Do littoral sampling schemes adequately represent largemouth bass diets?

Adequate characterization of diet composition is critical to understanding and managing largemouth bass (Micropterus salmoides) populations. The representativeness of sampling schemes within littoral zones is well studied but littoral oriented sampling schemes could still lead to inadequate characterization of diet composition through underrepresentation of pelagic foragers. We captured largemouth bass foraging in either the littoral or deep pelagic zones (metalimnion and shallow hypolimnion) of a small north temperate lake. Fish foraging in each respective zone was determined by angling depth and confirmed by body core temperature. Differences were evaluated between foraging zones in four metrics commonly applied in diet content analysis (percent by weight, percent frequency of occurrence, percent by number, and relative importance index). Prey characteristic of the pelagic zone, especially Chaoborus spp., were generally more important to fish captured in the pelagic zone than fish captured in the littoral zone. Prey characteristic of the littoral zone were generally more important to fish captured in the littoral zone than fish captured in the pelagic zone. However, there is considerable variability in these results and the diet contents of pelagic and littoral foraging largemouth bass are not significantly different from each other. Littoral largemouth bass sampling schemes may be robust to potential pelagic foraging but our study underscores the need for more precision when sampling using different diet metrics on populations with dichotomous foraging strategies.