Reproductive condition and ovarian atresia in the common kilka (&lt;i&gt;Clupeonella cultriventris&lt;/i&gt;) from the Caspian Sea years after a dramatic outbreak of the comb jelly fish (&lt;i&gt;Mnemiopsis leidyi&lt;/i&gt;)

Ali Bani,Narjes Karimi,Shahram Abdolmalaki

doi:10.3989/scimar.03562.01a

Abstract

SUMMARY: To assess the reproductive condition of the common kilka, Clupeonella cultriventris, the somatic condition and reproductive characteristics were studied by histological analysis. A total of 800 specimens from the Bandar Anzali coast on the Caspian Sea were sampled. The gonadosomatic index (GSI) for females and males attained maximum values in May in the first period of sampling and in March-April in the second period, suggesting temporal variations in spawning activity. The pattern of oocyte frequency distribution demonstrated that the common kilka is a batch spawner with group-synchronous oocyte development. The estimated relative batch fecundity was 6718 oocytes g–1. A low level of atresia (4.7%) during the spawning season showed that this species was in optimal somatic condition. This weakens the hypothesis that abundance of the ctenophore (Mnemiopsis leidyi) in the Caspian Sea, as a food rival for kilka, influences the body condition and subsequently the reproductive capability of this species.

Highlights

The common kilka (Clupeonella cultriventris) belongs to the Clupeidae family and is a commercially important species in the Caspian region
SUMMARY: To assess the reproductive condition of the common kilka, Clupeonella cultriventris, the somatic condition and reproductive characteristics were studied by histological analysis
The pattern of oocyte frequency distribution demonstrated that the common kilka is a batch spawner with group-synchronous oocyte development

Summary

Introduction

The common kilka (Clupeonella cultriventris) belongs to the Clupeidae family and is a commercially important species in the Caspian region. It lives in the coastal zone at a depth of less than 50-70 m (Prikhodko 1981, Pourgholam et al 1996, Fazli and Besharat 1998). Overfishing and the competition for food of clupeid fish by comb jelly fish (Mnemiopsis leidyi), an introduced alien ctenophore in the Caspian Sea, are recognized as causative factors for the considerable decline in abundance of clupeid fish (Bilio and Niermann 2004). Heavy competition for zooplankton from M. leidyi causes starvation in the clupeid stocks (Kideys 2001)

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