Abstract
Yolk-sac larvae of cod reared under continuous illumination obtained shorter maximum lengths than larvae reared in total darkness. The lengths, however, were uneffected by the rearing temperatures (3, 5, and 7° C). Exept for larvae reared in darkness at 7° C, which were heavier than the other ones, the larvae obtained the same maximum somatic tissue weights at yolk absorption irrespectable of light regime and temperature. Dark adapted larvae reared at 3° C grew faster than the corresponding light adapted ones when fed nauplii of Artemia salina during the first feeding stage. Deviations in lengths and weights under different light regimes are discussed in relation to effects of light on larval energy metabolism and utilization of yolk. Lengths and weights of yolk sac larvae from different groups, reared under identical light and temperature regimes, were compared. Large larvae grew faster and seemed to utilize their yolk supplies better for growth than smaller ones.
