MICHIGAN – The Michigan Department of Natural Resources has completed its annual Great Lakes survey season, conducted on all of our Great Lakes waters from April to November 2021. The data from these surveys directly informs fisheries management decisions and future actions on Great Lakes waters.
Survey highlights from the DNR’s Great Lakes fisheries research stations, as arranged from north to south, include:
Lake Superior and Northern Lake Michigan – Marquette Fisheries Research Station
The research vessel Lake Char, which surveys Lake Superior and focuses on lake trout, began work as soon as the ice was gone. The R/V Lake Char had a full season that included a trip to Isle Royale in June to document lake trout spawning in deep water and outside the expected fall spawning period, and the crew used a deep-water remotely operated vehicle that deployed video recording and a vacuum sampler. The sampling confirmed lake trout spawning in June and the deepest ever documented lake trout spawning in water over 300 feet deep. These surprising observations will be used with other survey data to further improve lake trout management in Lake Superior.
Lake Huron – Alpena Fisheries Research Station
The R/V Tanner and its crew from the Alpena Fisheries Research Station completed a full suite of fisheries assessments across Lake Huron during 2021, traveling from the Les Cheneaux Islands in the north to the Thumb Coast in the south, with many stops in between. Fieldwork began in April, with an annual lake trout survey that samples more than a dozen stations across the main basin through the month of May. The findings from the spring gill net survey continue to show strong natural reproduction of lake trout in the northern part of the lake, but declining recruitment of stocked lake trout in the south.
In early and mid-summer, the R/V Tanner and its crew conducted exploratory sampling and provided assistance to science partners including: remotely operated vehicle and water chemistry work at the Middle Island sinkhole, deploying of dissolved oxygen loggers in Saginaw Bay, and completing the second Outer Saginaw Bay hydroacoustics and midwater trawling survey in support of a multiagency evaluation to determine the success of recent cisco rehabilitation efforts.
By late August, the R/V Tanner again was deployed to Saginaw Bay for the annual September fish community survey. While data for the gill net portion of this survey are still being examined, preliminary results indicate the highest gill net catch rate for walleye since 1994, with yellow perch catch rates being similar to recent years. Of special note, two juvenile lake sturgeon stocked as part of recent restoration efforts in the Saginaw River watershed were captured and released.
Immediately after the conclusion of the Saginaw Bay survey, the R/V Tanner traveled north to the Les Cheneaux Islands, where an early October fish community survey revealed an increase in yellow perch gill net catch rates and a record smallmouth bass catch rate, which topped all previous data collected since 1969. The data collected throughout the entire 2021 survey season are being examined, shared with partners, and used to update models and decision tools that help inform fisheries managers on the status of lake trout, walleye, yellow perch and other important species across Lake Huron.