FAT POCKETBOOK

Potamilus capax

 

SPECIES CODE: F00T I01

 

STATUS:

On June 14, 1976, the fat pocketbook was designated as endangered throughout its entire range in Arkansas, Illinois, Indiana, Kentucky, Missouri, and Mississippi (USFWS 1976). A recovery plan addressing the fat pocketbook was approved November 14, 1989 (USFWS 1989).

 

SPECIES DESCRIPTION:

The fat pocketbook is a large (reaching approximately 130 mm in length) freshwater mussel with a shiny, tan or light brown shell without rays (USFWS 1989, INHS 1997).  Like other freshwater mussels, the fat pocketbook feeds by filtering food particles from the water column. The specific food habits of the species are unknown, but other juvenile and adult freshwater mussels have been documented to feed on detritus, diatoms, phytoplankton, and zooplankton (Churchill and Lewis 1924).  The diet of fat pocketbook glochidia, like other freshwater mussels, comprises water (until encysted on a fish host) and fish body fluids (once encysted).

 

REPRODUCTION AND DEVELOPMENT:

The reproductive cycle of the fat pocketbook is similar to that of other native freshwater mussels. Males release sperm into the water column; the sperm are then taken in by the females through their siphons during feeding and respiration.  The females retain the fertilized eggs in their gills until the larvae (glochidia) fully develop. The mussel glochidia are released into the water, and within a few days they must attach to the appropriate species of fish, which they parasitize for a short time while they develop into juvenile mussels.  Recent laboratory studies indicate that the freshwater drum (Aplodinotus grunniens) was the only suitable glochidial host of 28 fish species tested (Barnhart 1997).

 

RANGE AND POPULATION LEVEL:

The fat pocketbook was once widely distributed in the Mississippi River drainage from the confluence of the Minnesota and St. Croix rivers downstream to the White River system and was known in Minnesota, Wisconsin, Iowa, Illinois, Indiana, Missouri, Kentucky, and Arkansas (NatureServe 2003).  Most historic records for this species are from the upper Mississippi River (above St. Louis), the Wabash River in Indiana, and the St. Francis River in Arkansas (USFWS 1989).  The fat pocketbook is currently known to exist in approximately 200 miles of the St. Francis River system, including the Floodway and associated drainage ditches; the lower Wabash River, Indiana; the mouth of the Cumberland River, Kentucky; and the Mississippi River, Missouri (USFWS 1989).  The species also remains in the Ohio and White Rivers (NatureServe 2003). Over 2,000 individuals were transplanted from the St. Francis Floodway to the Mississippi River by the Missouri Department of Conservation in 1989 to augment that population in an effort to restore viability. Fresh dead shells have been collected from the Ohio River in Kentucky (USFWS 1989).  Populations appear to be stable in the lower Wabash and Ohio Rivers and the St. Francis River drainages as well as portions of the bootheel region in Missouri (NatureServe 2003).

 

HABITAT:

The fat pocketbook is a large river species which requires flowing water and stable substrate (USFWS 1989).  There is conflicting information in the literature regarding the fat pocketbook’s habitat preference.  Parmalee (1967) reported the fat pocketbook from sand and mud bottoms, in flowing water a few inches to more than eight feet in depth.  Individuals have also been found in sand, mud, and fine gravel substrates in the St. Francis River, Arkansas (Bates and Dennis 1983). Clarke (1985) reported this species primarily from sand substrates in the St. Francis River, Arkansas.  Jenkinson and Ahlstedt (1988) reported this species from the full range of habitat types, including shifting sand and flocculent mud, to hard clay and gravel. According to their findings, the most likely habitat is a mixture of sand, silt and clay (USFWS 1989).

 

PAST THREATS:

The greatest impact on the habitat of the fat pocketbook throughout its historic range has been from activities related to navigation and flood control. Channel maintenance dredging has been particularly destructive. The upper Mississippi River has been impounded for navigation and is dredged routinely to maintain a nine‑foot navigation channel. This species, once widespread in this river, has disappeared in recent years even from areas where other species (including the endangered species Lampsilis higginsi) continue to exist.  The presence of the fat pocketbook in dredged portions of the St. Francis Floodway indicates a recolonization of the channelized river reaches.  Dredging in the St. Francis basin has been primarily for the purpose of irrigation and flood control. Drastic changes in the watershed have resulted in loss of much of the original river channel and its associated mussel fauna. The occurrence of the fat pocketbook in the St. Francis River below the Marked Tree siphon is likely dependent upon the population in the St. Francis Floodway and the passage of glochidia‑infected fish through the siphons.  Bates and Dennis (1983) reported that much of the substrate of the White River, Arkansas, now consists of shifting sand bars. The only stable substrate left in these areas is found along the bank where some undredged mud ledges remain.  In addition, suspended silt, due primarily to erosion, appears to be increasing as mussel resources decline. This has been observed throughout the Mississippi River drainage (Ellis 1936, Thiel 1981).

