RESEARCH ARTICLE Integrated spatial health assessment of yellow perch (Perca flavescens) populations from the St. Lawrence River, Quebec, Canada) part A: physiological parameters and pathogen assessment Maeva Giraudo 1 & Audrey Bruneau 1 & Andrée D. Gendron 1 & Philippe Brodeur 2 & Martin Pilote 1 & David J. Marcogliese 1 & Christian Gagnon 1 & Magali Houde 1 Received: 24 December 2015 /Accepted: 27 May 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract A multi-disciplinary approach was used to evaluate the health of yellow perch (Perca flavescens) in the St. Lawrence River (Quebec, Canada), which is experiencing a severe population decline in the downstream portion of the river. Physiological parameters, liver alterations, trace metal concentrations, parasite prevalence and abundance, stable iso- tope composition, and the presence/absence of the viral hemorragic septicemia virus (VHSV) were evaluated in perch collected at six sites along the river: Lake St. François, Lake St. Louis (north and south), Beauregard Island, and Lake St. Pierre (north and south). Trace metal concentrations in surface water were higher in Lake St. Louis and downstream of a major urban wastewater treatment plant discharge, indicating that this effluent was a significant source of Cu, As, Ag, Zn, and Cd. Levels of Pb in surface water exceeded thresholds for the protection of aquatic life in Lake St. Louis and were neg- atively correlated with body condition index in this lake. In Lake St. Pierre, Cu, Ag, and Cd bioaccumulated significantly in perch liver and lower body condition index and greater liver damage were observed compared to upstream sites. Parasite analyses indicated a higher abundance of metacercariae of the trematodes Apophallus brevis and Diplostomum spp. in Lake St. Louis, and VHSV was not detected in the liver of yellow perch for all studied sites. Overall, results suggested that the global health of yellow perch from Lake St. Pierre is lower compared to upstream studied sites, which could contribute to the documented population collapse at this site. Keywords Yellow perch . St. Lawrence River . Trace metals . Health assessment . Pathogens Abbreviations BI Beauregard Island LLI Liver lesion index LSF Lake St. François LSL-N Lake St. Louis North LSL-S Lake St. Louis South LSP-N Lake St. Pierre North LSP-S Lake St. Pierre South PAH Polycyclic aromatic hydrocarbons PBDEs Polybrominated biphenyl ethers PCBs Polychlorinated biphenyls PFAS Perfluoroalkyl substances SLR St. Lawrence River VHSV Viral hemorragic septicemia virus WWTP Wastewater treatment plant Introduction The St. Lawrence River (SLR) is one of the largest waterways in North America, spanning over 3200 km from the Great Responsible editor: Thomas Braunbeck Electronic supplementary material The online version of this article (doi:10.1007/s11356-016-7002-9) contains supplementary material, which is available to authorized users. * Maeva Giraudo maeva.giraudo@gmail.com 1 Environment and Climate Change Canada, Aquatic Contaminants Research Division, Water Science and Technology Directorate, 105 McGill Street, Montreal, QC H2Y 2E7, Canada 2 Ministère des Forêts, de la Faune et des Parcs, Direction de la gestion de la faune de la Mauricie et du Centre-du-Québec, 100, rue Laviolette, bureau 207, Trois-Rivières, QC G9A 5S9, Canada Environ Sci Pollut Res DOI 10.1007/s11356-016-7002-9