Because you have better things to do with your time than to spend it scraping mussels off of your boat and infrastructure.
The Quagga and Zebra mussels are causing enormous problems that are costing individuals time and money. Below are some pictures of the mess they are causing.
A shopping cart covered in zebra mussels caught the eye of a North Dakota man vacationing in Duluth, Minn., but he didn’t realize his plan to bring the unique junk back home was illegal.
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The Zebra Mussel shells in this photo are mostly 2 to 3 feet deep along the Green Bay shoreline on UW Green Bay’s Cofrin Arboretum. The empty shells accumulate in this way only in certain areas, apparently due to circulation patterns in the bay. It is not difficult to imagine that they have a strong direct influence on the ability of other animals and plants to live on these sites, in addition to their effect on the aquatic system when they are alive. <http://goo.gl/IgHp2>