7904 - Laserfiche WebLink

Home Browse Search

main channel because larger fish are less susse tible to predation by nonnative fish. These potential benefits could be offset, how er, if no ative fish species also experience enhanced growth and survivorship. In fact, so AW ive sp 'es may gain advantage because they are adapted to the lentil environment of the p ain wetland. Therefore, management and maintenance of these wetlands require considerable understanding of the community ecology of native and nonnative species and their interactions. Additionally, the enhanced productivity of floodplain wetlands may be important in enhancing survivorship of adult native fish. Modde (personal communication), Osmundson and Kaeding (1989), Tyus and Karp (1990, 1991), and Holden and Crist documented the use of floodplain wetlands or low velocity areas by adult razorback sucker. Wick (personal communication) speculated that adult fish use highly productive areas to replace valuable energy reserves exhausted while spawning. Resting habitats, therefore, may be important to enhance the survivorship of the adult population of razorback suckers in the Upper Basin. Levee Removal Issues The following paragraphs list primary issues concerning the floodplain habitat enhancement component of UCRBRIP. We have listed each issue either as a statement or a question. Each issue is followed by a brief discussion. The discussion of each issue is in the levee removal strategy. Naturallv Flooding Wetlands will be Used to Develop Management Criteria. To date, most of the effort on the benefits of floodplain function to endangered species within UBRIP has focused on "manipulated" sites that use human intervention to control flooding. A substantial amount of area floods naturally in the Colorado River system, yet little, if any attention, has been given to naturally flooding wetlands in the basin even though it appears that a substantial amount of flooding occurs in some areas during high flow years (e.g., 1983, 1984, 1995; Crowl, personal observation). This strategy added to information from previous studies allows managers to determine fish production dynamics in a range of natural floodplain wetlands and specific restorations (levee removal) sites as they become available. This document outlines a temporal and spatial strategy to compare fish population response and dynamics of 'restored' to that of natural floodplain areas. This plan contains a monitoring protocol designed to determine fish food (zooplankton, macroinvertebrate, etc.) and fish population responses (both native and nonnative) associated with these wetlands. Role of Manipulated Sites. Manipulated sites (i.e., Old Charlie, Walter/Walker, Johnson, Boat Bottom, etc.) will be used to address specific questions concerning floodplain function. Sites with control structures provide an opportunity to answer questions that cannot be addressed in existing natural wetlands, particularly as they relate to timing and duration of inundation. In addition, they also offer an opportunity to use the control structures to increase the effectiveness of fish sampling. They also allow the opportunity to determine the effectiveness of different gears in 5