View Full Version : Stocking Snippets. Volume 2. Edition 7.

08-11-2001, 01:27 PM
DPI is developing a project to look at the biology and ecology of tilapia and to investigate control measures. There are two species, the Mozambique mouth brooder and the black mangrove cichlid, which are currently causing concern in Queensland.
These species are well established in some natural watercourses and impoundments in eastern Queensland and parts of Western Australia. Records of their occurrence in the wild go back to the 1970s. #In Queensland, several specimens of the Mozambique mouth brooder were caught in Tingalpa Reservoir, Brisbane in 1977 and the North Pine Dam, Brisbane in 1979.
Populations were identified from urban drains and ornamental ponds in the Townsville area in 1978 and an unsuccessful attempt was made to eradicate this population using poison in 1980. #In the early 1980s, stocks of the Mozambique mouth brooder were found in ornamental ponds in the northern beaches of Cairns where attempts at eradication using poisons also proved to be unsuccessful.
In the late 1980s they were found in an artificial pond on a resort at Port Douglas. #Subsequently, this pond was successfully poisoned using rotenone resulting in the removal of an estimated 13 tonne of fish, almost entirely tilapia. Anecdotal evidence suggests that these numbers built up from 5-10 fish stocked in the ponds about 18 months before.
Recently, a population of tilapia was found in Lake Tinaroo and there are fears that it may spread to the rivers of the Gulf of Carpentaria through the Mareeba-Dimbulah irrigation system. Tilapia were also recently found in Boondooma Dam in the Burnett catchment. Black mangrove cichlids are common in the rivers and creeks around Cairns.

Potential impacts of tilapia include:
- # # #becoming the dominant species through aggressive behaviour
- # # #competing for habitat and food resources
- # # #reducing biodiversity
- # # #disturbing substrate and weed beds through nest building activities.

To assist in managing this exotic fish, the proposed DPI project will aim to find out as much as possible about the biology and behaviour of tilapia in the wild. #This will include:
* breeding behaviour # # # # # # # # #
* spawning season
* movements # # # # # # # # # # # #
* age at first maturity
* population structure # # # # # # # # #
* number of eggs produced
* habitat preferences and # # # # # #
* parasites.
In addition, the project will investigate use of biological control as a means of eradicating or limiting tilapia numbers in certain conditions. #If this research is successful, it may prove to be one of the few available ways of controlling tilapia populations in the wild.

This proposal has received an A rating from QFIRAC (Qld Fishing Industry Research Advisory Committee). This is the first hurdle. It must now progress through two further rounds of applications. If successful, the project will commence in July next year and run for three years. For further information contact John Russell, Northern Fisheries Centre, on 40350100 or russelj@dpi.qld.gov.au

Aquatic Invaders, the new pest fish education module was recently launched by The Minister for Primary Industries. This module is aimed at upper primary and lower secondary school teachers and links in with the new school curriculums. It contains heaps of great activities and aims to be a “one-stop-shop” for teachers. If you would like a copy please contact Rachel Mackenzie on 3239 0727 or mackenrf@dpi.qld.gov.au