Lake Michigan fisheries update
Brown Trout Stocking - Green Bay
In April, 93,000 brown trout yearlings were stocked offshore in Green Bay waters using the WDNR’s new research vessel for Lake Michigan, the RV Coregonus. This project is an attempt to revitalize the Green Bay brown trout fishery which has suffered low harvest for over a decade. The hope is that bringing fish offshore will move them away from nearshore fish and bird predators, and result in better survival. This should translate into increased catch and harvest by anglers of browns in the coming years.
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In May the WDNR used the Research Vessel Coregonus to conduct our portion of the spring Lake Michigan Lake-wide Assessment for lake trout and burbot. This assessment for the first time was conducted on the Northeast Reef (previous years targeted a variety of other areas). The survey captured over 300 lake trout and a half-dozen burbot for analysis. The data will be analyzed over the next few months but preliminary results were that the fish appeared in good condition and lake trout catch rates were slightly above the targeted goal. This lake-wide assessment is conducted by all the state, federal, and tribal agencies with management responsibilities on Lake Michigan and measures lake trout and burbot abundance, health, and diet.
Juvenile Chinook salmon were released from the WDNR’s Strawberry Creek Chinook facility near Sturgeon Bay during late May. These fish move downstream into Lake Michigan and will return to this site as adults in three to four years. Spring stocking is just one part of an annual cycle that includes fall egg collection and hatchery rearing that are needed to maintain the Chinook salmon fishery on Lake Michigan. Currently all of Wisconsin’s Lake Michigan Chinook salmon come from eggs collected at the Strawberry Creek facility making these efforts the cornerstone of Chinook salmon management.
Spring fyke net surveys of Rowley’s Bay in Door County targeting smallmouth bass were just completed last week. This three-week effort was part of an ongoing project to track abundance, size and age structure, and general condition of the smallmouth bass populations of Lake Michigan and Green Bay. Bass were captured, measured, other data collected, and then released back into the Bay. Data will be analyzed later this summer but at this time it is safe to say that the Rowley’s Bay smallmouth bass population has a good size structure and appears to be abundant.
Midges (Lake Flies)
Chironomids often known as ‘lake flies’ belong to the Diptera order which is made up of 1000s of morphologically different types of insects. In Lake Michigan, they form an important part of the benthic macro invertebrate population which many fish species utilize as food. The larval forms are often bright red in color. The adults drop eggs on or near the water. The egg mass sinks to the lake bottom, and may drift to deeper water where they develop into larvae. When they become a pupae, they swim up to the surface and emerge. The emergence of adults occurs in pulses throughout the summer in large swarms with peak production in late spring. The adults find their mate, produce eggs and eventually die. They have a short life span as adults. It is not uncommon to find these flies in the stomachs of trout and salmon in Lake Michigan especially in the spring.
Yellow Perch SCUBA survey
Our annual spring spawning assessment of Lake Michigan yellow perch was concluded this week. An unusually warm spring seemed to have accelerated the spawning this year as we observed that peak spawning occurred at least two weeks earlier than normal. Although the overall number of yellow perch caught was much lower than previous years, the general health and gonadal condition of perch appeared to be better than the previous two years. UW-Milwaukee researchers are looking into abnormalities in sex ratios and male condition.
A DNR dive team conducted an yellow perch egg deposition survey near the Green Can Reef just southeast of Milwaukee and assessed the density along transects set at index stations. The divers noted that the egg skeins were in an advance stage of development.