Demographics of the Commercially Exploited Shovelnose Sturgeon Population in the Lower Wabash River, Illinois

Currently in the U.S., shovelnose sturgeon Scaphirhynchus platorynchus is the only commercially viable sturgeon species. In 2010, the U.S. Fish and Wildlife Service listed the shovelnose sturgeon as threatened in areas where it co-occurs with the endangered pallid sturgeon (Missouri and Mississippi Rivers); however, the population in Wabash River remains open to commercial exploitation. We assessed the population of shovelnose in the Wabash River for baseline demographic data to determine the impact of increased harvest. We sampled shovelnose sturgeon annually from 2000 through 2011 using various gears. Fish were tagged using PIT, Floy, and Monel tags to assess retention and population size. So far, more than 10,000 shovelnose sturgeons have been tagged of which more than 350 (~3.5%) have been recaptured. The tag retention rate was high for PIT (87.9%) and floy tags (83.53%) but significantly lower (c², p < 0.05) for Monel tags (54.3%). Analysis of recaptured individuals (which were at large for 200 to 3290 days) showed minimal to no growth in many of the larger individuals (> 650 mm). Our results infer the presence of a large population of shovelnose sturgeon in Wabash, but continued monitoring is necessary to determine the impact of increased fishing pressure.