Scaphirhynchus Conference: Alabama, Pallid, and Shovelnose Sturgeon

St. Louis, Missouri, 11-13 January 2005

20.  EVALUATION OF THE CONDITION, DISTRIBUTION, STRUCTURE, AND GROWTH OF SHOVELNOSE STURGEON IN THE LOWER PLATTE RIVER, NEBRASKA

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

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

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

The objectives of this research are to evaluate the distribution, condition, size structure, and growth of the shovelnose sturgeon (Scaphirhynchus platorynchus) population in the lower Platte River, Nebraska.  Sturgeon were collected from four reaches near Two Rivers State Park, Elkhorn River confluence, Louisville, NE, and the Missouri River confluence.  Sturgeon were sampled using drifted gill and trammel nets, trotlines, and benthic trawls from March through October during 2000, 2001, and 2002.  Number captured, weight, and length were compared among reaches, months, and years.  The number captured showed no significant difference among years (p= 0.155), but a significant difference was detected among months (p= <0.001) and among sites (p= 0.016).  Incremental relative stock densities (RSD) were; stock-quality (1), quality-preferred (7), preferred-memorable (86), and memorable-trophy (6).   A significant difference was detected in RSD categories among reaches (p=<0.0001), months (p=<0.0001), and years (p=<0.0001).  Average relative weight (Wr) values for 641 sturgeon was 87, indicating a fit population.  Mean Wr showed no significant differences among years (p= 0.657), months (p= 0.698), and sites (p= 0.088).  Ages ranged from 5 to 14 years and 75 percent of the ages, where two or more readers agreed, were between the ages 7 and 9 with lengths ranging from 469 to 663 mm.  Shovelnose sturgeon in the lower Platte River appear to be healthy and exhibit increasing population densities in a downstream direction.