MWC Eco-sweep: Upper Mississippi River Freshwater Mussel Pearl Industry

May 4, 2021

The Upper Mississippi River and tributaries house the greatest diversity of freshwater mussels in the world. Today, freshwater mussels are the most imperiled animal group in North America, a demise that does not get much public attention. In the following paragraphs, I will highlight a conservation effort underway to save one mussel species. In the meantime, enjoy this free guide to the Freshwater Mussels of the Upper Mississippi River: https://www.researchgate.net/profile/Stephen_Mcmurray2/publication/280298409_Freshwater_mussels_of_the_upper_Mississippi_River/links/55b0072e08ae11d31039ab6b/Freshwater-mussels-of-the-upper-Mississippi-River.pdf

In the early 1900s, freshwater mussels in the Upper Mississippi River were over exploited to the point of near extinction to make pearl buttons from their thick shells. When it was too difficult to find enough mussels to make pearl buttons, plastic buttons were invented to take their place. The following video describes how the mussels form mother of pearl and a slideshow of historic imagery related to the Upper Mississippi River Freshwater Pearl Industry.

Musseling the Upper Mississippi for pearls & buttons is no longer a widespread practice, but dams and other barriers limit host fish movement, keeping mussel populations from recovering at a sustainable pace. These endangered Higgins eye pearlymussels require walleye, smallmouth or largemouth bass to carry and disperse glochidia (baby mussels) upstream or downstream from their sedentary parents. As a result of impassible barriers, many mussel species went extinct in tributary rivers to the Mighty Mississippi. The Higgins eye in this photograph are part of an all-hands-on-deck conservation effort.

To help recover rare mussel species, scientists have been distributing mussels upstream of dams on small tributary rivers to the Mississippi. For example, female Higgins eye pearlymussels (endangered species) were collected from the Mississippi River near Cordova, Illinois. When the mussels were ready to release glochidia (baby mussels), they were placed in tubs with host fish (walleye, smallmouth or largemouth bass). The mussels squirt glochidia onto the fish, which attach to the fish’s gills and fins. The inoculated fish were released upstream of dams to see if new populations of mussels would establish where they had long been extinct. Due to the efforts of a committed team of scientists, surveys of the inoculated rivers have turned up young Higgins eye pearlymussels. https://www.fws.gov/midwest/endangered/clams/higginseye/higgins_fs.html