Survival, Growth, Food Selection, and Alimentary Canal Development of Intensively Reared Walleyes and Yellow Perch

Five genera of invertebrates, collected from a municipal sewage lagoon, were fed to newly hatched larval walleyes, (Stizostedion vitreun vitreun), and yellow perch, (Perca flavescens), to document survival, growth, food selection, and alimentary canal development of these fishes. Mean survival of walleyes for the 18 day period after hatching was 14.1%: mean unaccountable mortality was 43.5%. Forty-three percent of the walleyes remaining after 18 days survived an additional 32 days; mean unaccountable mortality was 33.8%. Mean daily length gain over the 50 day period was 0.8 mm/day. The cladoceran, Moina brachiate, was selected for by walleyes and yellow perch; the copepod, Cyclops vernalis, was initially ingested in the same proportion as fed, but later was selected for; the rotifer, Brachionus sp., was selected against by walleyes but was selected for by yellow perch during the first five days of feeding and was selected against thereafter; the cladocerans, Daphina magna and D. pulex, and the rotifer, Asplanchna sieboldi, were selected against by walleyes and yellow perch. Initially, significantly (P\u3c.05) more organisms were ingested by walleyes collected at 1100 than at 2300 hours; after day 12, more organisms were ingested by walleyes collected at 2300 than at 1100 hours, but there was a significant (P\u3c.05) interaction between the time of feeding and day of feeding, indicating that the effect of feeding time on the mean number of organisms was ingested by walleyes was dependent upon the day of feeding. Mean number of organisms ingested by yellow perch collected at 1100 hours was significantly (p\u3c.05) greater than the mean number ingested by yellow perch collected at 2300 hours. As the fishes grew they ingested progressively larger cladocerans indicating size and selection in feeding. The alimentary canal progressed through a series of changes as the larvae grew. The alimentary canal was completely developed in walleyes (22 mm, total length) by day 32 and was approaching full development in yellow perch (15mm, total length) by day 32. Invertebrates, collected from a municipal sewage lagoon, appeared to be of adequate size and species to feed walleyes and yellow perch during larval development