The Biological Properties of the European conger eel Conger conger (Linneaus, 1758) in the Central Aegean Sea
Project no. 1133 · Status: Kapanmış · 2015
Summary
The study were carried out to determine some of the biological properties of the uropean conger eel Conger conger (Linnaeus, 1758) like length-weight relationship, sex ratio, age, condition and diet in the Aegean Sea. The study material were obtained from the field studies between October 2015 and November 2017 and a total of 100 specimens were caught, 67 of them from Çandarlı Bay by angling and 33 from commercial trawlers which operate off Çeşme (Izmir) coasts in the Aegean Sea. Length (TL, cm), weight (TW, g) and gonad weight of the samples were measured within in accuracy of 0.1 cm and 0.01 g by a scaling ruler and a digital scale respectively. The length-weight relationship were estimated by the formulae W= aLb. Otoliths were removed and stored in eppandorf tubes as dry for aging of the specimens and gonads were examined histologically for sex determination. Stomach contents were fixed in 4% formaldehyde solution. Gonadosomatic index (GSI) and condition factor (CF) values were calculated for determining the status of the reproduction and condition of the species. Prey groups in diet composition were interpreted by results of numerical (%N), frequency of occurance (%F), weight (%W) and Index of Relative Importance (%IRI) values. The mean length and weight of the specimens were estimated as 73.3 cm and 1046.4 g respectively and the age composition were found between II and VI. The length weight relationship of the samples were W=0.0008L3.206 (r2=0.970). All fishes were determined as female by histological observations. According to the GSI values in seasons, the spawning period of the species are late winter and spring in the area. Beside that the condition factor was not changed in seasonally. It was found that, conger eel are mainly feeding on 3 prey groups namely, Teleostei, Crustacea and Mollusca