Abstract
Research on the swan mussel population was conducted in 2005 on a sample of 497 individuals inhabiting Binowo and Bobolin Lakes, Szczecin, Poland. Length, width, height and age of individuals was examined. Binowo Lake was inhabited by individuals aged 1+ to 7+ years, while individuals aged 1+ to 6+ inhabit Bobolin Lake. Measurable features of swan mussels inhabiting Binowo Lake were as follows: individuals were 3.80 to 10.20 cm long, 1.70 to 5.70 cm wide, 0.70 to 3.70 cm thick, and in Bobolin Lake, 4.00 to 15.20 cm long, 2.20 to 7.70 cm wide, 0.80 to 5.70 cm thick. The age structure of both populations included individuals of diverse ages, with 3 and 4-year old individuals dominating in both lakes. A modest fraction of the youngest individuals (1, 2-year old) as well as the oldest (6, 7-year old) was observed in the examined lakes. All correlations between shell length, width, height and mussel age showed large positive correlations and results obtained from both lakes were similar.