O. Karlsen, A.B. Skiftesvik, J.V. Helvik-1998
Aquaculture Research, 29 (12) : 899-911 (from Current Contents)
Abstract:
The growth and activity of Atlantic halibut, Hippoglossus hippoglossus L., yolk-sac larvae exposed to light of differing intensities and wavelengths were investigated every fifth day. The experiments were conducted at 6 degrees C from day 1 until day 34 post hatch. Four intensities of constant white light (2.0, 0.3, 0.03 and 0.005 mu E/m^2/s, lambda(max) 590 nm), and constant coloured light of equal intensities (0.03 mu E/m^2/s) in the blue, green and red spectrums (lambda(max) 450, 560 and 670 nm, respectively) were used. In addition to a control treatment in constant darkness, one treatment was incubated in a 12:12 h light:dark photoperiod. The light treatments did not have any discernible effect on the total length, myotome height, dry weights or yolk conversion efficiencies. The most intense white light resulted in an increased activity on days 24 and 30 post hatch, resulting in a temporarily reduced length and myotome height for the larvae in these groups compared to the other treatments. Larvae from all treatments were of the same size 34 days post hatch. The dry weights of the larvae and yolk-sacs were unaffected by light treatment. The activity increased independently of light treatment until 120 degree-days, and thereafter, the strongest white light resulted in a temporarily increased activity. The distribution of activity changed independently of light regime in the beakers during development.
(Inst Marine Res, Austevoll Aquaculture Res Stn, N-5392 Storebo, Norway)