If You Are What You Eat, Can Fatty Acids Tell Us Your Diet Composition?

Accurate diet estimation of economically important fish species provides information on: potential contaminant sources, prey base changes, and recent habitat preferences. Macro-histological data carry well know impediments, thus work towards circumventing these shortcomings using biochemical methods has become popular. Mixing models have provided quantitative data for several taxa using stable isotope ratios; however, similar approaches have not been established with fatty acid profiles. To this end we illustrate experimental steps taken to develop and investigate the efficacy of a diet estimation model using fatty acid profiles with a freshwater predator. Feeding experiments, using natural prey, provide a framework for model development and testing. Our work herein was conducted using lake trout (Salvelinus namaycush) and yellow perch (Perca flavescens), native Great Lakes predators fraught with recruitment failures attributed to diets of non-native species. Obtaining a means to collect long term dietary preferences can provide clues into recurrent reproductive issues and changes in community assembly.