Early life history of fishes in restored and unrestored backwaters

River modifications have degraded backwaters, reducing critical habitat for larval fishes. Restoration projects, such as on the Illinois River's Swan Lake backwater, may be improving fish spawning and nursery areas. During 2004 and 2005, I (1) assessed restored and unrestored backwaters as fish nurseries by quantifying the density of larval fishes and their zooplankton prey and (2) investigated movement of larval fish between the river and Swan Lake by setting drift nets on a diel and seasonal basis.; A flood pulse occurred during June 2004, but not during 2005. When restored and unrestored backwater sites were compared to the Illinois River, families of fish changed between years, with fluvial-dependent taxa present during the flood pulse of 2004 and relatively absent during the drought of 2005. Higher fish densities and larger fish larvae were collected in backwaters as compared to the Illinois River during both years, probably due to abundant zooplankton and warmer temperatures. Larval drift was positively related to water velocity during 2004, and an estimated 32.3 million larvae drifted into Swan Lake. No other relationships between drift direction and abiotic variables occurred. In 2005, drift was related to larval density, probably due to the lack of a flood pulse.; Backwater-river connectivity in the Swan Lake HREP was preserved through the construction of water control stop-log structures, which allowed continual access by all fishes. The backwater management plans at Swan Lake enhanced habitat diversity and realized beneficial effects by creating a diverse and abundant age-0 fish community.