3.3.3 Risk to fish-eating humans
None of the fillets of rainbow trout or creek chub had a Hg concentration exceeding the US Environmental Protection Agency fish-tissue criterion of 300 ng/g wet weight for MeHg (Table 5). Concentrations in 31 of the 35 rainbow trout were less than 50 ng/g; no restrictions on fish consumption by humans are recommended by the Great Lakes Fish Advisory Workgroup (2007) for fish with concentrations less than 50 ng/g. Concentrations in the other 4 rainbow trout ranged from 51 to 69 ng/g, values in the lower end of the range (51–110 ng/g) for which the Workgroup recommended that fish consumption be limited to 2 meals per week. Concentrations in axial muscle of creek chub were higher than those in rainbow trout (Table 5), presumably due to differences in trophic position between these two species. The diet of creek chub often includes small prey fish, such as shiners, whereas rainbow trout are primarily invertivorous (Becker, 1983).