Commentary: Once abundant throughout rivers in southern New Mexico and the Rio Grande basin in Texas and Mexico, the Texas hornshell, a freshwater mussel, has experienced a dramatic decline. Today, it is the only native mussel remaining in New Mexico and is scarce in Texas, occupying only 15% of its historical U.S. range. Habitat fragmentation and loss as a result of impoundments and reduced water quality and quantity are negatively impacting the Texas hornshell and other freshwater mussels across the Southwest.
After thoroughly reviewing the best available science, the U.S. Fish and Wildlife Service is proposing to protect the mussel as endangered under the Endangered Species Act (ESA). We are seeking comments from academia, the public, industry, local and federal agencies, states and other stakeholders.
“The Texas hornshell and other mussels across the Southwest are struggling because the waterways they call home are being altered and impacted by declining water quality and quantity,” said Dr. Benjamin N. Tuggle, the Service’s Southwest Regional Director. “Declining freshwater mussel populations are signs of an unhealthy aquatic system, which has negative implications for the fish, wildlife and communities that depend upon those rivers and streams.” “By working closely with private landowners, states and federal agencies we will improve water quality and quantity to benefit both the species and communities that rely upon those flowing waters.”
The Texas hornshell can grow to more than 4½ inches long and live up to 20 years. Like other freshwater mussels, it uses fish to complete its life cycle. Fertilized hornshell eggs develop into larvae and are released from the adults into the water where they are consumed by fish. The larvae then form parasitic cysts in the host fish’s gills, face or fins where they transform into the juvenile form and are released. If they are released in a suitable area, they can attach to a substrate and complete their development, becoming reproductive adult mussels.
In the Rio Grande, the Texas hornshell has been found downstream of Big Bend National Park and near Laredo in Webb County, Texas, in the Pecos River near Pandale, Texas, and the Devil’s River in Val Verde County, Texas. Historically, the Texas hornshell was widely distributed in Gulf Coast rivers in Mexico, however, its present status there is unclear.
The Service is currently working with partners in Texas and New Mexico on efforts to conserve the Texas hornshell. In New Mexico we are working with the state, Bureau of Land Management and industry along the Black River to develop a Candidate Conservation Agreement with Assurances (CCAA). Under the agreement, participating landowners and companies implementing conservation practices on behalf of the hornshell receive assurances that if the species is listed they will not face additional land management restrictions. The Service is also working with the New Mexico Department of Game and Fish to reintroduce the Texas hornshell into the Delaware River, an area within the historical range of the species.
In Texas, The Nature Conservancy and Texas Parks and Wildlife Department are managing their lands in the Devils River watershed to reduce sediment inputs and contaminants, thereby benefitting the Texas hornshell and other aquatic species. Research focused on helping improve the understanding of the species is being funded by the Office of the Texas Comptroller.
The Service is requesting comments or information from the public, other concerned governmental agencies, the scientific community, industry, or any other interested parties concerning this proposed rule. Comments must be received within 60 days, on or before October 11, 2016. You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter FWS–RX–ES–2016-0077, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”
(2) By hard copy: Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS–RX–ES–2016-0077; U.S. Fish & Wildlife Headquarters, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
America’s fish, wildlife, and plant resources belong to all of us, and ensuring the health of imperiled species is a shared responsibility. We’re working to actively engage conservation partners and the public in the search for improved and innovative ways to conserve and recover imperiled species.