ABSTRACT
Halibut larvae hatch in a premature form. Eyes, mouth and digestive system are incompletely developed at hatching, and the newly hatched larvae are very sensitive to environmental stress. At a temperature of 4°C, the larvae will depend on their yolk sac resources for 45–50 days before they start to feed. Compared to most other marine fish, this is a very long yolk sac period. Several experiments were carried out to examine the effects of different environmental factors such as temperature, salinity, light, mechanical stress and tank materials on survival and development of the larvae. Different salinities are commonly used as a routine in halibut hatcheries, but the knowledge about effects of different salinities on yolk sac larvae of halibut is scarce. Newly hatched larvae were transferred to experimental units of different salinities. High frequencies of deformed larvae at the end of the yolk sac stage may be caused by negative effects of the materials used in the incubation units.
