title: Effects of prey assemblage on mercury bioaccumulation in a piscivorous sport fish.
abstract: Mercury (Hg) is a persistent global contaminant that biomagnifies, often reaching maximum levels in apex predators. Mercury contamination in piscivorous fish is a serious health risk for anglers and other fish consumers. We used data collected from a reservoir in Colorado to develop bioenergetics-based simulations of Hg bioaccumulation to estimate Hg concentrations in walleye (Sander vitreus), a popular sport fish. We evaluated how changes in the prey available to walleye might affect walleye Hg concentrations. Our simulations showed that such changes could result in almost a 10-fold range in walleye Hg concentration. Walleye consuming invertebrates had low growth, low growth efficiency, and high Hg concentrations. Conversely, when walleye diet contained only fish prey their growth and growth efficiency were higher and Hg concentrations were about 85% lower. These predictions were consistent with independent measurements in the study system observed under two different prey regimes in 2008 and 2013. Because prey assemblages in freshwaters can exhibit high natural and anthropogenic variability, understanding variation in predator Hg and providing accurate fish consumption advice to anglers and their families will require frequent monitoring of both predator and prey species. Further, manipulation of prey assemblages is a routine fishery management strategy that could be applied to reduce Hg contamination in piscivorous fishes.
authors.affiliation: Department of Fish, Wildlife and Conservation Biology, 1474 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1474, USA. Electronic address: brett.johnson@colostate.edu.
authors.forename: Brett M
authors.initials: BM
authors.lastname: Johnson
authors.affiliation: Colorado Division of Parks and Wildlife, Aquatic Research Section, 317 West Prospect Road, Fort Collins, CO 80526, USA. Electronic address: jesse.lepak@state.co.us.
authors.forename: Jesse M
authors.initials: JM
authors.lastname: Lepak
authors.affiliation: Department of Fish, Wildlife and Conservation Biology, 1474 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1474, USA. Electronic address: wolffba@gmail.com.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Wolff
mesh_terms: D000818:Animals; D003120:Colorado; D004032:Diet / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D005398:Fisheries / Q000706:statistics & numerical data; D005399:Fishes / Q000378:metabolism*; D020387:Food Chain; D005618:Fresh Water; D008628:Mercury / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Food web; Mercury mitigation; Prey contamination; Walleye