 

CURRENT THREATS:

Channel maintenance activities and impoundments remain the greatest threats to the continued existence of this species (NatureServe 2003, USFWS 1989).  Other current threats to freshwater mussels are well documented in the general mussel description.

 

CONSERVATION MEASURES:

 

 

Exposure Scenario Summary Table  for the Fat pocketbook

 

Species

 

Life Stage

 

Habitat Type

 

Exposure Route

 

Diet

 

Significant Interspecies Relationships

 

fat pocketbook

 

glochidia

 

parasite

 

contact with water, diet

 

water (until encysted), fish body fluids (once encysted)

 

freshwater drum

 

juvenile / adult

 

sediment dweller

 

contact & ingestion of water, diet, sediment

 

filter feeder (bacteria, algae, detritus, sediment)

 

 

 

 

LITERATURE CITED:

 

Barnhart, M.C.  1997.  Reproduction and fish hosts of unionid species of concern.  Southwest Missouri State Univ., Springfield Dept. of Biology, Missouri Dept. of Conservation, Columbia, MO.

 

Bates, J.M. and S.D. Dennis. 1983. Mussel (Naiad) survey‑‑St. Francis, White, and Cache Rivers, Arkansas and Missouri. Final report.  Prepared for U.S Army Corps of Engineers, Memphis Dist.

DACW66‑78‑CO 147.  89 pp. Append. A‑E, 57 pp., 5 pls.

 

Churchill, E.P., Jr., and S.I. Lewis.  1924.  Food and feeding in freshwater mussels.  Bull. U.S. Bur. Fish. 39: 439-471.

 

Clarke, A.H. 1985. Mussel (Naiad) study; St. Francis and White Rivers; Cross, St. Francis, and Monroe Counties, Arkansas. Department of the Army, Memphis District, Corps of Engineers, Memphis, Tennessee (Order No. 84M 1666R). 28 pp. and appendices.

 

Ellis, M.M. 1936. Erosion silt as a factor in aquatic environments.  Ecology 17:29‑42.

 

Endangered Species Information Exchange. 1996  Species Id ESIS404004.  Virginia Tech Fish and Wildlife Information Exchange.  Available http://fwie.fw.vt.edu/WWW/esis/lists/e404004.htm.  (Accessed: December 10, 2003)

 

Illinois Natural History Survey.  1997.  Species Account, Potamilus capax (Green, 1832), Fat Pocketbook.  Illinois Department of Natural Resources.  Champaign, IL.  Available http://www.inhs.uiuc.edu/chf/pub/mussel_man/page128_9.html.  (Accessed: December 10, 2003).

 

Jenkinson, J.J. and S.A. Ahlstedt. 1988. A search for additional populations of Potamilus canax in the St. Francis and Cache River watersheds, Arkansas and Missouri. A report to the U.S. Army Corps of Engineers, Memphis TN. 104 pp. and appendices.

 

NatureServe. 2003. NatureServe Explorer: An online encyclopedia of life [web application]. Version 1.8. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. (Accessed: December 10, 2003 ).

 

Parmalee, P.W. 1967.  The freshwater mussels of Illinois.  III. State Mus., Popular Sci Series 8. 108 pp.

 

Thiel, Pamella A. 1981. A survey of Unionid mussels in the upper Mississippi River (Pools 3 through 11). Technical Bull. No. 124, Dept. of Nat. Resources, Madison, Wisconsin. 24 pp.

 

U.S. Fish and Wildlife Service. 1976. Endangered Status for 159 Taxa of Animals. Federal Register 41: 24062-24067.

 

U.S. Fish and Wildlife Service. 1989. A Recovery Plan for the Fat Pocketbook Pearly Mussel Potamilus capax (Green 1832). USFWS Region 4, Atlanta, GA.  22 pp.