Host length, age, diet, parasites and stable isotopes as predictors of yellow perch (Perca flavescensMitchill), trophic status in nutrient poor Canadian Shield lakes

Abstract

We used data from parasites and stable isotopes of yellow perch, Perca flavescens, to determine trophic status in four small Canadian Shield lakes as parasites allow the identification of both prey and non-prey dietary components in the host's community. Stable C isotope ratios for all perch ranged from ∼ −34 to −19‰ while stable N isotope ratios ranged from ∼4.5 to 12.5‰. These ranges are larger than those observed in many other fish species. Perch age was the most significant predictor of stable C isotope ratio and perch parasite fauna was the most significant predictor of stable N ratios. In particular, parasite fauna indicative of zooplanktivorous or piscivorous perch were most accurate for predicting fish trophic position and thus stable isotope ratio. Fish length and age showed fewer significant relationships with isotope ratios than parasite infracommunity or diet and suggests that trophic category for perch cannot always be predicted based on size.