EFFECTS OF SALINITY ON YOLK-SAC LARVAE OF ATLANTIC HALIBUT (HIPPOGLOSSUS-HIPPOGLOSSUS L.)

Larvae of Atlantic halibut (Hippoglossus hippoglossus L.) were transfe rred to nine different salinities (range 20-42 ppt) immediately after hatching, or to five different salinities (range 24-39 ppt) at day 30 post-hatching (p.h.) The experiments were terminated 49 days p.h. (at 5 degrees C); i.e. at first feeding. When newly-hatched larvae were in troduced to different salinities, the highest survival rates (69-90%) were obtained at 27-32 ppt. A high yield of normally developed larvae was only obtained within a limited range of salinities (29-34 ppt). Th irty-day-old larvae tolerated a wider range of salinities than newly-h atched larvae, and only larvae transferred to the highest salinity (39 ppt) exhibited significantly reduced survival and yield of functional larvae. Myotomal height, larval dry weight and yolk volume were littl e influenced by the rearing salinity in either experiment. The buoyanc y of halibut larvae was influenced both by the rearing salinity and by larval age. (C) 1997 Published by Elsevier Science B.V.