Biological assessment of common eagle ray, Myliobatis aquila (Linnaeus, 1758) from the Northeastern Mediterranean (Saros Bay), Türkiye

Serdar ÖZTEN, Cahide Çiğdem YIĞIN, Ali İŞMEN, Koray CABBAR


In this research, total length-frequency distribution, length-weight relationships, sex ratios, age, growth, reproduction and feeding habits of the common eagle ray (Myliobatis aqulia) were investigated using 85 specimens from the Northern Aegean Sea. Females made up 48.2% and males 51.8% of the total individuals studied. The F:M sex ratio was determined as 1:1.07. The total length of females and males ranged between 30.7 and 121 cm (Disc width: 21.7 cm-100 cm), and between 29.5 cm and 100 cm (Disc width: 21.5 cm-56.1 cm) respectively. The total length (TL)-total weight (TW) and disc width (DW)-total weight (TW) relationships were described by the equations; TW=0.0012TL3.20, r2=0.87 and TW=0.0081DW3.17, r2=0.98, respectively. Age data derived from vertebrae readings were used to estimate the growth parameters of von Bertalanffy equation: L=138.59 cm, K=0.90 y-1, t0=-0.09 y for males and L=164.08 cm, K=0.95 y-1, t0=-0.08 y for females. The maximum age were 10 for males and 16 females. Using gonadosomatic index and gonadal macroscopic observation, the spawning period was lasted throughout the year. Stomach content analysis showed the most-preferred prey to be mollusca (47.86% IRI) and teleostei (14.02% IRI).

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