Environmental Review Toolkit
Water, Wetlands, and Wildlife

Endangered Fat Pocketbook Mussel Gets Helping Hand in Arkansas

The round and inflated Fat Pocketbook Mussel, listed as endangered under the Endangered Species Act (ESA), is a recurring concern for many highway and development projects in the St. Francis River Basin in eastern Arkansas. However, recent efforts in the region may improve Fat Pocketbook Mussel populations. Since 2002, six Federal and state agencies and one university have been collaborating to develop and implement a plan for stabilizing and restoring the mussel's habitat. This plan will increase the number of reproducing populations and eventually lead to the delisting of species from the Federal Endangered Species List.

An SU doctoral candidate Andy Peck records Fat pocketbook data. Photo by Arkansas State University.
An SU doctoral candidate Andy Peck records Fat pocketbook data. Photo by Arkansas State University.

The project partners are the Federal Highway Administration (FHWA), the U.S. Fish and Wildlife Service (USFWS), the U.S. Army Corps of Engineers (USACE), the Arkansas Game and Fish Commission, the Arkansas Department of Environmental Quality, the Arkansas Highway and Transportation Department, and the Arkansas State University. Together, these partners are focusing their research on answering questions such as:

  • What is the historic range of the Fat Pocketbook Mussel? Where can scattered populations of the mussel still be found?
  • What does Fat Pocketbook Mussel habitat look like and can it be recreated?
  • Which of the formerly inhabited drainage areas is most suitable for mussel restoration?
  • Do different mussel species exhibit different movement patterns? How far does the Fat Pocketbook Mussel travel and what does does this mean for future projects?
  • What are the effects of bridge construction on the mussel, and how far downstream do those effects extend?
  • How have recent relocation efforts affected the Fat Pocketbook Mussel?
  • Do propagated juveniles grow at faster rates when reared in their natural habitat rather than in a laboratory setting?
  • Have propagation efforts been successful thus far? Are there ways to improve the process?
  • How do you guarantee genetic diversity and continued viable populations?
Arkansas State University researchers and U.S. Corps of Engineers personnel place juvenile fat pocketbook mussels in Stateline Ditch. Photo by Arkansas State University.
Arkansas State University researchers and U.S. Corps of Engineers personnel place juvenile fat pocketbook mussels in Stateline Ditch. Photo by Arkansas State University.

Although the research project is still underway, answers are beginning to emerge. These initial results will lead to a Habitat Restoration Plan and a USFWS Biological Opinion. As a result of research efforts, construction and maintenance crews will know more about how bridge construction impacts mussels downstream and the ways to deal with these impacts. The completed Biological Opinion will provide construction and maintenance crews with a protocol for highway projects that may impact the Fat Pocketbook Mussel. With these changes, the ESA Section 7 consultation process for projects will take 30 days instead of 210 days, an 86 percent reduction.

Historically, the Fat Pocketbook thrived in the St. Francis River drainage in northeastern Arkansas and in the Missouri "bootheel" floodway drainages in southeastern Missouri. Development-associated impacts have greatly diminished the numbers of this until now rather unknown mussel species.

AHTD biologist Josh Seagraves searches for fat pocketbook mussels in Stateline Ditch locations marked by yellow floats. Photo by Arkansas State University.
AHTD biologist Josh Seagraves searches for fat pocketbook mussels in Stateline Ditch locations marked by yellow floats. Photo by Arkansas State University.

Relatively high numbers of the Fat Pocketbook have been found in Stateline Ditch (a shallow tributary to the St. Francis River), so that has been selected as the site of Arkansas' relocation studies thus far. To test the adaptation of the mussels to a new environment, divers transferred mussels from one part of this drainage area to another and monitored their behavior. The divers also relocated mussels into the drainage area from drainage improvement projects elsewhere in the basin.

As for propagation, selected female mussels were taken to Missouri State University where they were put into laboratory tanks until the larvae, called glochidia, were harvested. The larvae were then put onto the host fish (the freshwater drum) in another tank. In about 10 days, when the larvae develop into juvenile mussels and drop off the fish host, the young mussels were collected and transferred to rearing facilities where they were allowed to grow from 6 weeks to 1 year. Following this growth period, the juveniles were transported to habitats such as Stateline Ditch for monitoring. One female mussel can produce thousands of juveniles, but only a few may survive to reproduce themselves.

If the program is successful, numerous Fat Pocketbook Mussels may eventually be translocated into the Tyronza River Basin in eastern Arkansas, once the research team determines its suitability. The Tyronza River flows into the St. Francis River and has been identified as a least altered reference stream for the Delta Ecoregion of the state by the Arkansas Pollution Control and Ecology Commission. That makes it a likely place for successful mussel restoration.

For more information please contact John Harris, john.harris@arkansashighways.com

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