9781934874189-ch19

Case Studies in Fisheries Conservation and Management: Applied Critical Thinking and Problem Solving

Case 19: Size-Structure Assessment for Pallid Sturgeon

doi: https://doi.org/10.47886/9781934874189.ch19

The pallid sturgeon (Figure 19.1) is a rare fish that is endemic to the Missouri River and the lower half of the Mississippi River. Your challenge for this case study will be to assess size-structure data for three pallid sturgeon population samples.

The pallid sturgeon was formally listed as an endangered species in 1990 (U.S. Fish and Wildlife Service 1990), which prompted various recovery and management actions by biologists, researchers, and resource managers at federal, state, and university levels (U.S. Fish and Wildlife Service 1993). These actions included population augmentation, biological monitoring, and detailed life history research.

The study area included in this case study encompasses the Missouri River from Montana through Nebraska. Six mainstem dams were constructed on the the upper Missouri River (Figure 19.2). These dams blocked movements and perhaps migrations of pallid sturgeon, and may have contributed to their population declines.

See Table 19.1 for the length-frequency information obtained by trammel netting for three pallid sturgeon samples at three locations along the Missouri River. First, plot a length-frequency histogram for each of the three samples. Next, calculate the proportional size distribution (PSD; Guy et al. 2007) value for each sample (at the least, calculate PSD, PSD-P, PSD-M, and PSD-T). If you need the equations to calculate these indices, see Anderson and Neumann (1996) or Neumann et al. (in press). Stock, quality, preferred, memorable, and trophy lengths for pallid sturgeon are 33, 63, 84, 104, and 127 cm (fork length).