Great Lakes Fish Monitoring and Surveillance Program

The Great Lakes Fish Monitoring and Surveillance Program was established in the late 1970s. This program helps EPA meet obligations under Section 118(c)(1)(B) of the Clean Water Act to establish a Great Lakes system-wide surveillance network to monitor the water quality of the Great Lakes with a specific emphasis on the monitoring of toxic pollutants. Project outcomes include an increased understanding of long-term contaminant trends in Great Lakes top predator fish.

Background and Objectives

Fish are exposed to chemicals in water and from the food they eat. Since these species occupy the highest trophic levels of the Great Lakes food web, contaminants can bioaccumulate and biomagnify in their tissues over time. The GLFSMP analyzes contaminants in whole top predator fish (Lake Trout and Walleye) to assess Great Lakes ecosystem health.

Monitoring Locations

Fish are collected for the GLFMSP from each Great Lake annually each fall on an even/odd year rotation. The triangles designate even year collection sites, and the circles designate odd year collection sites. Lake Trout are collected at every site except for Middle Bass Island, where Walleye are collected.

Similarly sized fish (measuring 600 mm – 700 mm in length) are collected to target fish of a similar age range for analysis, since older fish generally are exposed to more contaminants than younger fish. In the lab, fish aging techniques using maxillary bones and otoliths are used to verify age.

Data and Trends 

GLFMSP data can be accessed via the Great Lakes Environmental Database on the EPA Central Data Exchange. The graphic below shows PCB concentrations in Great Lakes Lake Trout and Walleye over time from each collection site since 1991. Concentrations of PCBs in Lake Trout and Walleye have declined over time at all GLFMSP collection sites.