Natural Resources, School of


First Advisor

Jamilynn B. Poletto

Date of this Version

Spring 4-24-2020


Horstman, Z. D. 2020. The effects of temperature on evacuation rates and absorption efficiency of Flathead Catfish. Master's thesis. University of Nebraska, Lincoln.


A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Jamilynn B. Poletto. Lincoln, Nebraska: May, 2020.

Copyright 2020 Zachary D. Horstman


Knowledge of fish gastric evacuation rates are a necessary component for both field and laboratory studies when trying to understand feeding rates, modeling energy budgets, and understanding trophic dynamics of aquatic ecosystems. Many freshwater fish encounter a broad range of environmental temperatures across life history stages, but the mechanistic link between temperature and physiological processes often remains poorly understood. We designed three recirculating aquatic systems capable of rearing Flathead Catfish Plyodictis olivaris in order to quantify gastric evacuation rates and gross energy absorption at three temperatures (17º C, 22º C and 25º C). We examined the relationship between temperature and its influences on consumption, gastric evacuation rates, and meal passage through the intestines of juvenile Flathead Catfish fed a single ration of food. We then used bomb calorimetry to examine the absorption efficiencies of juvenile Flathead Catfish by quantifying the proportion of calories remaining in dissected stomach and intestinal contents through time and by treatment. Temperature significantly affected consumption, gastric evacuation rates, and the amount of calories remaining in the intestinal contents of juvenile Flathead Catfish. Insight into the gastric evacuation rates of juvenile Flathead Catfish provides managers with a better understanding of consumption demands of these important top predators. Furthermore, our results begin to shed light on the bioenergetics of juvenile Flathead Catfish.

Advisor: Jamilynn B. Poletto