Research Article: Evaluation of some reproductive parameters and feeding habitat of the Caspian roach, Rutilus caspicus (Yakovlev, ۱۸۷۰), in the Caspian Sea (Golestan coastal waters)

A study on the feeding and reproductive habits of the Caspian roach (Rutilus caspicus) in Iranian waters was conducted from April ۲۰۱۶ to March ۲۰۱۷. The stomach contents of ۳۳۰ specimens were analyzed and ۱۰۴ specimens were chosen for detailed investigation. Of these, ۴۷ had empty stomachs, and ۵۷ contained food. The stomach emptiness index peaked in winter (۷۳%) and was lowest in spring (۱۱%). Gastropods were identified as the primary food source, alongside crabs, bivalves, and plant fragments. Reproductive analysis showed the largest mean ovum diameter (۱.۵۰۱±۰.۱ mm) at age ۴ and the smallest (۰.۷۶±۰.۱۵ mm) at age ۲. The gonadosomatic index (GSI) in females ranged from ۰.۰۵ to ۰.۱۰, with spawning beginning in March and lasting until mid-spring. The mean absolute fecundity was ۱۹,۴۶۹ eggs, with ۵۰% of females reaching maturity at ۱۳۸ mm and males at ۱۲۵ mm. A significant linear relationship was observed between fork length, weight, and absolute fecundity (p<۰.۰۵). This research provides valuable insights into the seasonal diet, reproductive biology, and ecological behavior of R. caspicus. The findings are crucial for understanding the species’ role in the Caspian Sea ecosystem and informing its management and conservation.

کلیدواژه ها:

Rutilus caspicus ، Feeding habits ، Nutrition ، Fecundity ، Caspian Sea