Reproductive biology of the broad-snout [Chondrostoma holmwoodii (Boulenger, 1896)] in Tahtali Dam Lake, Izmir, Turkey

The study aimed to determine the reproductive characteristics of the broad-snout Chondrostoma holmwoodii population (spawning season, number of eggs and first age of sexual maturity) in order to assess the population status in the Tahtali Dam Lake reservoir. A total of 1208 specimens were examined of which 72.1% were females and 27.9% males (female: male ratio = 1 : 0.40); the percentage of males, however, declined in the higher age classes (IV and V). The monthly determined gonadosomatic index indicated that the peak reproduction period of the species is in April and early May. The study covered age classes I-V, with specimens at age II reaching maturity. The total number of eggs per female varied from 8000 to 41 700, the mean number of eggs increasing proportionally with age of the spawner. Egg diameters also increased during the 5-month ripening period from December to April.