Natural Resource Ecology and Management Publications Natural Resource Ecology and Management 6-2020 A comparison of Grass Carp population characteristics upstream and downstream of Lock and Dam 19 of the Upper Mississippi River Christopher J. Sullivan Iowa State University Michael J. Weber Iowa State University, [email protected] Clay L. Pierce U.S. Geological Survey, [email protected] Carlos A. Camacho Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/nrem_pubs Part of the Animal Sciences Commons, Ecology and Evolutionary Biology Commons, and the Natural Resources Management and Policy Commons The complete bibliographic information for this item can be found at https://lib.dr.iastate.edu/ nrem_pubs/338. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Natural Resource Ecology and Management at Iowa State University Digital Repository. It has been accepted for inclusion in Natural Resource Ecology and Management Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. A comparison of Grass Carp population characteristics upstream and downstream of Lock and Dam 19 of the Upper Mississippi River Abstract Grass Carp Ctenopharyngodon idella have been intentionally stocked for aquatic vegetation control across the Midwestern United States for several decades. During the 1970s, escapement of Grass Carp into the Missouri River facilitated their naturalization into much of the Mississippi River basin, including the Upper Mississippi River. Lock and Dam 19 (LD19) in Keokuk, Iowa, is a high-head dam that represents a focal point for naturalized Grass Carp management where populations may differ between upstream and downstream pools as result of limited upstream migration, but potential differences between populations have yet to be evaluated to the best of our knowledge. The objective of this study was to compare the relative abundance, size structure, condition, growth, and recruitment variability of Grass Carp collected upstream and downstream of LD19. We sampled Grass Carp monthly (April–October) during 2014 and 2015 from four locations in the Des Moines River (downstream of LD19) and five locations throughout the Skunk, Iowa, and Cedar rivers (upstream of LD19) using boat electrofishing and trammel net sets. We captured 29 Grass Carp upstream of LD19 compared with 179 individuals captured downstream. Trammel nets only captured Grass Carp downstream of LD19; trammel net catch per unit effort upstream of LD19 was low and ranged from 0.0 to 8.0 fish/net lift (mean 6 SE¼0.39 6 0.13). Electrofishing catch per unit effort ranged from 0.0 to 22.7 fish/h (1.49 6 0.30) and was higher downstream (2.42 6 0.30) of LD19 than upstream (0.57 6 0.07). Grass Carp downstream of LD19 tended to be smaller, younger, of lower body condition, had higher mortality rates, and were slower growing compared with those collected upstream and to populations documented in other systems. Understanding and monitoring adult Grass Carp population characteristics upstream and downstream of LD19 is necessary to determine how they may change in response to ongoing harvest efforts for invasive carps in these river reaches. Keywords Grass Carp, population characteristics, dam, Mississippi River, invasive Disciplines Animal Sciences | Ecology and Evolutionary Biology | Natural Resources Management and Policy Comments This article is published as Sullivan, Christopher J., Michael J. Weber, Clay L. Pierce, and Carlos A. Camacho. "A comparison of Grass Carp population characteristics upstream and downstream of Lock and Dam 19 of the Upper Mississippi River." Journal of Fish and Wildlife Management 11, no. 1 (2020): 99-111. doi:10.3996/062019-JFWM-046. This article is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/nrem_pubs/338 Articles A Comparison of Grass Carp Population Characteristics Upstream and Downstream of Lock and Dam 19 of the Upper Mississippi River Christopher J. Sullivan,* Michael J. Weber, Clay L. Pierce, Carlos A. Camacho C.J. Sullivan, M.J. Weber, C.A. Camacho Department of Natural Resource Ecology and Management, Iowa State University, 339 Science II, Ames, Iowa 50011 Present address of C.J. Sullivan: Department of Natural Resources and the Environment, University of Connecticut, 1376 Downloaded from http://meridian.allenpress.com/jfwm/article-pdf/11/1/99/2511819/i1944-687x-11-1-99.pdf by guest on 25 May 2021 Storrs Road, Storrs, Connecticut 06269 C.L. Pierce U.S. Geological Survey, Iowa Cooperative Fish and Wildlife Research Unit, Department of Natural Resource Ecology and Management, Iowa State University, 339 Science II, Ames, Iowa 50011 Abstract Grass Carp Ctenopharyngodon idella have been intentionally