CHANNEL CATFISH SELECT FOR LARGER INVERTEBRATE PREY IN WESTERN SOUTH DAKOTA PRAIRIE STREAMS
Aquatic macroinvertebrates are important prey resources in freshwater ecosystems. Channel catfish (Ictalurus punctatus) consume invertebrates, but little is known about their prey size selectivity. Macroinvertebrates and catfish were collected from 23 river sites within the Grand, Moreau, Cheyenne, Bad, and White basins of western South Dakota. Chironomidae, Hydropsychidae, Leptohyphidae, and Simuliidae were the most common families in the 356 diets, and also the most abundant invertebrate prey items. In the environment they accounted for 32.6%, 30.4%, 3.0%, and 7.2% of available invertebrate prey, respectively. Percentages in the diet relative to total invertebrate prey were 51.5%, 11.9%, 5.9%, 21.4%, respectively. The size distribution represented by volume for individuals from these families was compared between the diets and environment among all sites. The frequency of larger prey sizes from all families was higher than expected based on proportions in the environment. This pattern was observed for Chironomidae and Hydropsychidae across all 5 river basins, but selection was more site-specific for Simuliidae and Leptohyphidae. Overall results suggest that channel catfish prey on disproportionately larger invertebrates than those available in their environment.
Erin Peterson (Primary Presenter/Author), South Dakota State University, firstname.lastname@example.org;
Stephen Jones ( Co-Presenter/Co-Author), South Dakota State University Department of Natural Resource Management, email@example.com;
Nels H. Troelstrup, Jr. ( Co-Presenter/Co-Author), South Dakota State University Department of Natural Resource Management, firstname.lastname@example.org;
Katie N. Bertrand ( Co-Presenter/Co-Author), South Dakota State University Department of Natural Resource Management, email@example.com;
Brian D.S. Graeb ( Co-Presenter/Co-Author), South Dakota State University Department of Natural Resource Management, firstname.lastname@example.org;