Investigation of Some of the Growth and Reproductive Parameters of Common Kilka Clupeonella caspia (Svetovidov, 1941) in Southern Caspian Sea (Mazandaran Zone)

The present research aimed to study the growth and reproductive parameters of common Kilka Clupeonella caspia in southern Caspian Sea in 2010. After measuring the length and weight of 3774 samples, they were dissected, sex determined and female gonads were weighed. Sexual maturity classification was carried out based on six stages. Age was determined using sagitta otoliths. Length-weight relationship was (R2=0.918). Growth parameters were (L∞=128.7mm, k=0.41yr-1, t0=-0.59yr). Age composition was constituted of 6 age groups, including 1-6 years. Age average was 3.27±0.09 years. 3 years old fish were the largest age group, composing 45.24% of the catch population. Male: female ratio was 1: 0.779 and males were dominant. Study of sexual maturity stages and GSI showed that common Kilka spawning begins in February and the peak was in May and June. Survival rate was 0.239 yr-1. Natural and fishing mortality coefficients were 0.448 yr-1 and 0.983 yr-1. The exploitation rate calculated up to 0.687 indicating the species over fishing. Our results showed that the mean length and weight of common Kilka population has increased but the mean age decreased during the last years.