The effect of photoperiod on larval culture performance of two marine finfish species

Light can have significant impacts on larval growth and survival of many marine fish species. Here, we study the effect of photoperiod on larvae from captive populations of two marine finfish species, California yellowtail (CYT; Seriola lalandi) and white seabass (WSB; Atractoscion nobilis). Two photoperiod treatments were tested: 12 h light and 12 h dark (12-L), and 24 h light and 0 h dark (24-L). CYT larvae were significantly heavier (240 ± 16 μg dry weight) in the 24-L treatment group than the 12-L group (155 ± 25 μg dry weight) at 10 dph. Similarly, WSB were significantly heavier (685 ± 77 μg dry weight) in the 24-L treatment group than the 12-L group (455 ± 44 μg dry weight) at 18 dph. CYT larvae also had significantly greater survival (16.6 ± 6.2%) in the 24-L treatment over the 12-L conditions (7.6 ± 4.9%). In contrast, WSB larvae showed no significant difference in survival between treatments. Food consumption was significantly greater in the 24-L treatment for both species up until 6 dph, after which time no difference was observed. Swim bladder inflation rates were not significantly affected by the photoperiod treatments. These results indicate that photoperiod is a significant factor in early larval performance for both CYT and WSB, although it is unknown if continuous light becomes detrimental as larvae develop.

► Continuous light produced larger California yellowtail and white seabass larvae.
► Survival for California yellowtail was higher under 24 hr light conditions.
► Swimbladder inflation was not changed with the change in photoperiod.
► 24 hr light is beneficial for these species through larval rearing.