Mirror

A targeted survey of nearshore fish species in Mirror Lake was conducted on July 25th, 2022 by Index of Biological Integrity (IBI) Program Staff. Sampling sites were evenly spaced around the lake and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack electrofishing was completed at all ten sampling stations. Similarly, a 50-foot seine was used to sample three stations, a 15-foot seine was used at three stations, and soft sediments with abundant vegetation and deep water prevented the use of seines at four stations. Nearshore sampling captured 11species of fish including three species that are intolerant of disturbance (i.e., Blacknose Shiner, Rock Bass, and Smallmouth Bass) and zero species that are tolerant of disturbance. A concurrent summer trap net survey was conducted during the week of July 25th, 2022 by IBI Program Staff. Nine trap nets were set along the shoreline and in shallow offshore locations that encompassed multiple habitat types. Bluegill (85%) and Rock Bass (5%) comprised a majority of the trap net catch by number, and Bluegill (59%), Northern Pike (16%), and Largemouth Bass (10%) comprised a majority of the catch by biomass. The number of Bluegill and Rock Bass sampled per net were above the 50% quartile for similar Lake Class 20 lakes. The nearshore and trap net data were combined with gill net data from a June 2017 survey to describe the fish community and provide a Fish-based IBI (FIBI) score. The FIBI uses fish community data to measure a lake's health, and the types of fish species present can help identify any stressors that may be negatively affecting the lake environment. In Minnesota lakes, certain fish species cannot survive without clean water and a healthy habitat (e.g., Blackchin Shiner, Smallmouth Bass, and Rock Bass), while other species are tolerant of degraded conditions (e.g., Green Sunfish). The FIBI score, composed of several fish community diversity and composition metrics, indicates the overall health of a lake by comparing it to what is expected for a healthy lake. For additional information on the FIBI, search for "lake index of biological integrity" on the mndnr.gov website. Data from this survey indicates Mirror Lake is healthy as indicated by an exceptionally high FIBI score, well above the impairment threshold for aquatic life use determined for similar lakes. Data from this survey will contribute biological information about the health of the fish community to the Big Fork River Watershed assessment process in coordination with MN Pollution Control Agency.

Mirror Lake is in ecological lake class 20 and is located five miles west of Togo, MN within the Hudson Bay Watershed. The lake is 105 acres and has a maximum depth of 45 feet. A survey targeting nearshore fish species was conducted by Area staff on 3 July, 2017. Ten sampling sites (100 feet long) were evenly spaced around the lake shore, sampling a variety of habitat types. Each site is sampled by backpack electrofishing and seining with a 50-ft or 15-ft 1/8th inch mesh seine, depending on habitat condition. Shoreline seining was conducted at 9 sites; 5 using a 50-ft seine and 4 using a 15-ft seine. Backpack electrofishing was completed at all 10 sites. Nearshore sampling captured a total of 8 different species; 6 species by seining and 8 species by backpack electrofishing. The species can be found in the gear-specific catch tables in this report. Nearshore catches will be used with the gill net and trap net data from the standard survey conducted on 12 June, 2017, to calculate a fish-based Index of Biotic Integrity (IBI) score which is indicative of lake health. The surveys will assist the watershed assessment process in coordination with MN Pollution Control Agency.

Mirror Lake is a small 105 acre lake with 48 littoral acres and a maximum depth of 45 feet. Development along the 1.9 mile shoreline is mostly limited to the northeast. There are no inlets or outlets. Walleye are considered a primary management species with a management goal of maintaining a catch of 2.5/gill net. Though natural reproduction has been documented, Walleye fingerlings have been stocked at a rate of 0.5 pounds/littoral acre (25 pounds) every three years since 2009. Largemouth Bass are considered another primary management species with a goal of maintaining an electrofishing catch rate of 30/hour and with 40% longer than 12 inches. Northern Pike are considered a secondary management species. The fisheries lake management plan was last revised in 2007. The Walleye catch was within the expected range for lakes similar to Mirror Lake, yet lower than the previous survey and management goals. Lakes with similar habitat are not known to produce abundant Walleye fisheries. Lengths ranged from 10.5 to 20.5 inches, and were similar to the previous assessment. Age analysis indicated all the fish corresponded to a stocked year class. Largemouth Bass were sampled with electrofishing at a rate of 23/hr. The catch was lower than the management goal and the previous survey. A quality size structure was observed, meeting management goals. Lengths ranged from 5.3 to 17.9 inches with an average length of 11.9 inches and was similar to the previous survey. Scale analysis identified ages 2 to 9 and 11 present with growth similar to the statewide average. Largemouth Bass averaged almost 12 inches by age 5. Northern Pike were abundant, and sampled above the expected range in most surveys. Size structure was favorable and slightly better than past surveys. Lengths ranged from 11.0 to 35.8 inches with an average length of 22.7 inches. Age analysis identified ages 1 to 11 present. Growth was slow early but close to the statewide average by age 3. Northern Pike averaged 24.5 inches by age 6. Anglers are encouraged to release pike over 26 inches. Trap nets sampled Bluegill at a rate nearly triple the expected range, similar to past catches which have typically been abundant. Size structure has characteristically been poor, common for high density Bluegill populations. Scale analysis determined ages 3 to 10 and 12 were represented with growth similar to the lake class averages. Black Crappie gill net and trap net catches were comparable to lakes with similar habitats. Catches in past surveys tended to be variable. Size structure was favorable with lengths from 6.8 to 11.8 inches and an average length of 9.9 inches. Yellow Perch were the most numerous species caught in gill nets. The catch was almost double the expected range and the highest catch since 1979. Lengths ranged from 5.7 to 10.7 inches with an average length 7.2 inches. Other species sampled included Golden Shiner and Rock Bass.

Based on Minnesota DNR survey data, anglers target Northern Pike, Rock Bass, Walleye, Largemouth Bass, and Black Crappie in Mirror. See the full species list above for catch rates, size structure, and quality scores.

Minnesota DNR records list public access for Mirror. Check the DNR LakeFinder page for the launch type and directions before you go.

Mirror has a maximum depth of 45 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Mirror is from 2022.

No invasive species are on record for Mirror in Minnesota DNR data. Always clean, drain, and dry your equipment to help keep it that way.