COLLEGE STATION — Researchers with the Texas A&M Institute of Renewable Natural Resources have found that relocating freshwater mussels may be an effective strategy for saving populations affected by drought or bridge construction.
Eric Tsakiris, research assistant, and Dr. Charles Randklev, research scientist, both with the College Station-based institute, have initiated a pilot project on mussel relocation in Texas. The project, which is the first to study the effectiveness of mussel relocation in the state, began with their relocation of three species of mussels in Central Texas.
Mussels from a site in the lower San Saba River were relocated to a site upstream with similar species and habitat. To date, all of the mussels recovered from the new site have survived and grown, Tsakiris said.
“Short-term relocation is successful,” he said, “but long-term, we still don’t know. Most studies suggest monitoring the mussels after relocation for a minimum of one to two years to get an idea of how they are performing.”
Although the early results are promising, the study was limited to three species and to the San Saba River, Randklev explained.
At the San Saba site, the research team collected 80 individual mussels in July 2012 and another 40 in Nov. 2012, then tagged the mussels so they could monitor their survival and growth. For the 80 relocated in July, Tsakiris said 88 percent were recovered and 100 percent of those survived.
Tsakiris, a graduate student in Texas A&M University System’s wildlife and fisheries science department, will continue to monitor the 120 mussels for two years as part of a broader dissertation research project.
“(The study) needs to be replicated in different places within Texas with different species to evaluate whether relocation is truly an effective management tool,” Tsakiris said.
Freshwater mussels are important to the state’s streams and rivers as indicators of stream health, Randklev noted.
“Declining populations of mussels can mean that a stream’s health is deteriorating,” he said.
Randklev said this pilot study was done in response to a contingency plan developed by the Texas Parks and Wildlife Department and U.S. Fish and Wildlife Service during the 2011 drought to explore conservation measures to alleviate potential impacts to mussels from the drought.
“The 2011 drought caused record-low flow levels in Texas streams, and many previously perennial streams went dry or became intermittent,” he said.
In addition to possibly being a mitigation tool during drought, he said, relocation may also be a viable option for the Texas Department of Transportation when working on bridges.
Because some freshwater mussels are state-threatened or candidates for listing under the federal Endangered Species Act, the department must evaluate a site for the presence or absence of these species prior to construction or renovations to bridges.
Tsakiris and Randklev, along with the Texas Department of Transportation, are also studying the feasibility of temporarily relocating mussels to other locations while the transportation department works on bridges in areas with mussel populations.
“There are a lot of questions about survival and mortality when relocating mussels,” Randklev said. “It is important to determine whether relocation is a viable option for drought or construction activities before any mussel species are formally listed.”
The Texas A&M Institute for Renewable Natural Resources is part of Texas A&M AgriLife Research, the Texas A&M AgriLife Extension Service, and the College of Agriculture and Life Sciences at Texas A&M University.