Collaborators:

University of Michigan
US Geological Survey
University of Saskatchewan
Annis Water Resources Institute
Project Sponsor: University of Michigan Research and Development Grant

Publications:

Jude, D.J., Rediske, R.R. O'Keefe, J.P., Hensler, S., Giesy, J.P. 2010. PCB Concentrations in Walleyes and Their Prey from the Saginaw River, Lake Huron: A Comparison between 1990 and 2007. Journal of Great Lakes Research 36(2); 267-276. [more]

 

Project Summary:

Saginaw Bay and the Saginaw River are a designated Area of Concern by the International Joint Commission due to contamination of sediments with persistent inorganic and organic pollutants. This part of the Lake Huron watershed also is one of the more productive areas in the Great Lakes. Being the largest watershed in Michigan, the river and bay receive urban and agricultural runoff, as well as domestic sewage and industrial effluent. Sediments are contaminated with metals and anthropogenic compounds, such as PCBs, which has led to fish consumption advisories for this river for species such as channel catfish Ictalurus punctatus and common carp Cyprinus carpio and toxic effects in birds that feed on contaminated fish. Most toxicity has been attributed to several PCBs congeners. Similar contamination issues exist at other Great Lakes sites, with most restrictions on fish consumption due to relatively great levels of PCBs, even though concentrations of most contaminants have been declining and some advisories have been relaxed. Saginaw Bay hosts a world-class walleye Sander vitreus fishery and commercial fishers harvest large quantities of other important species. In efforts to rehabilitate this area, the Saginaw River mouth was dredged during 2000-2001 to remove accumulated toxic substances from the river mouth area. A subsequent Michigan Department of Environmental Quality sediment survey showed that concentrations of PCBs were less than the target level of 1 PCBs/kg. Concentrations of contaminants in forage fish and walleyes in this area were measured in 1990 as well as loadings to the river. These studies provide background data necessary to evaluate whether the dredging activity or other environmental processes, such as sedimentation, have caused a decline in concentrations of contaminants in the top predators walleye Sander vitreus and their forage fishes.

It was hypothesized that substantial contaminant loads are transferred from the sediments and zooplankton to gizzard shad (planktivores) and then to walleyes, which enter the river in fall-spring and spawn in spring. Furthermore, it was predicted that dredging and sedimentation of PCBs over time, if most of the PCBs are not coming from the tributaries, would reduce the amount of PCBs bioaccumulated in this food web. The objective of this study was to determine if dredging and environmental processes reduced concentrations of PCBs in walleyes and forage fish by comparing concentrations measured during this study with those in fish collected in 1990.