Journal of Fish Biology (2013) 82, 522–537 doi:10.1111/j.1095-8649.2012.03497.x, available online at wileyonlinelibrary.com Estimating diet in individual pumpkinseed sunfish Lepomis gibbosus using stomach contents, stable isotopes and parasites S. A. Locke*†, G. Bult´ e‡, M. R. Forbes‡ and D. J. Marcogliese* *Aquatic Biodiversity Section, Watershed Hydrology and Ecology Research Division, Water Science and Technology Directorate, Science and Technology Branch, Environment Canada, St. Lawrence Centre, 105 McGill Street, 7th floor, Montreal, QC, H2Y 2E7 Canada and ‡Department of Biology, Carleton University, 209 Nesbitt Biology Building, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6 Canada (Received 22 June 2012, Accepted 19 October 2012) The diets of 99 pumpkinseed sunfish Lepomis gibbosus from a pair of small, adjacent lakes in Ontario, Canada, were estimated from their stomach contents, trophically transmitted parasites and stable isotopes of carbon and nitrogen in fish tissue. The three methods provided virtually unrelated information. There was no significant correlation in the importance of any prey item across all three methods. Fish with similar diets according to one method of estimating diet showed no tendency to be similar according to other methods. Although there was limited variation in fish size and the spatial scale of the study was small, both fish size and spatial origin showed comparatively strong associations with diet data obtained with all three methods. These results suggest that a multidisciplinary approach that accounts for fish size and spatial origins is necessary to accurately characterize diets of individual fish.  2012 Her Majesty The Queen In Right of Canada Journal of Fish Biology  2012 The Fisheries Society of the British Isles Key words: carbon; gut contents; nitrogen; predator-prey; trophic ecology; trophically transmitted parasites. INTRODUCTION Fish diet is important to numerous aspects of aquatic ecosystems, ranging from the behavioural ecology of individual fishes to the structure of food webs. Three methods commonly used to characterize the diet of individual fishes are the exami- nation of stomach contents (Hyslop, 1980), the analysis of chemical isotopes in fish tissue (Michener & Kaufman, 2007) and the survey of trophically transmitted para- sites (Knudsen et al., 1996). Each technique has distinct advantages and limitations. Stomach contents often can be identified with relatively high taxonomic resolution, but provide only a snapshot that may differ from long-term diet. In addition, slowly digested prey may be overrepresented in stomach contents, and empty stomachs provide no information. In contrast, the ratios of stable isotopes of carbon (δ 13 C) and nitrogen (δ 15 N) in fish tissues reflect diet on a longer time scale. The identity †Author to whom correspondence should be addressed. Tel.: +1 514 496 6243; email: sean.locke@ec.gc.ca 522  2012 Her Majesty The Queen In Right of Canada Journal of Fish Biology  2012 The Fisheries Society of the British Isles