CST is moving to the capacity for a 5,000 ton per annum sustainable YTK business by 2020. To underpin this growth in the YTK industry it is critical that the hatchery production efficiency and quality of fingerlings produced are improved.
This project will direct investment in skilled personnel and resources to increase our understanding of critical factors that can be manipulated for improved yield of YTK juveniles and lower production costs by refined culture conditions to achieve reliably higher survival, higher swimbladder inflation rate and lower incidence of skeletal deformities.
The project fits within the Seafood CRC outputs and milestones, as follows, toward the outcome of a 'substantial increase in the production and profitability of selected wild-harvest and aquaculture species'.
1.1 (Output) Technically verified new aquaculture production systems on a commercial scale
1.1.2 (Milestone) Key researchable constraints identified and characterised in at least two new production systems
1.1.3 (Milestone) Key researchable constraints successfully addressed in at least two new production systems
Three significant issues were identified in YTK larval rearing over the last 3 years that present bottlenecks to hatchery production efficiency. These include:
1. low survival (potentially linked to high microbial load in live feeds and larval cultures, sinking of older larvae, variable temperature which is constrained by ‘outside’ rearing conditions under ambient natural sunlight)
2. low swimbladder inflation rates (associated with changed husbandry conditions; upwelling, mister fans, skimming efficiency, algae pastes, larval health/nutrition)
3. high rates of jaw deformity (potentially linked to quality and quantity of enriched rotifer and Artemia diets, temperature)
The project addresses all three issues, with a focus on applying results from previous research at medium and commercial-scales (light intensity and quality, and temperature, live feed regimes) and investigating larval nutrition and photoperiod at a small-scale.
Final report
Clean Seas Tuna is the largest commercial hatchery producer of Yellowtail Kingfish fingerlings in Australia. Following three years of research (2007-2010) into larval rearing issues, the company still experienced variability in results between the two hatcheries, Port Augusta and Arno Bay, between runs within hatcheries, and between individually stocked larval tanks (even those stocked from the same egg batch). 2009 was particularly challenging compared to the previous two years with an increase in skeletal malformations (jaw deformity from 20-25% to > 50%), decrease in survival (from >10% to 8%), and decrease in swimbladder inflation (from 99% to 80%). This 1 year project built on and applied, at a commercial scale, the results of the previous projects (SfCRC 2007/718 and 2009/749). The project was designed to support improved Standard Operating Procedures and test promising alternative rearing conditions, identified in previous research (especially temperature and artificial light), at a medium-scale in Arno Bay and Proof-of-Concept (commercial-scale) in both hatcheries. Funding was requested to invest in skilled personnel, upgrade systems, support key national collaboration, and provide operational costs at partner organisations.
