If you still think that the zebra mussel is the most dangerous shellfish to invade our waterways, you haven’t been paying attention.
“Without question, the quagga mussel represents the greatest threat to the Great Lakes of any invasive species,” said Tom Nalepa, a research biologist with the National Oceanic and Atmospheric Administration.
“It took the quagga mussel longer to spread to all the lakes than the zebra, but once it got established, its populations exploded,” he added. “They are more abundant in shallow waters than zebra mussels ever were, and they are far more abundant in deeper water where zebra mussels were never found. They are much more efficient than zebra mussels and thoroughly outcompete them for nutrients.”
They’re also a huge concern in the West, where they have followed zebra mussels across the Rockies in bilges and livewells and attached to boat hulls and trailers. Here's a story about Utah.