High incidences of malformation and low level survival are common during Yellowtail Kingfish larviculture and it has been hypothesised that this is a result of excessive harmful bacterial loads within the culture tanks. The current rate of malformation and survival continues to impact heavily on the price of juvenile kingfish. There is a need therefore, to reduce the incidence of such malformations and increase the overall survival rate to reduce the cost of juvenile production and improve the quality and quantity of fish being put to sea.

The researcher Dr Michael, travelled to the University of Miami’s Experimental Marine Hatchery (UMEH) to work and train under the supervision of Professor Daniel Benetti and alongside his Masters student, Mr Zack Daugherty, the subject of whose thesis is the use of clay particles in larval rearing of Cobia. Over the past 12 months Mr Daugherty has been conducting preliminary trials on the best methods of handling and delivering clay particles to larval rearing tanks.

During the 30 day visit, Dr Michael was able to further develop these techniques with Mr Daugherty prior to conducting a 13 day replicated research trial that assessed the potential bacterial reducing properties of using clay during Cobia larval rearing compared with the standard green water method that uses concentrated nannochloropsis paste. Using clay particles to replace nannochloropsis paste during the green water phase of Cobia larval culture was recently investigated. The results clearly showed that using this media has the potential to greatly reduce bacterial loads within larval tanks and reduce costs associated with purchasing algal paste concentrates.

We have demonstrated that yields of 10 tonnes of fish per hectare cannot be sustainably achieved in static, autotrophic saline (14 ppt) ponds (i.e. ponds dominated by photosynthetic organisms) over a 3-4 month production cycle, despite the removal of settable wastes from the SIFTS. The outcome of this finding was to advise potential industry entrants of this fact and to further investigate alternative options to enable such yields to be achieved.

Our work on integrating heterotrophic pond management techniques (i.e. ponds dominated by bacterial organisms which utilize organic carbon as an energy source) with carnivorous fish production in SIFTS have demonstrated that 15 tonnes per hectare are achievable over a 100 day production cycle. Economic analysis revealed that the profitability of a stand-alone enterprise growing carnivorous fish in SIFTS within heterotrophic ponds would be marginal at 150 tonnes per year of production. The outcomes of these trials have already been used to design further trials on optimizing heterotrophic pond management at the Queensland Department of Primary Industries’ Bribie Island Aquaculture Research Centre. Demonstrating that SIFTS can be integrated with heterotrophic pond management systems creates an opportunity for existing prawn farms using heterotrophic pond management to integrate barramundi farming into their existing operations with minimal changes required to their operations. The McRobert Aquaculture Group are discussing the integration of SIFTS into prawn farming ponds and settlement raceways with the prawn farming industry in Queensland.

The main outcome of our research using NyPa Forage to treat salinised and eutrophied waste is a further project funded by the RIRDC, in which NyPa Forage will be grown on a larger scale in the field and it’s nutritive value determined in livestock in vivo. As a result of our project, NyPa forage is being investigated to fix atmospheric carbon under a carbon credit scheme. The ‘Degree Celsius’ project is a collaboration between Terrain Natural Resource Management and BioCarbon, a private company, who are investigating the carbon storage capability of NyPa Forage in an effort to make valuable use of salt affected lands. 

Keywords: Inland saline aquaculture, Semi Intensive Floating Tank System, SIFTS, barramundi, rainbow trout, heterotrophic pond management, halophytes, NyPa, Artemia

The results of this study show that hatchery-reared Black Bream can be used to enhance the stock of the population of this commercially and recreationally important species in the Blackwood River Estuary in which it has become depleted. An initial trial of different stains demonstrated that alizarin complexone was particularly effective for staining the otoliths (ear bones) of Black Bream. The mark on the otoliths, produced by this stain following immersion of hatchery-reared juveniles, was still visible to the naked eye 3.5 years later. Substantial numbers of the stocked Black Bream, which were introduced into the Blackwood River Estuary, were still living at the end of 3.5 years. On average, these individuals did not grow as rapidly as those in the wild population, and unlike the wild fish, not all stocked Black Bream attained maturity by 4 years of age.

However, they still grew at a rate that was greater than that in some other estuaries and many did reach maturity by 4 years of age. The Black Bream is thus a particularly good candidate for restocking an estuary as it completes its life cycle within these systems in south-western Australia and consequently any stocked fish are unlikely to move into other estuaries in this region. The ease and relatively low cost of culture of Black Bream and its hardiness and restriction to its natal estuary make the restocking of Black Bream a feasible and economically-viable proposition.

This study shows that restocking provides managers with a further and viable option for countering the effects of a decline in a stock of Black Bream in an estuary.

Keywords: This study shows that restocking provides managers with a further and viable option for countering the effects of a decline in a stock of Black Bream in an estuary.