در سواحل جنوب شرقي درياي خزر A.GULDENSTAEDTI BRANDT 1833 و چالباش ACIPENCER PERSICUS BORODIN 1897 بررسي عادات غذايي ماهيان خاوياري قره برون

The study of juveniles Acipenser persicus Borodin 1897 and A.guldenstaedti Brandt 1833 diets in southeast of the Caspian Sea,Golestan province, Iran

197 juvenile Acipenser persicus and A.guldenstaedti specimens were collected in the southeast of Caspian Sea during 1997.1999 from beach seines in Minankaleh Peninsula, Golestan Province, Iran. Specimens fixed in 10% formalin and transferred to laboratory, examined by standard methods. Stomach contents determined, possibility and frequency of i prey calculated with standard methods. The percent of empty stomach, prey dominance, resultant index food niches and the cached prey diversity evaluated by specific formula. Results showed that in A.guldenstaedti gammarids and in A.persicus cumacea were the dominant and specific food items. Seasonal changes were observed in food compositions. The percent of empty stomach in two species in autumn and winter were higher and lower respectively in comparison with other seasons. In all seasons the percent of empty alimentary canal in A.guldenstaedti were higher than A.persicus. The food niche width of A.guldensiaedti was less than A. persicus in caught preys. In food overlap, as observed was in the order of highest in winter and lowest in the spring.