Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

55.  RELATIONSHIPS BETWEEN HABITAT AVAILABILITY AND RIVER DISCHARGE FOR SCAPHIRHYNCHUS STURGEONS IN THE LOWER PLATTE RIVER, NEBRASKA

James E Parham*, 311 Biochemistry Hall, School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, 68583-0759; Phone 402-472-2931; jparham2@unl.edu

Benjamin D. Swigle, 6935 Washburn Way, Klamath Falls Biological Field Station, USGS, Klamath Falls, OR, 97603; Phone 541-273-8689; bswigle@usgs.gov

Dane A. Shuman, 420 S. Garfield, Great Plains-Fish and Wildlife Management Assistance Office, US Fish and Wildlife Service, Pierre, SD 57501-5408; Phone 605-224-8693 ex. 33; dane_shuman@fws.gov

Vaughn A. Snook, Route 2 Box 85, Minnesota Department of Natural Resources, Lanesboro, MN, 55949, Phone 507-467-2442; vaughn.snook@dnr.state.mn.us

Edward J. Peters, 12 Plant Industry, School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, 68583-0814; Phone 402-472-6824; epeters2@unl.edu

Conservation of river sturgeon populations is a major concern for fisheries biologists in the Missouri River basin. The Platte River is the only remaining major tributary of the lower Missouri River that retains the naturally braided channel morphology once typical of North American Great Plains rivers. To aid in the development of appropriate conservation strategies for sturgeon, instream habitat was delineated and classified from aerial photographs of the lower Platte River. We classified 309 km of aerial images acquired on various dates in 1993, 1999, and 2002. Images were classified into one of five habitat types: exposed sandbars, shallow sandbar complexes, open water, woody islands, or no data. Contiguous images acquired on the same date were grouped together and resulted in 26 sections (mean 11.9 km) that covered 219,121,848 m2 of instream habitat. River discharge for the dates of the aerial images was determined from historical USGS gage data (range 0 to 595 m3/s). Strong relationships were found for the area of exposed sandbars (r2=0.89), shallow sandbar complexes (r2=0.87), and open water (r2=0.86) vs. discharge. The area of woody islands showed no relationship to discharge. Habitat use data for Scaphirhynchus albus (pallid sturgeon) and Scaphirhynchus platorhynchus (shovelnose sturgeon) gathered from radiotelemetry studies and drifted gill and trammel net collections were used to weight the available habitat categories. The habitat/discharge relationships were most accurately modeled by nonlinear equations where, in general, the quantity of suitable habitat changed more rapidly at lower river flows than at higher river flows. Results from this study will be used to assess current Platte River instream flow standards and to help promote the conservation of Platte/Missouri River sturgeon populations.