Reproductive biology, steroid and biochemical profiles of Dentex dentex ovaries in the Eastern Mediterranean in relation to histological structure

This study focuses on reproductive biology in female Dentex dentex, which is a summer multiple spawner with the spawning period extending from late April to June. Females with body length over 35 cm were mature. The GSI value had peak values during May and June. The ova diameter ranged over nine groups (50–700 μm). The relative fecundity ranged from 510 to 1276 eggs per g gutted weight and from 20,409 to 22,595 eggs per 1 cm total length. The histological appearance of the ovarian cycle was divided into five periods. The histological structure of the maturing and ripe oocyte wall shows the presence of five different layers. Baseline of testosterone and estradiol levels was found during the immature and spent, whereas the peak value was found in prespawning and ripe-spawning period. While the maximum total lipid content was in the maturing ovary, the minimum was in muscles of prespawning female. The main polyunsaturated fatty acids n-3 (PUFA) for ovary, liver and muscles were docosahexaenoic (DHA, 22:6 n-3) and eicosapentaenoic (EPA, 20:5 n-3) acids, whereas n-6 (PUFA) were linoleic (18:2 n-6) and arachidonic (20:4 n-6). All together, the present observations gave basic data of the reproductive cycle of female D. dentex required for its successful spawning.