V. Puvanendran, J.A. Brown
Abstract:
Different experiments carried out in our laboratory on larval cod showed that inappropriate light intensities and photoperiod affect the growth and survival. We reared Atlantic cod larvae at different light intensities (300, 600, 1200 and 2400 lux) and photoperiod (12L:12D, 18L:6D and 24L:0D) in the laboratory. Larvae were reared from hatching to 42 days post-hatch on rotifer and/or Artemia. Larvae reared at 1200 and 2400 lux were significantly larger than the others. Larvae reared at 1200 and 2400 lux swam and foraged significantly higher than larvae reared at 300 and 600 lux. Larvae reared at 2400 lux had the highest survival (41.5%) followed by 1200 (27%), 600 (12%) and 300 lux (5%) at the end of the experiment. Among the three photoperiods tested, larvae reared at continuous light had higher growth and survival than larvae reared 12L:12D and 18L:6D. Higher survival of larvae at day 14 post-hatch in 2400 lux (54.5%) and 24L:0D photoperiod (40%) compared to other treatments indicate the importance of light during the early larval stage.
(Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, NF A1C 5S7, Canada)