BANDED GRUNTER FISHINGTHREAT
By TOBY WALKER
A CALL has gone out to Clarence Valley anglers to help reduce the spread of a predatory fish that researchers believe could devastate the local prawn industry.
The banded grunter was first sighted in the Clarence River in 1999 and has since thrived due to a lack of any natural competitor in the river system.
A perch-like fish with a distinctive pattern of five vertical black stripes on a silver-to-bronze background, the banded grunter is an aggressive predator that can prey on the eggs and juveniles of native fish.
Researchers have so far located the fish in the Clarence River between Grafton and The Gorge but some believe it might have made it into the Orara River.
It is believed the fish was introduced into NSW waters accidentally through contaminated shipments of fish from Queensland hatcheries.
Commonly growing to about 8cm to 12cm, the banded grunter has little value as a sport or table fish.
Gavin Butler, a researcher at Grafton's Aquaculture Centre, has conducted studies on what has been dubbed the 'Clarence carp' to try to understand its breeding cycles.
"Anytime you release something into the water in an open system like the Clarence River, there's no real way of containing it," he said.
"The other major study that has been done on the banded grunter in the Northern Territory found their average size to be about 70mm but our average in the Clarence has been 140mm.
"What that indicates is that there's a lot of large adults in the river which means greater reproduction potential and an exploding population, basically."
Researchers hope government funding will be forthcoming to assist in further research which could help develop methods of keeping the banded grunters' numbers down but until then they are relying on anglers to come to the rescue.
"We're trying to get the support of the professional fishermen because obviously one of the worries is that the fish will eat small prawns," he said.
"If we end up with large numbers in the future then its probably going to affect the river's prawn stocks.
"From what we've seen, the people that generally are the most successful at catching them, without wanting to obviously, are the anglers looking for garfish.
"So if you use gar rigs, which is light line, floats, little hooks and a small amount of bait then they seem to be pretty easy to catch.
"They're really aggressive at the bait so fishermen hate them because once you start catching them it brings all the others around because they're a school-type fish so you end up with 20 or 30 sitting around the bottom of your boat eating your bait."
Sightings of banded grunters and other pest species can be reported on a government hotline, 02 4916 3877 or by e-mail on email@example.com.