Population dynamic of Anodonta cygnea in the Anzali wetland

Research on the Swan Mussel (Anodonta cygnea) population distribution and biometrics were conducted during 2015. Individuals sampling were carried out monthly from 14 stations. Length, width and height of shells was measured with using of a slide caliper to an accuracy and 0.01 mm and age of swan mussels were examined by counting annual growth on the shell surface. The highest and lowest frequency belonged to Bahambar station with 33% and Sheijan station with 8% respectively. The distribution of these shellfish is Central area and western parts of Anzali wetland. The age of shells was from 2 to 9 classes and 5 to 7 years old individuals dominated. The highest and lowest average of weight and length were calculated for Hendekhaleh station (W= 203.34 gr and L= 13.45 cm) and Bahambar station (W= 78.83 gr and L= 8.63 cm) respectively. Using Fisat ll program and based on Schiffre's method, L∞ = 13.65 cm and the growth coefficient factor 0.48 was calculated. The natural mortality coefficient was 1.154. Most recruitment (smaller in size) are observed in the months of September and early October. This indicates the existence of young reserves of reproduction and the addition of a new generation to the population. The existing reserves in Mahrooz to Bahmbar, which was the habitat of younger oysters, can be used for breeding programs of this species and preserving its stock.