Reproductive Characteristics and Egg Development in Flounder (Pleuronectes flesus luscus) in the Southern Black Sea

Abstract

Spawning time, total fecundity, egg size, fertilization and hatching rates, and egg development of the flounder, Pleuronectes flesus luscus, were investigated in six wild female broodstock (mean wt 394.4±226.8 g). Spawning lasted 33 days from December 29 to January 30. Mean total fecundity was 171.4±109 x 103 eggs per female. Newly ovulated eggs were spherical and buoyant, with a diameter of 1.075-1.213 mm (avg 1.156±0.025 mm), a colorless transparent chorion, a slightly yellowish unsegmented yolk, and a narrow perivitelline space, without an oil globule. Fertilization and hatching rates were 17.2±15.7% and 51.5±27.6%, respectively. Hatching occurred after 117 h of incubation at 9.8-11oC. There were variations in egg size between batches, with the size tending to decrease during the spawning season (p<0.05).