Eight mussel species have been delisted: the flat pigtoe, southern acornshell, stirrupshell, upland combshell, green-blossom pearly mussel, tubercled-blossom pearly mussel, turgid-blossom pearly mussel, and yellow-blossom pearly mussel. All of these mussels were previously found in the US Southeast, ranging from Mississippi and Alabama to Tennessee and Virginia—and in the case of the tubercled-blossom pearly mussel, as far north as Ohio, Michigan, and Illinois.  

What’s causing the decline of mussels in the US? According to the US Department of Agriculture (USDA), habitat loss is the number one threat. Dams, dredging, and channelization, as well as silting and contaminants, have likely contributed the most to the extinction of these species. 

Of the two delisted fish species, the first is the San Marcos gambusia, which was once found in Texas, in the headwaters of the San Marcos River. The other is the Scioto madtom, which was found in Ohio but hasn’t been spotted since 1957.