Survey on reproduction and growth parameters of bigeye kilka Clupeonella grimmi Kessler, 1877 in southern parts of the Caspian Sea

The present article aimed to study on growth parameters and reproduction of bigeye kilka Clupeonella grimmi in southern waters of the Caspian Sea. In this study which has done during 2010, 298 samples were fortnightly collected from fishing landing site (Babolsar harbor). After measuring the length, weight and sex determination, the samples were dissected and female gonads were weighed. Sexual maturity classification was carried out based on six stages in ovarian development. Age determination has done using sagitta otoliths. Results were compared with the previous years. Growth parameters for females were (L?=148.5mm, k=0.36 yr-1, t0=-0.92 yr) and for males were (L?=132.1mm, k=0.89yr-1, t0=-0.75yr). Length-weight relationship in females was (R2=0.812) and in males was (R2=0.840) indicated that the growth pattern was positive allometric in both sexes. Age composition of females was constituted of 6 age groups, including 2-7 years and in males was 5 age groups, including 2-6 years. Age average of females and males were 4.09±1.27 and 3.50±1.08 year, respectively. In females, age 4 was the largest age group, composing 28.30% of the catch population and for males, age 3 was the largest age group, composing 55.56%. male: female ratio was 0.656: 1 and females were dominant. Study of sexual maturity stages and GSI showed that bigeye kilka can spawn during the year entirely. The most spawning occurred from November to April. Our results showed that bigeye kilka population structure has been older and their length and weight increased during last decade. According to the growth parameters of this species and comparing with previous years, bigeye kilka has not significantly been affected by the Caspian Sea pelagic changes due to inhabiting in deep regions.

Clupeonella grimmi – Caspian Sea – growth – reproduction - age