Article content Measures taken to prevent the spread of the mussels have been largely successful in keeping them out of Alberta, and most pet store operators have been diligent in removing the moss balls from their inventories, he said. “(But) we are asking Albertans to take action to ensure zebra mussels are not inadvertently released into our environment,” said Nixon. Live zebra mussels were detected March 5 among a shipment of 2,000 moss balls at a Calgary pet shop distributor. They’re usually found on watercraft by provincial inspectors and by three dogs trained to detect invasive mussel species. The mussels have been found in Saskatchewan, B.C. and more than 20 U.S. states.