بررسي شاخص هاي رشد و تغذيه گل آذين ماهي (Atherina boyeri caspia Eichwald، 1838 ) در سواحل جنوب شرقي درياي خزر

Characteristics of biological influence on the growth and feed index of the sand smelt fish (Atherina boyeri Risso, 1810) on the southeast coast of the Caspian Sea

هدف از اين پژوهش مطالعه بررسي برخي از شاخصهاي بيولوژيكي ماهي گل آذين خزري در سواحل جنوب شرقي درياي خزر ( بين گهر باران ساري و نيروگاه نكا) واقع در آبهاي استان مازندران است. بدين منظور، بعضي از ويژگيهاي زيست شناسي از قبيل سن، جنسيت، نسبت جنسي، پارامترهاي رشد و تغذيه مورد بررسي قرار گرفت. ميانگين (±انحراف معيار) طول كل و وزن ماهيان بترتيب 1/21±8/48 سانتيمتر و 1/48±3/81 گرم بوده است. رابطه طول و وزن با معادله 2/866TL008/0=W، الگوي رشد آلومتري منفي را براي اين ماهي در اين منطقه نشان داد. معادله رشد وان برتالانفي براي كل ماهيان ](1/61+t)0/27-[1-e7/134Lt= محاسبه شد. نسبت جنسي نر به ماده 85:1/1 بود، كه تفاوت معني داري از لحاظ آماري در آنها ديده شد (0/001 ;P<20/61X2=). شاخص گناد جنسي (GSI) با افزايش سن، كاهش يافته و اوج منحني آن در اسفند ماه ديده شد. فاكتور وضعيت (CF) با افزايش سن، كاهش يافت و اوج منحني آن در ماه ارديبهشت ديده شد. در ميان شاخص هاي تغذي

Objective of the present study examines some biological characteristics of the sand smelt in the southeast coast of the Caspian Sea (between of Gohar Baran and Neka power house) in Mazandaran province. Accordingly, some of the biological characteristics such as age, sex, growth and nutritional parameters were studied. The mean (±SD) total length and weight were 8.48±1.21 cm and 3.81±1.48 kg, respectively. There is a significant correlation between them (P<0.001). The length and weight of relationship (exponential regression) with equation W= 0.008 TL2.866, negative growth pattern is show for fish in the area. Van bertalanffy growth equation was determined Lt=13.47[1-e-0.27(t+1.61)] for the entire fishes. The sex ratio was between of male to female 1:1.85, Statistically significant differences were observed in them (X2 =20.61 ;P<0.001). Increase with age the rate of decreased gonad sexual index (GSI) and curved top has been accessed in the month of March. Increase with age the rate of decreased Condition Factor (CF) and curved top has been accessed in the month of May. Between the nutritional parameters of index were studied, the relative length of gastrointestinal of index (RLG), the void stomach of index (VI) and intensity of food (IF). Accordingly, RLG index with a mean (±SD) 0.46±0.06 is indicative of a carnivore, VI of index with 45 percent of the stomach is empty, indicating is condition relatively polyphagous and middlephagous and also IF of index with a mean (±SD) 535±221.21 showing optimum limit fish food for the area.