Australian Bass Breeding Trial

Starting in August 1998, Native Fish Australia commenced a series of breeding trials at the NFA (Victoria) Native Fish Hatchery on Australian Bass Macquaria novemaculeata.  This was partly in response to a request from NFA (Far East Gippsland) who have been attempting to start a re-stocking program in the Snowy River for some time and partly as a simple recognition that little work has been done with bass from the Southern parts of the continent and it is considered that stocking and re-stocking efforts in Victoria would be better accomplished with fish bred from local stock.

The main problems addressed with the now completed Phase 1 trials were acquisition of suitable brood stock, salinity levels, temperature regime and food supply for the fry.   NFA (Far East Gippsland) had provided a number of Snowy River fish to the hatchery that had at the time of the trial not reached breeding condition.  However, a number of fish were obtained with fisheries assistance from a commercial fisherman in the Gippsland Lakes and these were used in the trial.  The Snowy River fish will be used in a later breeding attempt during which it is hoped that a useable number of young fish will be produced.

Taking an egg sample.

On the 14th August 1998, the female fish was first injected with hormone in order to induce ovulation.  Over the next 48 hours follow up injections were given.  Egg samples were taken after a suitable period of time and tested under a microscope at intervals until judged to be at the optimum condition for fertilisation.

The following series of photographs show egg development from the period commencing 1700 hours on the 17th of August 1998 until 0915 hours on the 18th.

17th August 1998 - 1700 Hrs

17th August 1998 - 2000 Hrs

17th August 1998 - 2145 Hrs

18th August 1998 - 0125 Hrs

18th August 1998 - 0410 Hrs

18th August 1998 - 0720 Hrs

18th August 1998 - 0910 Hrs

18th August 1998 - 0915 Hrs

When the eggs are ready, they are stripped from the female and fertilised in a bowl containing a spawning solution with milt from two male bass.  The fertilised eggs are then placed in a pre-heated spawning tank.

The following series of photographs show egg, larvae and fry development for the period commencing the day after fertilisation until the end of the breeding trial.

19th August 1998

24th August 1998

28th August 1998

4th September 1998

16th September 1998

19th September 1998

At the completion of the trial, the salinity in the spawning tank was reduced so that surviving fry could be transferred to a pond for further growing out.

Whilst the number of fry produced in this trial was relatively low compared with the breeding potential for this species, it has allowed NFA to identify factors that need to be better controlled in future breeding exercises.  It is reasonable to expect that NFA will be able to produce worthwhile numbers of bass that would be made available for our re-stocking program (with Victorian Fisheries approval, of course).