Upper Midwest Environmental Sciences Center
Setting Quantitative Fish Management Targets for the Upper Mississippi River System
Sass, Greg and John Chick. 2017. Setting Quantitative Fish Management Targets for the Upper Mississippi River System. A completion report submitted to the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration Program from the U.S. Geological Survey, LTRM-2008APE2. 25 pages with 6 appendixes.
Fish population sustainability is of great importance to natural resource managers, yet is often difficult to evaluate due to a lack of long-term data to establish standards and a baseline fish community. A lack of standardized historic data, the unreliability of subjective recollections of previous fish population condition, and the difficulty of translating harvest and catch rates to relative abundance metrics further stresses the importance of long-term monitoring programs for objectively evaluating fisheries and setting management objectives. The U.S. Army Corps of Engineers’ Upper Mississippi River Restoration Program’s Long Term Resource Monitoring (LTRM) element on the Upper Mississippi River System (UMRS) (1989–present) is likely the premier fisheries dataset on large rivers in the world. We used daytime pulsed-DC electrofishing data from thirty-three fish species common to six regional trend areas (Pool 4, Pool 8, Pool 13, Pool 26, Open River, Mississippi River; La Grange Reach, Illinois River) from 1993–2007 to create “report card metrics” for evaluating species-specific relative abundances in relation to the overall UMRS (< 25th percentile = poor, 25th > 49th percentile = fair, 50th > 74th percentile = good, ≥75th percentile = excellent). We also used total fish catches from LTRM data in 1993–2002 to develop percentile standards for fish species diversity using the Shannon-Wiener diversity index (H’). Lastly, we ranked each regional trend area based upon relative species abundance and species diversity to provide management recommendations for improving fisheries. The thirty-three fish species common to each regional trend area included sportfishes, ancient fishes, commercial fishes, forage fishes, and non-game fishes. Standards for UMRS relative abundances were variable and species-specific. Gizzard shad (Dorosoma cepedianum) showed the highest relative abundances, while mooneye (Hiodon tergisus) had the lowest relative abundances. Fish species diversity was relatively low and highly uneven across the entire UMRS (H’ = 0.7 – 3.11) as a consequence of high total catches of bluegill (Lepomis macrochirus), common carp, emerald shiner (Notropis atherinoides), and gizzard shad. Based on our relative abundance standards, the regional trend areas ranked from best to worst were: 1) Pool 13 (Mississippi River); 2) Pool 26 (Mississippi River); 3) Pool 8 (Mississippi River); 4) La Grange Reach (Illinois River); 5) Pool 4 (Mississippi River); and 6) Open River reach (Mississippi River). Regional trend area rankings from best to worst for fish species diversity were: 1) Pool 8; 2) Pool 13; 3) Pool 26; 4) Open River; 5) La Grange; and 6) Pool 4. Our results suggest that management efforts to improve fisheries and habitat should be prioritized towards Pool 4 and the Open River Reach of the Mississippi River, as well as, the La Grange Reach of the Illinois River. Although our standards were arbitrarily chosen using empirical data, we encourage resource managers to tailor our recommendations to suit state and federal fisheries management needs or beliefs. Our methodology and ability to create standards to objectively assess fish population and community status should serve as an evaluation tool to measure the health of the UMRS fisheries in the future. We also suggest that our standards be updated periodically (e.g. every 3–5 years) to create a new baseline, upon which, further improvements to the UMRS fishery may be gauged.