ENHANCED 1ST FEEDING OF HALIBUT LARVAE (HIPPOGLOSSUS-HIPPOGLOSSUS L) IN GREEN WATER

Feeding incidence, survival and growth rates of Atlantic halibut larvae (Hippoglossus hippoglossus L.) were compared during first feeding in a suspension of natural phytoplankton (green water) vs. in filtered (clear) water. The larvae were fed nonenriched Artemia instar II. Feeding incidence at day 3 was 47% in green water and 0% in clear water. Both growth and survival were higher in green water compared to clear water. From a total of 2250 halibut larvae in the green water tanks, 684 survived to the end of the experiment (day 21). The corresponding number for the clear water tanks was 57 out of 4500. The results did not indicate direct or indirect nutritional effects of the phytoplankton, and no improved performance could be related to the quality of Artemia. Other aspects of green water, such as turbidity and effects on the light regime, are discussed in relation to perceptive distance and behaviour of fish larvae.