خصوصيات ريخت سنجي و رژيم غذايي ماهي اسبله (Silurus glanis) در رودخانه چمخاله لنگرود

Morphometric and feeding behavior {Silurus glanis) in Chamkhaleh river

In the study 127 specimens of Silurus glanis were caught, monthly , by means of gill net and cast nets. All specimens were studied and measured for 19 morphological features including total length, standard length, .... Also, to study diet the digestive system each specimen was removed from abdomen, through anatomical dissection and was fixed by formalin. The hard radius of pectoral fin was removed , in order to determine the age, and it was found that the fish in this set belong the age group 7 and fish at age 3-4 are the most abundant ones. The average, of weight was (906.60) with standard deviation (777.04), and the average of fish total length with standard deviation 10.21 was 48.55 and length-weight relation was obtained using regression model. There was a meaningful cooperation between total length and (body) weight. (P<00.1) but there was no meaningful cooperation between weight age and length-age. The average of stomach indicator: (272.43) intestine indicator: (51.26) and growth correlation (602.91). there were food elements in fish s {silurus glanis) digestive system including frogs, crustacean, insects, water plants, mice, different kinds of fish and aquatic birds. The most frequent food was related to kind of teleoste (56.66%) and the least frequent food was related to mice, aquatic birds and plants (3.12%). The obtained results show that the indicator of intestine length to the body length, was calculated less than 1 indicating that Silurus glanis in Chamkhaleh River is carnivorous.