Jennifer Hogue; Advisor, Dr. Mark Pegg "Oxygen Consumption Rates for Bighead and Silver Carp in Relation to Life-Stage, Temperature and Activity Level" Bighead carp Hypophthalmythys nobilis and silver carp H. molitrix, collectively known as Asian carp, are fast-growing generalists, highly fecund, and are effective invaders of new ecosystems. Recently, their populations have exploded in the central rivers of the United States and are now spreading toward the Great Lakes. This range expansion has raised concern for groups that rely on the Great Lakes for their many natural resources. As part of a larger project in conjunction with the Illinois Natural History Survey, oxygen consumption rates (OCR) were measured using established respirometry methods for water temperatures (5, 10, 15, 20, and 25°C), life stages (juvenile fish < 50-cm, and adult fish >50-cm), and activity levels (0.3-m/s, and 0.6-m/s). Trials were conducted over a one hour period using a static respirometer to measure resting respiration rates and a swim chamber to conduct active trials. The relation between OCR and body mass for both species was allometric, with body mass being strongly correlated to OCR (r=0.92 (bighead carp), r=0.63 (silver carp)). The calculated b value, a coefficient used to correct mass related bias, for bighead carp was 0.7, while the calculated b value for silver carp was 0.76. Temperature significantly affected OCR in both species; while life-stage and activity level did not. Oxygen consumption rates did not differ between species (P<0.01). These results suggest that Asian carp have relatively high metabolic rates and the larger project serves to build a knowledge base allowing more accurate risk assessment for ecosystems that are now being threatened, or soon could be, around the world.