The Michigan Department of Natural Resources surveys the diverse and important Great Lakes fisheries every year between April and November.
Crews from research stations in Marquette, Charlevoix, Alpena and Harrison Township gather data on fish populations, fish health and the presence and effects of invasive species. This information directly informs fisheries management decisions — such as stocking levels or regulated catch limits — and provides data on the success of past actions.
Surveying for 2025 has concluded, and DNR fisheries biologists are now synthesizing the findings and preparing for next year’s surveys. Interested in what the surveys found? Check out the highlights from each research station’s survey efforts below.
The crew of the research vessel Lake Char began work on Lake Superior as soon as the ice melted and continued through early November. The Marquette Fisheries Research Station is responsible for work that focuses on monitoring fisheries resources, including culturally and economically important species. These include lake trout, which were recently declared recovered in Lake Superior, lake whitefish and burbot. Surveys are conducted annually or at periodic intervals to track key population trends to monitor overall health of fishery resources.
Lake Superior
Data from the spring adult lake trout surveys on Lake Superior showed a slight increase in populations east of the Keweenaw Peninsula and slight declines west. The summer juvenile lake trout survey indicated slight declines in western and central areas (Ontonagon to Marquette) and slight increases in eastern waters (Munising to Grand Marais).
In June 2025, the RV Lake Char team surveyed Big Reef to assess lake trout populations. Big Reef is a popular lake trout sportfishing site, offshore about 30 miles north of Munising. A similar expedition to Klondike Reef was conducted in 2024 — to learn more about the crew’s roles, the fish sampling process and why this research is important for managing Michigan’s fisheries, watch the Klondike Reef expedition short documentary.
While out near Big Reef, the crew surveyed the deepest waters of Lake Superior (and all the Great Lakes) — about 1,320 feet — to assess siscowet lake trout populations. Siscowet lake trout is one of the lake trout morphotypes in Lake Superior that are most abundant in the deepest parts of the lake. They finished the survey season with lake trout spawning survey work between Marquette and Munising in late October and early November. During the 2025 field season, 198,000 feet (37.5 miles) of survey gill net was deployed for these surveys at 91 sampling stations across Lake Superior.
Northern Lake Michigan
Fisheries work in Upper Peninsula waters of Lake Michigan began shortly after ice-out with jaw tagging and acoustic transmitter tagging of walleye in Little Bay de Noc for movement studies of the species.
Fisheries assessment work in nearshore waters of lakes Michigan and Superior occurred during August and September. Crews sampled 20 locations (10 miles of trawling) in Lake Michigan’s Little Bay de Noc and Big Bay de Noc. Over 23,000 feet of survey gill net were deployed at 68 sampling stations spread across four locations in northern Lake Michigan (Big Bay de Noc, Little Bay de Noc, Naubinway and Manistique) and two locations in southern Lake Superior (Munising Bay and West Bay at Grand Marais). Catch data from these fall surveys allow researchers to assess changes in the fish community and populations of species such as walleye, yellow perch, smallmouth bass, northern pike, lake sturgeon and invasive Eurasian ruffe.
Interested mostly with the updates on whitefish and yellow perch please