Taxonomic Utility of Fish Jaw Bones in Stomach Content Analysis and Rapid Development of Illustrated Identification Keys with Stacked Digital Images

Because piscivorous fishes are often economically important and information about their diets is useful to managers for developing accurate population models, there is a demand for high resolution diet data for these predators; however, the rapid breakdown of piscine prey items in digestion has long been an obstacle in stomach content analysis. Ossified skeletal components of fish are highly resistant to digestion relative to soft and connective tissues, but the usefulness of individual bones for distinguishing remains of one species from another is often limited. With the aim of increasing taxonomic resolution for piscine prey items in our feeding ecology studies, we investigated the utility of fish jaw bones in distinguishing fish taxa in stomach content samples by collecting live forage fish for evaluation. We used traditional methods of chemical digestion and staining to prepare bones for study, but found that we could increase our efficiency by replacing traditional line art with automated digital photography and image stacking software to produce high quality figures without depth of field limitations inherent to individual still photographs. Here we present preliminary data for a few common species to demonstrate the utility of our techniques.