| To predict the impact and potential spread of introduced exotic species, we must be able to quantify their dispersal capabilities and habitat requirements. Asian carp have become an increasing nuisance in recent years in the Illinois River, a tributary of the Mississippi River, potentially competing with native species. I implanted fifty silver carp and fifty bighead carp with ultrasonic transmitters during 2004 to quantify their macrohabitat use and their rate and extent of movement in the lower Illinois River (Rkm 130 to Rkm 0) during 2004 and 2005. Movement between Rkm 115 to Rkm 3 was continuously monitored with stationary receivers (N=9), and supplemented with intensive mobile tracking during the spawning season. Movement was associated with the rise and fall of river stage during the spawning season of both years. Mean km/day for bighead carp and silver carp was quantified for both species (bighead carp 6.8 km/day, silver carp 10.6 km/day), demonstrating that these species disperse widely. Available habitat was quantified to determine selection, and discriminant function analysis was used to describe microhabitat changes within macrohabitats between years. Both species preferred channel borders during low water periods, and island side channels during low and high water years. Both species were rarely found in water > 4 m, and avoided main channel habitat during low water. Bighead and silver carp also selected for specific abiotic factors within macrohabitat types during low and high water years, with silver carp showing more sensitivity to abiotic factors than bighead carp. Identifying habitat areas that both species prefer will facilitate management plans to target them for harvest, and determining characteristics of these preferred habitats will aid in predicting future establishment. |
