Invader Fish Encroaching On Barramundi

May 12, 2008

Release from: Sydney Morning Herald (Australia)

Prized barramundi stock in the Northern Territory could soon be under threat from an aggressive, fast-breeding invasive fish species, authorities warn.

Mozambique tilapia (Oreochromis mossambicus) were first introduced into Australia three decades ago as an aquarium fish.

Since then, they have been out-breeding and out-eating native fish throughout Queensland and Western Australia.

Their spread through the waterways of northern Australia is fast encroaching on the NT, with tilapia recently spotted in a Queensland river system which drains into the Gulf of Carpentaria.

The sightings have prompted the NT Department of Primary Industry, Fisheries and Mines (DPIFM) to issue a public call for action.

"Territorians are being asked to be on the lookout for tilapia, especially in the Gulf region, and report any suspected sightings," said Aquatic Pest Management coordinator Helen Cribb.

Ms Cribb said tilapia was a highly aggressive species, driving native species away from their natural habitat and reducing native fish populations.

This includes the commercially and recreationally important barramundi.

Tilapia also have the ability to adapt to different environments and breed rapidly.

"Tilapia are capable of having severe impacts on native fish populations, including territory icon species such as barramundi," Ms Cribb said.

"Top End freshwater ecosystems are an important part of the territory's biodiversity and need our help to protect them from pest species."

In addition to affecting recreational fishing, tilapia could also threaten the Top End's multi-million dollar prawn farms and other commercial fisheries.

Ms Cribb urged territorians who believe they have found tilapia or other pest fish to photograph the specimen and record details such as the location, date and time the fish was found.

She said the importation or possession of tilapia - which has been declared a noxious species in the Northern Territory - was illegal and subject to a fine of up to $20,000.