Abstract
Size and buoyancy of flounder eggs are markedly altered when ripe females are transferred from 34.5 ‰ to 5 ‰ salinity. After 3 weeks in low salinity the buoyancy is reduced from 31 to 23 ‰ salinity and the egg-volume increased with 17 %. The results are discussed on the basis of osmotic adjustment of the internal fluids. Flounder eggs from Bergen never develop in salinities lower than 11 ‰. Eggs from Finnish waters, 6.5 ‰ salinity, are fertilized in this salinity and develop at the bottom. Ecological aspects are discussed.