Linking Bluegill and Gizzard Shad Prey Assemblages to Growth of Age-0 Largemouth Bass in Reservoirs

Abstract
Either gizzard shad Dorosoma cepedianum or bluegills Lepomis macrochirus dominate prey assemblages in many small (<100 ha) Ohio reservoirs. Because gizzard shad spawn early in the spring and their offspring grow rapidly, age-0 gizzard shad may be invulnerable to age-0 largemouth bass Micropterus salmoides thereby compromising this piscivore's growth and, potentially, recruitment. To test this hypothesis, we quantified growth, abundance, and diets of age-0 largemouth bass in reservoirs dominated by age-0 bluegills (one reservoir) or age-0 gizzard shad (two reservoirs) during June through early October 1992–1994. In the bluegill-dominated reservoir, age-0 largemouth bass grew slowly (about 0.04 g/d) during June through mid-August. Though age-0 bluegills became abundant after mid-August, contributing to rapid growth (about 0.2 g/d) of age-0 largemouth bass, these age-0 largemouth bass only reached small to moderate sizes by fall (range of mean wet weights, 3–7 g). In the reservoirs dominated by gizz...