, Charlie Ladd is eager to educate anglers and has a permit to show them what tilapia look like, in a mobile aquarium.
Tilapia is a popular aquaculture species overseas, but it is illegal to keep the fish in Australia or use them as bait.
“A lot of people now in our community come from countries where tilapia is their primary food for protein,” Mr Ladd said.
“But here there is a strict law, that if you do catch a tilapia or a carp, you must kill the fish humanely and dispose of it.
“You cannot use any part of the fish. You can’t take a fillet off it and throw the frame away and take the fillet home. You have to dispose of the fish fully in a bin or bury it.”
That is because Mozambique tilapia are mouth-brooders.
Females gather the eggs from the males’ nests and carry them in their mouths until well after they hatch.
Both eggs and baby fish can survive long after their mother dies.
“If we don’t dispose of the fish properly, there’s the chance of a young or eggs and getting back into the water,” Mr Ladd said.
“But also, if you allow people to take them home it then puts a value on the fish, where people then will be encouraged to spread them around.”
Mr Ladd said pest fishing competitions, backed up by native fish restocking were an effective way to make a difference.
It works by removing big breeding fish and encouraging native fish to eat their young.
Gold Coast City councillor Hermann Vorster and the Gold Coast Fishing Fanatics club host an annual pest fishing competition, removing as much as a tonne of tilapia and carp in one day.
“We get hundreds of anglers that are on their kayaks and from the shores pulling these fish out. It is an enormous amount of biomass,” Mr Vorster said.
Samantha Beckmann wants authorities to go further and reconsider bans on fishing in some freshwater areas where feral fish populations are.
The fishing instructor, and owner of 2 Bent Rods, runs pest fishing competitions in conjunction with local councils.
“It just seems like they [tilapia] are being protected to a point,” Ms Beckmann.
“They’re in nearly every waterway. They can be in a drain by the side of the road.”
She recommended education, fishing competitions or fishing days, electro-fishing and restocking with native species.
“There needs to be more than one eradication event a year at the locations, two at least, especially if we can’t get the water body opened up for fishing.”