Center for Biological Diversity

For Immediate Release, February 8, 2018

Contact:  Michael Robinson, (575) 313-7017,

Vanishing Rio Grande Mussel Added to 'Endangered' List 

Texas Hornshell Barely Hangs On in New Mexico, Texas

LAREDO, Texas— After a 29-year delay, the U.S. Fish and Wildlife Service today protected the Texas hornshell, a species of mussel from the Rio Grande and its tributaries, as endangered under the Endangered Species Act. The last surviving native freshwater mussel in New Mexico, the hornshell is threatened by plans for a new dam, pollution and diminishing water in rivers due to global warming and agricultural and municipal use. 

“This unique mussel now has an excellent chance of survival in the face of would-be dam-builders and polluters, thanks to the Endangered Species Act,” said Michael Robinson at the Center for Biological Diversity. “This is good news for the hornshell and for all of us who rely on clean water and find solace and peace in rivers that still flow.”

The Texas hornshell is the 194th species to receive protection under the Endangered Species Act as a result of a landmark agreement between the Center and the Service to evaluate wildlife and plant species at risk. The Endangered Species Act has been tremendously successful, saving 99 percent of the animals and plants under its protection from extinction and putting hundreds on the road to recovery.

Five remaining populations of the Texas hornshell persist in the United States, in the Black River of southeastern New Mexico, the Pecos and Devil’s rivers in Texas, and two populations on the Lower Rio Grande.

While the mussel appears abundant in stretches of the Black River and Rio Grande, only three old, male mussels could recently be found in the Pecos River, with no females and no young located. A sixth population that had been reintroduced in the Delaware River in New Mexico may have been wiped out in August 2017 when 18,000 gallons of wastewater from oil and gas production along with 11 gallons of oil spilled into the river from a ruptured pipeline. The water is still too contaminated to safely allow surveys for the mussel.

In addition to the threat of pollution and diminishing water due to global warming and increasing human demands, the Texas hornshell is also imperiled by plans for a dam near Laredo, Texas. The mussels require flowing water in order to reproduce.

Texas hornshells typically occur in narrow areas of rivers and streams with sand, clay or gravel bottoms. They prefer undercut big boulders where the current slows, allowing the mussels to get a safe foothold and not be washed away in times of high water. They also anchor themselves in crevices and undercut riverbanks.

Male Texas hornshells release their sperm into river currents, and females downstream inhale them to fertilize their eggs. Embryos develop in specialized portions of the females’ gills, growing into sand-grain-sized creatures called “glochidia,” which are released into the current and attach themselves to fish gills. The glochidia grow to maturity and then drop to the bottom of the river.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.6 million members and online activists dedicated to the protection of endangered species and wild places.

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