A comparative study on reproduction of kilka species (Clupeidae) in southeastern parts of the Caspian Sea

Abstract

The aim of the present study was to investigate the reproduction of three species of kilka, including common, anchovy and bigeye kilka in the southeastern waters of Caspian Sea. This study was conducted during 2010 and 6476 specimens were fortnightly collected from fishing landing site. Body weight and fork length were measured. The samples were dissected and female gonads were weighed. Sexual maturity classification was carried out based on six stages in ovarian development. Age was determined using sagitta otoliths. Results were compared with the previous years. Male: Female ratio in common, anchovy and bigeye kilka were 1: 0.779, 0.569: 1 and 0.656: 1, respectively. Study of sexual maturity stages and GSI showed that common kilka spawning began in March and ended in July with the peak in May. Spawning period of anchovy kilka was more extensive than common kilka and take place from April to November with a peak in November. Bigeye kilka spawned during the year entirely. Its spawning occurred intensively during the autumn with a peak in October. Our results showed that M: F ratio differs during the year which is related to their reproduction. The reproduction scheduling of kilka species comparing with the previous years had some changes but has not significantly been affected by the Caspian Sea pelagic changes.