Comments: A small population, estimated at 7200 individuals, occupies the Canadian waters of the Lake St. Clair delta but is declining at a rate of 7% per year. Other Canadian populations (Ausable, Grand, Saugeen, sydenham Rivers) are very small with only 20 specimens collected from 148 sites in these rivers over the past 10 years. The population in the East Sydenham River consists of 18,900 individuals, but appears to be declining. The Upper Thames River population is estimated at 40,000 mussels, but may also be declining. The Maitland River supports the largest and healthiest Canadian populatin with CPUE 10 to 100 times higher than any other Canadian water body (COSEWIC, 2006).