بررسي خصـوصيات زيستي، رژيم غذايي و شاخص هاي گناد ي و كبد ي ماهي سوف سفيد (Sander lucioperca) د ر د رياچه سد ارس

Survival of biometrical characteristics,diet,gonad and liver index of (Sander lucioperca) in the lake of Arass Dam

The dam of River Arass was built, on this river, in 1972 , 1973 with coordinates 45°22ʹ of east Longitude and 39°7 North Latitude. Now, there are 27 species and subspecies of Teleosts in the lake behind the dam (Sander lucioperca) with 37.3 percent is the most frequent (species)among (different) species of fish in this lake. In the study 125 fish were collected monthy , and 140 fish were collected in 2004 - 2005. nets and gill net by cast net during 1 year from october 2002 to September 2003 and 140 fish were collected in 2004 - 2005. Specimens were carried to the place determined for biometrics snd after anatomical dissection , their digestive systems and reproduction organs were removed from abdominal cavity and they were fixed in Formalin 10% and were assessed in labratoary. 27 features of biometrics were measured the most important results of which are related to the total length : 34.79 ± 8.52 c.m , the standard length: 31.8 ± 7.47 c.m and the weight of the body : 355.13 ± 295.7 Also , The length - weigth regression relation (p <0.05) has a high correlation (r2=76.3) and bis smaller than 3 whichindicates the fish allometric arowth in this lake. Also fishʹs age is determined according to the scale indicating population in classes 2+ or 5+. According to gonadostomatic Indicator (GSI), in March 20 - April 19, the maximum amount of gonads in femal fish is (5.84) and the amount is male fish reaches (2.41). The indicator of stomach emptiness (28.8) shows that the fish is almost gluttonous. The highest amount of food preference belongs to bony fishes a (62/92 percent), second crab larve (31/46) percent cent and aquatic insects , The indicator of intestine length in this fish is 0.7 shawing that the fish is carnivorous. Also , the average of growth correlation is 729 ± 236.87 (KF).