Lentic green sunfish populations in Nebraska Sandhill lakes

The green sunfish (Lepomis cyanellus) is common throughout Midwestern strea ms and rivers. However, relatively little is known about lentic populations . Our objective was to relate population characteristics of green sunfish t o the fish and invertebrate community as well as the physical and chemical habitat of natural lakes in the Nebraska Sandhills. Green sunfish were coll ected in 10 of 30 lakes sampled in 1998 and 1999 with trap nets. The number of stock (i.e., 8 cm) and longer green sunfish per trap net (catch-per-uni t-effort; CPUE) was variable, ranging from 0.2 to 1,429, but was positively related to yellow perch (Perca flavescens) CPUE. However, bluegill (Lepomi s macrochirus) and green sunfish CPUE were not related, likely because only five lakes contained both species. Green sunfish condition, indexed with r elative weight [Wr, stock to quality length (8-15 cm)], was positively rela ted to yellow perch Wr [stock to quality length (13-20 cm)]. Green sunfish CPUE was lower in lakes containing largemouth bass (Micropterus salmoides). Green sunfish Wr and size structure were inversely related to Bosmina sp. mean length. In addition, green sunfish condition and size structure were h igh in lakes with a low proportion of submersed vegetation. These relations hips suggest that high quality green sunfish populations coexisted with hig h quality yellow perch populations and are most likely to occur in lakes wi th low submersed vegetation coverage.