Effects of photoperiod and light intensity on initial swim bladder inflation, growth and post-inflation viability in cultured striped trumpeter (Latris lineata) larvae

Transient physostomes often fail to complete initial swim bladder inflation in culture and display reduced survival and growth. Three experiments were conducted in replicate 200-1 tanks to determine the effects of photoperiod and light intensity on initial swim bladder inflation, post-inflation viability (surviving larvae with inflated swim bladders) and growth in striped trumpeter (Latris lineata) larvae. Both photoperiod and light intensity were found to affect initial swim bladder inflation, growth, survival and post-inflation viability of striped trumpeter larvae. Higher initial swim bladder inflation was promoted by providing a dark-phase before and during initial swim bladder inflation. Swim-up behaviour where larvae gulped air at the water surface to fill their swim bladder was predominantly observed during the dark-phase. In Experiment 1, a 12L:12D photoperiod was inferior to either a 18L:6D or 24L:0D photoperiod for larval growth. In Experiment 2, initial swim bladder inflation was higher in larvae reared under a light intensity of 4 μmol s-1 m-2 compared to 40 μmol s-1 m-2. From Experiment 3, a 18L:6D photoperiod provided higher post-inflation viability than either 24L:0D, or a photoperiod combination of 24L:0D from stocking, changing to 21L:3D at the onset of initial swim bladder inflation. However, different optimal photoperiods for initial swim bladder inflation (18L:6D) and survival (24L:0D) lowered post-inflation viability in striped trumpeter. The results suggest a photoperiod of 18L:6D with a light intensity of 4 μmol s-1 m-2 is the best combination for post-inflation viability. © 2003 Published by Elsevier Science B.V.