Black Oak Lake is a small (119 acres), shallow (19 feet deep), natural environment lake. Prior to 2004 the lake had a low priority for management because of its small size and history of frequent winterkill. An initial survey was done in 1962 with a resurvey in 1985. Black Oak Lake last sustained a partial winterkill in 2001-02. A cooperative aeration agreement between the DNR and the Green Grove Rod and Gun Club first prevented winter kill during the winter of 2005-06, and led to the stocking of sunfish (in 2004 and 2006), black crappies and largemouth bass (2005), and walleye fingerlings (2008). Since 2006, aeration equipment has been used successfully to prevent winter kill.
In 2009, the northern pike catch rate (8.25/gill net) was greater than expected compared to lakes with similar characteristics. Average length and weight of northern pike was 23 inches and three pounds. Northern pike grew at a rate faster than statewide averages. Thirty percent of northern pike were larger than 24 inches. We have had some fantastic reports about northern pike spearing with fish over 30 inches.
Only one walleye (20 inches, age 3) was sampled by gill nets. In 2008, the Green Grove Rod and Gun Club received a permit to stock 2,200 walleye fingerlings. Those fish would be too small to be captured with gill nets in 2009.
Yellow perch (4.3/gill net) were captured for the first time at a rate within the range of expected values. Yellow perch are an important food item for northern pike, walleye, and largemouth bass.
Electrofishing for largemouth was accomplished on June 3, 2008 during daylight hours. Eleven largemouth were captured during one hour of energized-time. Largemouth bass ranged from 11 to 17 inches with an average length of 14 inches. The largemouth fishery is still improving since stocking occurred as recently as 2005.
Bluegill (39.5/trap net) were abundant and the catch was above the normal range. The average length of bluegill was six inches. Bluegill grew at a rate similar to lake class averages.
The catch rate of black crappie (33.0/trap net) was twice the normal range for the lake class. Black crappie were less than a harvestable size, however, with an average length of six inches. Growth of black crappie was below the lake class average across all age groups.
Considering the winter kill history of Black Oak Lake, black bullheads were not abundant. The five black bullheads ranged from 9-10 inches. Carp, golden shiner and hybrid sunfish were all present. These species are typical of lakes that experience winterkill.