Do you ever look at photos in old fishing magazines and books and think you were born too late, or wonder what the fishing would have been like 70 years ago?
Many of us have never experienced fishing in the inland waterways of the Murray-Darling Basin without introduced fish such as carp, which really took hold in the 1960s and 70s. You could say we have been left a legacy of the past that we would rather not have inherited. For the first time in Australian history, effective carp control is looking promising in the Murray-Darling Basin, thanks to the carp herpes virus.
Despite carp, it has been a cracker of a season in the northern inland. This magazine has been chock-a-block full of big cod and golden perch from rivers and impoundments, almost reminiscent of those old fishing magazine photos.
In the coastal rivers and impoundments across South East Queensland and Northern NSW, it’s also apparent another introduced fish, tilapia, are becoming a more common by-catch for anglers chasing natives.
Tilapia are extremely efficient breeders, and are highly tolerant of harsh conditions and poor water quality. In approximately 40 years, tilapia have spread throughout many coastal catchments in Queensland, from Cairns in the north all the way to the NSW border and beyond. In some places, they are found within 3km of the Murray-Darling Basin.
The most widespread species of tilapia in Eastern Australia is Oreochromis mossambiccus, an aggressive fish that grows to 40cm and varies in colour from dark olive to silver-grey, depending on their age and environment. Breeding males often have red tips on their fins. They are generally deep-bodied fish with a thin profile and one continuous and pointed dorsal (top) fin and pointed anal fin.
Females protect their eggs and young fry in their mouths. This technique, known as ‘mouth brooding,’ ensures high rates of survival. Even if the mother is not living, any eggs in the mouth have the potential to survive if released into a waterway.
Tilapia impact our native fish through predation, habitat destruction, and competition for habitat and food. Like all introduced fish, tilapia also pose a risk of spreading diseases and parasites. Once they become established in a flowing waterway or large impoundment it is extremely difficult, if not impossible to eradicate them.
Tilapia are a Class 1 Noxious fish in NSW. This means that it is illegal to posses, sell or import live tilapia.
In inland waters of NSW, the use of live fin fish including live carp or other pest species (like tilapia) as bait is prohibited. Also prohibited is the use of parts of non-native fish as bait whether alive or dead, other than dead carp.
NSW DPI recommends that any person that comes into possession of tilapia humanely kill the fish, photograph and freeze the fish whole (to allow later confirmation of identification). If freezing the fish is not possible, dispose of it in a bin going to landfill or bury it away from the water.
Despite these regulations, tilapia infestations are most commonly caused by people moving them between waterways. With more and more people travelling long distances to fish, there is a very real risk of a tilapia incursion in the Murray-Darling Basin.
While it looks like we will have to put up with tilapia in the coastal catchments for the time being, we can prevent them from getting into the Murray-Darling Basin. The recreational fishing community has a role to play in stopping the spread of tilapia.
If there is an incursion in the Murray-Darling Basin, any chance of effective control is reliant on early detection and rapid reporting. If you catch a tilapia, observe any nests or see people moving them, report it!
Unless we want our kids to grow up wondering what fishing for Murray cod and golden perch used to be like before the tilapia invasion, we all have a duty of care to do the right thing and not move tilapia between waterways.
With carp management looking more promising than it ever has, it would be a tragedy for native fish of the Murray-Darling Basin and recreational fishing if the carp gap was filled by tilapia.
To help stop the spread of tilapia:
|•||Don’t throw caught tilapia back into a waterway—kill the fish humanely, take a photo and either bury them or put them in a bin and report it as soon as possible.|
|•||Don’t use tilapia as bait (dead or alive).|
|•||Don’t stock dams or ponds with tilapia—stock native local fish instead.|
To report tilapia in QLD call 13 25 23 or visit www.daf.qld.gov.au. The Keep Tilapia Out project is supported through funds from the Murray-Darling Basin Authority. – Charlie CarruthersReads: 299