Some reproductive characteristics of swan mussel, Anodonta cygnea, in Anzali Wetland

Swan mussel, Anodonta cygnea, is a freshwater bivalve inhabitant of Anzali wetland, which population is in danger due to pollution and habitat destruction by human manipulation. In the present study, some reproductive traits of this species were evaluated for one year period using microscopic and biometric studies. The mean length was 10.6±0.1cm, the mean width was 6±0.04cm, the mean height was 4±0.04cm, the mean weight was 132±3g and the mean age was 6±0.1 years old. In all shells, two sexes were separated. There was no external feature for sex determination. The frequency of female was 1.5 times that of male. The mean diameter of mature oocyte and sperm were 139.95±8.1 and 4.5±0.26μm, respectively, and the mean area of ​​them was 15255.58±1834.4 and 9.1±1.16μm2, respectively. The mean fecundity was 107844.6±20621.9. Both of male and female gonads were in developing phase in spring (May and June) and in summer (July and August). The spawning stage occurred in the fall and the post-spawning stage in the winter. The development of glochidia were completed in January and the release of them from the gill were occurred between January and March.