Fish Community Response to Hybrid Striped Bass Introduction in Small Warmwater Impoundments

Abstract

The popularity of hybrid striped bass Morone saxatilis × white bass M. chrysops as sport fish in large reservoirs has increased interest in using these fish to diversify small-impoundment fisheries. We examined the potential impacts that hybrid striped bass competition and predation could have on existing fish communities in farm ponds. Two sizes of hybrid striped bass (phase 2 mean weight = 42.9 g; phase 3 mean weight = 307.2 g) were stocked at a density of 62 fish/ha (40 phase 2 and 22 phase 3) into three ponds (2.4–6.5 ha). Hybrid striped bass diet analyses revealed that piscivory was seasonal and highly size-specific. More than 97% of fish prey recovered from stomachs were larval centrarchids (primarily sunfish Lepomis spp. and black crappies Pomoxis nigromaculatus) less than 15 mm in total length (<0.10 g). Using bioenergetics simulation, we estimated annual fish prey consumption by hybrid striped bass to be 96.9 kg/ha, equivalent to a minimum of 969,000 larval centrarchids (<0.10 g) per hectare. Hybrid striped bass may have reduced prey recruitment to the size preferred by largemouth bass Micropterus salmoides; largemouth bass relative weight (W_r) decreased significantly following stocking. Significant increases in total length and W_r of bluegills L. macrochirus, redear sunfish L. microlophus, and black crappies suggest that additional predatory pressure from hybrid striped bass enhanced sunfish size and quality and helped to alleviate black crappie overpopulation.