Date of this Version
The Prairie Naturalist 46:44–47; 2014
Widespread declines have been observed in numerous riverine fish species due to a host of anthropogenic related perturbations such as channelization, dam creation, and exploitation (Graham 1997, Gerken and Paukert 2009). Understanding life history and population demographics of riverine fishes is critical to their conservation. Specific to our study, the Mississippi River has undergone extensive habitat modifications that have changed the Upper Mississippi River (UMR) from a typical lotic large, free flowing river to multiple reservoir-like pools with reduced flow (LePage 1980, Hurley et al. 1987). These habitat transformations may impact sauger (Sander canadensis) populations within the Mississippi River. Several studies have documented sauger population declines due to similar factors in other systems such as the Yellowstone River (McMahon and Gardner 2001), Tennessee River (Pegg et al. 1996), Missouri River (Hesse 1994, McMahon and Gardner 2001) and in tributaries of the Great Lakes (Rawson and Scholl 1978). Dams may limit upstream migration to preferred spawning habitat (Nelson 1968, Pegg et al. 1997) or facilitate high exploitation (Pegg et al. 1996, Maceina et al. 1998) of sauger. Because of recent population declines observed across their range, sauger are globally listed as a species of concern (NatureServe 2013). However, in systems where native sauger populations persist, they remain an important recreational species (Maceina et al. 1998, Betolli et al. 2000, Pitlo et al. 2004, Meerbeek 2008, Meerbeek and Hoxmeier 2011) and top-level predator. Knowledge of population dynamics provides a basis for effective management and conservation of populations, but little is known about sauger dynamics within the lower portion of the UMR. Therefore, our objective was to quantify sauger recruitment, growth, and mortality within Pool 22 of the Upper Mississippi River.