HALVERSON, K.L.*; PADILLA, D.K.; Whitworth College, Spokane, WA; Stony Brook University, NY: The Scoop on Fish Poop: Diet and Selectivity in the Molluscivorous Pile Perch.

Damalichthys vacca, the pile perch, is a common near-shore predator on molluscs, including the littorinid gastropod Lacuna, which is the most abundant gastropod in eelgrass beds in the Northern Puget Sound. We used fecal contents of 10 perch collected from an eelgrass bed to determine the local diet of D. vacca, and to test whether D. vacca was feeding selectively on the largest sizes of these snails, as has been shown in laboratory behavior experiments. Greater than 90% of fecal matter was composed of shell fragments, radulae and operculae of Lacuna vincta and L. variegata, suggesting that they were the dominant prey items. However, unlike laboratory experiments, we found no evidence for positive size selection by D. vacca when feeding on Lacuna in the field.