San Joaquin River headwaters, © Jcookfisher

Road to Recovery: Birdwing Pearlymussel (Lemiox rimosus)

Defenders of Wildlife set the goal of moving more than 100 federally endangered species towards recovery over the next decade. Our “Road to Recovery” series highlights several of these plants and animals and outlines the challenges that lay ahead for improving their status.

Big or small, it’s important to protect them all. Freshwater mussels are among the most imperiled group of animals in North America, and the birdwing pearlymussel is no exception. This freshwater mussel is very small, reaching up to only 50 mm in length or about the size of a wine cork. As its name indicates, the shell and ribs of the birdwing pearlymussel resemble a wing-like design. Shells of juvenile mussels are often olive green, but become a blackish-brown color as they mature.

Birdwing pearlymussel, © Dick Biggins/USFWS

The birdwing once comfortably occupied 11 rivers in the Tennessee River system in Virginia and Tennessee, and one location in the Cumberland River in Tennessee. Unfortunately this unique and rare species of mussel now has anything but a comfortable life. Listed under the Endangered Species Act in 1976, the endangered mussel now occupies only slivers of the twelve waterways it historically inhabited. From 1992 through 2004, the U.S. Fish and Wildlife Service (FWS) reported that the species was in decline due to widespread pollution from coal mining, as well as water impoundments (water control structures like dams). But since then, FWS has started reporting the species as stable: a surprising outcome for an animal that FWS still categorizes as facing a high degree of threat and low recovery potential.

There are signs that the species is indeed improving. One milestone was the removal of the Columbia River Dam on the Duck River in Tennessee. This was the most immediate threat to the birdwing pearlymussel, and had been on track to eliminate the largest known population of the species, but removal of the dam improved the prospects for this imperiled mussel. More recently, oxygen injections into discharges from the Normandy Dam have improved water quality, and ongoing work to improve agricultural practices is doing the same. To maintain this positive trend, several crucial measures are needed. One of the most important steps is to continue advocating for the state environmental protection agencies and the U.S. Environmental Protection Agency to improve water quality. Here, some of the biggest gains could come from the Clean Water Act and its ability to limit water pollution. Another measure is to monitor and manage water withdrawals from the Clinch, Powell, Duck, and Elk rivers. If these threats are not managed, they could reverse many years of hard work and progress. Captive propagation and reintroduction is another strategy, but its long-term effectiveness is questionable if not paired with the more difficult task of conserving habitat.

It is in the hands of organizations such as Defenders of Wildlife, members of Congress, and the nation’s concerned citizens to show support for imperiled species such as the birdwing pearlymussel and stand up for our natural heritage before it is too late.

Want to know how you can help endangered wildlife across America? One way is to join our Conservation Crossroads campaign.

John Yeingst is Defenders’ Communications Coordinator

 

Post Your Comment

  • (will not be published)

You May also be interested in