Age and growth of brond-snout, Chondrostoma regium in Beheshtabad River of Chaharmahal & Bakhtiari Province of Iran (Teleostei: Cyprinidae)

The age and growth parameters of the brond-snout, Chondrostoma regium in Beheshtabad River of Chaharmahal & Bakhtiari Province were investigated during April 2013 to April 2014. The males ranged between 8.04-22.10cm and 5.20-105.00g. The females ranged between 7.84-23.15cm and 8.70-155.00g. Males were categorized in age classes 1+5 and females in age classes 1+6. The age class 3 was the dominant one in the whole samples. The length-weight relationship for males, females and all individuals was as W=0.0089L3.045 (r2=0.95), W=0.0082L3.109 (r2=0.85) and W=0.0107L3.000 (r2=0.92), respectively, indicating a positive allometric growth pattern for the females and an isometric growth for the males and all fish.
The age-length and age-weight relationships in males and females were estimated as Lt=26.23[1-e-0.267(t.483)], Wt=160.77[1-e-0.267(t.483)]3.045 and Lt=31.89[1-e-0.148(t.067)], Wt=266.11[1-e-0.148(t.067)]3.109, respectively. The growth performance index (Ф') value was 3.84 in males and 2.18 in females, indicating a faster growth rate in males. The mean condition factor was 1.02±0.01 for males and 1.14±0.02 for females. The relative length of gut was 1.18±0.05 for all fish, indicating a herbivorous habit for this fish. The highest mean feeding intensity of males was in July and the lowest in March and April. In the female, the highest was in January and the lowest in June. The highest mean value of Gut vacuity index of males and females was in the spring and the lowest in summer. About 55% of the studied stomachs were full. The highest number of empty stomachs was in May (80%) and the lowest in July (32%). Based on the mean Gut vacuity index (48%), this fish is considered a medium feeding fish (40