Addressing causes of early mortality in hatchery produced southern bluefin tuna larvae. Chapter 9: the effects of in-tank lighting on the early behaviour and performance of yellowtail kingfish larvae

High levels of variability in the survival, growth and malformation rates of YTK larvae (produced by different hatcheries, or even between different hatchery runs at the same hatchery), have been problematic in trying to better understand the causes of the bottleneck issues in YTK larval rearing. Some of the key parameters that have differed between hatchery sites or runs with variable rearing outcomes include the level of tank illumination, tank wall colour and pattern and especially the amount of reflected light coming off the walls. One potential way to address this is to use in-tank lighting. One experiment was carried out to see if an in-tank LED light could reduce walling behaviour in early stage YTK reared in standard glossy green tanks. The indications were that the in-tank light setup used in this study did not perform as well as the Granite tanks for YTK larvae up to 4 dph.