Analysis of growth and production of bluegill (Lepomis macrochirus) fry fed a natural versus artificial diet at the Fairport Iowa Fish Hatchery

In an aquaculture setting, bluegill (Lepomis macrochirus) are typically placed in earthen ponds to spawn and rely solely on zooplankton and other aquatic organisms for food. The aim of this study was to compare the number of bluegill fry produced and their growth when fed an artificial feed versus the traditional method. This study at the Fairport Fish Hatchery, Fairport, Iowa was the first attempt to determine if bluegill fry would adapt to and increase productivity with an artificial diet. The first goal was to determine if bluegill production could be increased in the experimental ponds through supplemental feedings. The second goal was to determine if bluegill could achieve a significantly larger size in experimental ponds compared to control ponds. Zooplankton abundance was examined to determine possible effects of artificial feeding on the natural food supply. Lastly, water quality parameters were examined relative to fry growth and production.;Eight ponds were chosen for this research and paired into experimental and control ponds based on similarity of acreage. Four ponds served as control ponds, the other four served as experimental ponds. Once fry were noticed in all ponds, fish in the experimental ponds received ;Water quality parameters of total ammonia nitrogen (TAN), nitrate, phosphorus, pH, and turbidity, were measured weekly. Dissolved oxygen and water temperature readings were determined daily; one at the water surface, and the other at the bottom of the pond. Zooplankton samples were collected weekly and the number of cladocerans, copepods, rotifers, and copepod nauplii were counted. Bluegill fry were sampled seven times throughout the study with a random sample of 50 fish from each pond. Fry length was measured in millimeters and a group of 10 from each sample were further examined for stomach analysis to determine when and if the bluegill actually consumed the feed. A random sample of fish was collected at harvest to determine weight per kg for each pond.;A paired t-test and a two sample t-test showed no difference in the growth rate between control and experimental ponds. All fish in experimental ponds did produce more fish at harvest than control ponds, but with the low sample size of four pairs of ponds this point could not be statistically proven.