Unfortunately for researchers, a recent fish stock monitoring survey occurred simultaneously with rising water levels in Bjelke-Petersen Dam.
The survey, undertaken by Fisheries Queensland extension officers was carried out on the 21 October 2010. It has been a long time since the previous post stocking survey, and the BP Dam Fish Management Committee is most appreciative that a further survey has eventuated.
The survey was undertaken by the use of Fisheries Queensland’s electro fishing boat only, and no netting apparatus was used. Members of the BP Dam group assisted as deckies during the exercise that was carried out during day and night hours.
As the dam had a major inflow just the week before, survey conditions were not ideal. However, it was decided to continue with the survey as the electro fishing equipment was in the area and the opportunity lost if postponed. With the water level at around 84% at the time of the survey and water still flowing in, the tannin stained water was not conducive for optimum electro fishing. Water temperatures were around 21-23ºC and the dissolved oxygen reading was 5.6mg/L.
Populations and aggregations of bony bream in the upper reaches around standing timber that were sampled were isolated, although when observed there were large numbers. As sampling progressed closer to the lower reaches and shallow weedy banks, larger numbers appeared in schools with plenty of small <50mm juveniles. Largest bony bream sampled was 390mm.
Other species observed included spangled perch, banded grunter, and large long finned eels. There is no doubt that the comparatively low number of species recorded, runs parallel with water quality conditions at the time.
Anglers had been reporting a number of small bass being consistently caught, yet survey results showed a good selection of golden perch in a variety of year classes. These fish were in excellent condition.
Owing to the tannin in the water, it was difficult to observe fish that were ‘rolled’ in the bottom part of the electro probe range, and this may have distorted capture data. It may have been that Australian bass were concentrated in areas of the dam that were not sampled. The abundance of small bony bream assured a reliable food source for stocked fingerlings.
A recent annual survey of storage waters at the Tarong Power Station has once again indicated that the Meandu Creek Dam and Cooling Water Dam are free of Tilapia. Tilapia are present in Boondooma Dam from which Tarong extracts water for its operations. Screens were installed and commissioned in 2002 to prevent the spread of tilapia via the power station facility.
Tarong Energy, who operate the power station commission Fisheries Queensland to carry out surveys to monitor effectiveness of the screens. No tilapia has ever been recorded. Tarong Energy has a program to regularly stock both golden perch and Australian bass in their dams. This stocking is another measure to prevent the presence of unwanted species by increased predation. It is believed that Tarong will be undertaking a further release of fingerlings this season.
It would appear that the installation of mesh screens in water pipelines is an effective manner in which to prevent the translocation of undesired fish species. The Tarong Power Station extracts water from Wivenhoe Dam and Boondooma Dam and both pipelines have screens installed.
Bjelke-Petersen Dam has a reputation for being a very productive recreational fishery. Unfortunately, in recent years it has suffered by extremely low water levels, but still in the main, fished reasonably well. During this period numbers of fingerlings released were quite low and inline with existing water levels at the time.
But now, circumstances have changed, BP Dam is at 86% (mid October), and conditions are ideal for the release of fingerlings this summer. At a recent meeting of the BP Dam Fish Management Committee, it was decided to order some 450,000 fingerlings comprised of both golden perch and Australian bass.
This stocking and a near full capacity will ensure that BP Dam returns to its glory days of being one of the top recreational fisheries in South East Queensland. – Les Kowitz
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