Ontogenetic Diet Shifts of Blue Catfish and Flathead Catfish

Blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris) are native to the Mississippi River Basin and are primarily piscivorous as large adults but consume a variety of diet items as juveniles and young adults.  Traditional diet analyses are useful, but are often limited by temporal and spatial variation in diet, empty stomachs, lethal or intrusive techniques used to extract diets, and time investment required to quantify diets.  Here, we  use stable isotopes (δ¹³C and δ¹⁵N) to characterize the ontogenetic diet shifts in blue catfish and flathead catfish in the Mississippi River Basin. We collected and biopsied dorsal muscle tissue from blue catfish (200mm-1300mm) and flathead catfish (100mm- 1200mm) from pools 20, 21, 26 and open river conditions on the Mississippi River using tournament trails, commercial harvest and hoop nets. We dried and ground the muscle biopsies into a fine powder and will analyze for δ¹³C and δ¹⁵N stable isotope ratios using a mass spectrometer. Using size ranges from juvenile to adult, we will be able to determine the length diet shifts occur during the life of blue catfish and flathead catfish.