A preliminary investigation of the relationship between otolith weight and age for Chondrostoma regium (Heckel, 1843) (Teleostei: Cyprinidae)

To our knowledge, no study is available on the relationships between otolith mass and age as well as body weight and length of Chondrostoma regium (Heckel, 1843) in the Zayandeh River, hence the present study attempted to examine this rather simple, efficient and cost-effective approach to contribute in providing more objective information required in age-related studies of this species. During March-April 2017 random samples of C. regium were collected by a river seine in the Zayandeh River. Sampled fish ages were between 2 to 5 years and ranges of total length, body weight and otolith mass averages of samples were 82.2-161.6mm, 5.35-42.35g and 4.1-7.3mg, respectively. As the fish grow, total length, body weight and otolith mass averages showed a clear increasing trend. The results revealed significant positive relationships between variability of body length and otolith weight (P<0.05) as well as variability of body weight and otolith mass (P<0.05) of C. regium. Furthermore, an obvious significant increasing trend of otolith mass with age increment (P<0.05) is found. The average weights of otoliths in the present study increased with age, length and weight which evidently confirms that the otolith mass increase in C. regium is in compliance with somatic growth through the ontogenetic processes.