Food habits of the trout-perch, Percopsis omiscomaycus, in southern near-shore waters of Lake Michigan near Michigan City Indiana in 1973

Trout-perch, Percopsis omiscomaycus, were collected during the sample months June through September, 1973, in southern near-shore waters of Lake Michigan near Michigan City, Indiana. Three transects were sampled at depths of 1, 5 and 15 m using an otter trawl and a nylon bag seine. Fish were collected mainly at midnight because of diurnal migration and feeding demonstrated by trout-perch.Food habit analysis showed Chironomus spp. and Pontoporeia affinis to be the major food items of the trout-perch. Other organisms of lesser importance as food include: Eurycercus lamellatus, Eurytemora affinis, Chironomid pupae and alewife eggs, Alosa pseudoharengus.A combined monthly analysis of trout-perch food habits showed zooplankton and alewife eggs as important food items in, June decreasing.in importance throughout the remaining sample months. Amphipoda, primarily Pontoporeia affinis, was of greatest importance in June decreasing in percent volume in July and August and increasing in volume again during the September sample period. Chironomid larvae, primarily Chironomus spp., was a minor food source in June increasing to major proportions during the remaining sample months.Monthly food habits comparing size groups showed -greatest utilization of zooplankton as a food source by Group 1 (20 - 49 mm) trout-perch during the sample period June; decreasing as trout-perch size increased. There was a marked decrease in zooplankton consumption in the remaining sample months for combined size groups.Monthly food habits comparing size groups showed the greatest utilization of Amphipoda during the June sample month. Size Group III (100 - 139 mm) trout-perch consumed Amphipoda in largest quantities throughout the combined study period.Monthly food habits for Insecta consumption comparing size groups were at lowest volume in June, increasing in volume during the remaining sample months. Chironomus spp. was the major food item consumed by trout-perch.Ball State UniversityMuncie, IN 47306Thesis (M.S.)--Ball State University, 1977