Foraging specialization by the opportunistic largemouth bass (Micropterus salmoides)

Abstract

The opportunistic foraging nature of largemouth bass (Micropterus salmoides) is thought to preclude it from specialization when prey resources are in abundance. Here, we describe largemouth bass foraging specialization on Chaoborus spp. Chaoborus spp. specialization was unexpected because largemouth bass is a diurnal littoral visual predator, whereas Chaoborus spp. occupy the surface waters of the pelagic zone at night and are energetically unfavorable. Largemouth bass foraging in the pelagic zone, determined by core body temperature, had significantly (p50.001) more Chaoborus spp. per gut (249.3) than littoral foragers (68.4). Individual largemouth bass diet consistency over time was greater than the diet consistency of random pairings, indicating that pelagically oriented largemouth bass specialize in Chaoborus spp. predation. This unusual individual foraging behavior is likely caused by heavy intraspecific competition, which leads some fish to acquire new prey search images due to prey resource limitation. © 2011 Taylor & Francis.