Effect of photperiod on the culture of early-stage phyllosoma and metamorphosis of spiny lobster (Sagmariasus verreauxi)

This study examined the effects of photoperiod on the survival, growth, feeding and development of early and late-stage spiny lobster, Sagmariasus verreauxi. The effects of five photoperiods (0, 6, 12, 18 and 24 h photophase) were examined in larvae from hatch to instar 5. Phyllosoma at 6 h photophase grew significantly larger, however, significantly fewer survived. They also ingested fewer Artemia which suggested that the observed inverse relationship between survival and growth may have been a result of cannibalism. Phyllosoma cultured in continuous light were significantly smaller, and moult-stage development was slower, possibly due to an imbalance in energy uptake and consumption due to prolonged activity. Development of phyllosoma was also slower in the dark. The results suggested that a light: dark regime is important for early-stage phyllosoma and a photophase of 12 to 18 h is recommended for culture. The effects of four photoperiods (6, 12, 18 and 24 h photophase) were examined in late-stage larvae (instar 15 to17) to metamorphosis. Significantly more phyllosoma attempted metamorphosis at 24 h photophase. Greatest survival at metamorphosis and overall best pueruli survival, size and mass occurred at either 18 or 24 h photophase. The results provide further evidence that a long, or a shift to a longer photoperiod, promotes more and improved metamorphosis in culture. Long photophase during late-stage development can increase pueruli production by 20% which is important for improving culture efficiency given the long and resource intensive phyllosoma rearing phase.