Availability of Clupeid Prey to Primary Piscivores in Smith Mountain Lake, Virginia

Abstract Prey supply to predators is limited by the morphology, behavior, and spatial distributions of both predator and prey. To be eaten, prey must co‐occur spatially and temporally with the predator (distribution), the predator must recognize the prey as potential food and successfully capture it (behavior), and the predator must have a mouth large enough to ingest its target (morphology). We quantified the cumulative effect of these three factors on clupeid prey availability to both largemouth bass Micropterus salmoides and striped bass Morone saxatilis in Smith Mountain Lake, Virginia. As expected, morphological constraints were more severe for small predators. Alewives Alosa pseudoharengus were morphologically more available than gizzard shad Dorosoma cepedianum. Incongruent spatial distributions, the result of lake stratification, prevented striped bass from feeding on gizzard shad during summer and limited largemouth bass consumption of alewives. For unknown behavioral reasons, largemouth bass and striped bass consumed only clupeids between 40 and 160 mm total length. For largemouth bass, the available supply of alewives was equivalent to demand and that of gizzard shad exceeded consumption by 53%. For striped bass, the available supply of gizzard shad surpassed consumption by 26% and that of alewives was 4% greater than consumption. Annual consumption by all clupeid predators, including largemouth bass and smallmouth bass Micropterus dolomieu, striped bass, walleye Sander vitreus, flathead catfish Pylodictis olivaris, channel catfish Ictalurus punctatus, white catfish Ameiurus catus, and crappies Pomoxis spp., was 94% of the total available clupeid supply. Our analysis indicates that increased predation on the clupeid forage base of Smith Mountain Lake would lead to decreased prey production and produce prey shortages for piscivores that are dependent on this food resource.