Reproductive biology of Caspian goby, Neogobius caspius (Eichwald, 1831) in the southern Caspian Sea (Noor beach)

Abstract

This study provides fundamental information on some key aspects of the reproductive biology of Neogobius caspius, a Caspian Sea endemic, poorly studied Gobiidae fish species. In total, 222 specimens were captured monthly from Noor coastal waters in southern part of the Caspian Sea from April to October 2016, while water parameters (temperature, salinity and pH) were monitored weekly. Gonadosomatic and hepatosomatic indices suggested that the reproductive period of this species was in April to May. Peak of Fulton and Clark’s condition factors appeared in April and May for female and male specimens, respectively, then a declining trend appeared until June that remained constant until the end of October. Absolute fecundity ranged from 418 to 1798 oocytes per individual (mean: 1013±357 (SD) oocytes, n=41), which was highly related to the length and weight of fish and weight of gonads. Oocyte mean diameter ranged 35.85±11.80 µm in immature stage to 1103.86±172.01 µm in mature stage. Five stages of maturity for female and four stages for male specimens were described based on macroscopic features and histological description. N. caspius appeared as an iteroparous and a batch spawner species, producing more than one oocyte clutch in a single reproductive season.