stocked for aquatic vegetation control across the Midwestern United States for several decades. During the 1970s, escapement of Grass Carp into the Missouri River facilitated their naturalization into much of the Mississippi River basin, including the Upper Mississippi River. Lock and Dam 19 (LD19) in Keokuk, Iowa, is a high-head dam that represents a focal point for naturalized Grass Carp management where populations may differ between upstream and downstream pools as result of limited upstream migration, but potential differences between populations have yet to be evaluated to the best of our knowledge. The objective of this study was to compare the relative abundance, size structure, condition, growth, and recruitment variability of Grass Carp collected upstream and downstream of LD19. We sampled Grass Carp monthly (April–October) during 2014 and 2015 from four locations in the Des Moines River (downstream of LD19) and five locations throughout the Skunk, Iowa, and Cedar rivers (upstream of LD19) using boat electrofishing and trammel net sets. We captured 29 Grass Carp upstream of LD19 compared with 179 individuals captured downstream. Trammel nets only captured Grass Carp downstream of LD19; trammel net catch per unit effort upstream of LD19 was low and ranged from 0.0 to 8.0 fish/net lift (mean 6 SE ¼ 0.39 6 0.13). Electrofishing catch per unit effort ranged from 0.0 to 22.7 fish/h (1.49 6 0.30) and was higher downstream (2.42 6 0.30) of LD19 than upstream (0.57 6 0.07). Grass Carp downstream of LD19 tended to be smaller, younger, of lower body condition, had higher mortality rates, and were slower growing compared with those collected upstream and to populations documented in other systems. Understanding and monitoring adult Grass Carp population characteristics upstream and downstream of LD19 is necessary to determine how they may change in response to ongoing harvest efforts for invasive carps in these river reaches. Keywords: Grass Carp; population characteristics; dam; Mississippi River; invasive Received: June 19, 2019; Accepted: December 19, 2019; Published Online Early: January 2020; Published: June 2020 Citation: Sullivan CJ, Weber MJ, Pierce CL, Camacho CA. 2020. A comparison of Grass Carp population characteristics upstream and downstream of Lock and Dam 19 of the Upper Mississippi River. Journal of Fish and Wildlife Management 11(1):99–111; e1944-687X. https://doi.org/10.3996/062019-JFWM-046 Copyright: All material appearing in the Journal of Fish and Wildlife Management is in the public domain and may be reproduced or copied without permission unless specifically noted with the copyright symbol &. Citation of the source, as given above, is requested. * Corresponding author: e-mail: [email protected] Journal of Fish and Wildlife Management | www.fwspubs.org June 2020 | Volume 11 | Issue 1 | 99 Grass Carp Population Characteristics C.J. Sullivan et al. Introduction and negative effects (e.g., Maceina et al. 1992) on invaded ecosystems. Native to the region between northern Vietnam and the Throughout the UMR, a series of 29 lock and dams Amur River basin in southern Siberia, Grass Carp Ctenophar- have been erected that regulate river discharge and form yngodon idella are now common throughout much of the a series of slow-moving pools that are more lentic than world (Cudmore and Mandrak 2004). Grass Carp ,200 mm the historical natural lotic discharge regime. Most in length typically feed on chironomidae larvae and larger notably, Lock and Dam 19 (LD19; Keokuk, Iowa) is a zooplankton (Cladocera and Copepoda; Opuszynski 1968; high-head dam that controls water levels at all flows, Watkins et al. 1981) but Grass Carp .270 mm in length are whereas most other UMR lock and dams (with the primarily herbivores, where micro- and macroflora material exception of Lock and Dam 1 near St. Paul, Minnesota) comprise the majority of diets (Michewicz et al. 1972; are tainter and roller gates or a series of tainter gates that Opuszynski 1972; Colle et al. 1978). Adult Grass Carp diets create a more free-flowing river when their gates are rarely deviate from plant material unless food resources open (Knights et al. 2002). Spillways at LD19 are unique become scarce (Bain 1993), which can significantly reduce in that they are elevated approximately 6 m above the aquatic plant biomass (Bettoli et al. 1993; Schramm and downstream river surface (Wilcox et al. 2004), creating a Downloaded from http://meridian.allenpress.com/jfwm/article-pdf/11/1/99/2511819/i1944-687x-11-1-99.pdf by guest on 25 May 2021 Brice 2000). Reductions of micro- and macroflora resulting semipermanent barrier, particularly