بررسي تغذيه كيلكاي معمولي در حوضه جنوبي درياي خزر(سواحل استان مازندران)

An investigation on the feeding behavior of common kilka {Clupeonella cultriventris caspia) in the southern Caspian Sea, Mazandaran Province, Iran

Monthly samples of common kilka {Clupeonella cultriventris caspia) were collected at night on board of kilka fishing vessel during the years 2004-2005 in Mazandran province. The decreasing kilka population in the Caspian Sea and the associated economic loss of fisheries sector were the main reasons encouraging the research. The stomach contents of common kilka and biotic and abiotic factors at the fishing areas were examined in this project. The length and weight of common kilka fluctuated between 100±7 to 113±5mm and 7.0±1.9 tol0.3±1.0g, respectively. The highest feeding activity was observed in April with 280±153 individuals of prey weighing 2.9±1.6mg per fish consisted of 7% Acartia and 93% Balanus nauplii and cipris. The zooplankton population taken in during March to September was composed of Balanus nauplii and cipris (67% to 100%) but the biomass of copepoda (Acartia) was dominant from October to February. We observed that with increasing temperature in spring, Balanus reproduced and the stomach contents of kilka comprised more than 90% Balanus cipris and nauplii. In winter, Copepoda was observed more in stomach contents of kilka while Balanus decreased.