Asian Carp Condition Factor (Wr) in the Mississippi River Basin: Geographic and Temporal Trends

Bighead carp and silver carp continue to be persistent invaders within the Mississippi River Basin (MRB). We currently lack a way to assess their condition throughout their geographic range in the United States. To monitor Asian carp condition locally and regionally through time, we have developed a standard weight equation (W_s) for each species using the RLP technique (50th percentile) throughout the MRB (bighead carp W_s: 2803 fishes, 37 populations from years 2000-2007 and silver carp W_s: 22,828 fishes, 106 populations from year 1999-2011). Mean relative weight (W_r) was compared for each river reach and population. Significant trends in silver carp condition over time were evident on the Illinois, Ohio and Missouri rivers showing a decrease in condition over time in the lower three Illinois River reaches, Ohio and lower Missouri River and an increase in the upper two Illinois River reaches, upper Ohio River and upper Missouri River. Pool 26 showed a significant decrease in bighead carp condition over time, but most other sites were highly variable. These equations will be a useful tool for biologists to assess Asian carp condition over time as management efforts continue throughout the MRB to expand on local and regional knowledge.