نوع مقاله : مقاله پژوهشی
گروه شیلات، دانشکده منابع طبیعی، دانشگاه گیلان، صومعه سرا، ایران.
عنوان مقاله [English]
Length-weight relationship and some biological parameters of Alosa braschnikowi (Borodin 1904) were studied from coastlines of the Caspian Sea (Guilan Province, Iran). . A total of 103 fish specimens were caught on a monthly basis using gill-net and beach seine net from were sampled from three stations i.e. Astara, Anzali, and Kiashahr. The age range in females (1+-4+) was greater than that of males (1+-3+). The total length of the males and females were 18-42 and 19-42 cm, and the fork lengths were 16-38 and 16-39 cm, respectively. The length frequency varied from 30-34 cm. The weight of males and females were 45-570 and 50-810 g, respectively. The mean total length, fork length, and total weight were 29.26±4.70, 26.88±24.4 and 231.36±130.44 g, respectively. The mean gonadosomatic index of the whole population was 1.64±1.81, where the minimum and maximum values were observed in autumn and spring, respectively. The mean hepatosomatic index and condition factor for the whole population were 0.78±0.34 and 0.083±0.13, while minimum and maximum values were recorded in summer and spring, respectively. Considering that CF>1 is an indicator of good feeding condition, the CF values obtained in this study suggests poor feeding condition for the species. The relationship of total length-weight for the whole population, males and females were W=0.0029 L3.2954 (r2=0.91), W=0.0022 L3.3742 (r2 =0.89) and W=0.0052 L3.1409 (r2=0.93), respectively. T-test showed positive alometric (b>3) growth pattern for both sexes and the whole population.