Guernsey

Spring trap netting targeting Bluegill and Black Crappie was conducted from May 1-3, 2024. Black Crappie and Bluegill are the primary management species at this time though recent sampling indicates substantial populations of Walleye and Northern Pike. Four similar spring trap net assessments have been completed prior to this one dating back to 2003. Catches of most of the measured species appear to be somewhat related to water temperatures at the time of sampling with the largest catches of Black Crappie found when water temperatures were in the upper 50sF while Bluegill preferred temperatures above 60F. Walleye and Northern Pike were most numerous during the earliest assessments when water temperatures were cooler. Water temperatures during the 2024 assessment were 52-53F. Spring trap nets have generally produced large samples of crappie ranging from 152 to 633 fish. The total catch in 2024 was 160 crappies ranging in size from 9.3 to 12.9 inches. Mean size was 10.7 inches and fish over 10 inches accounted for 82% of the sample. Comparisons to similar surveys show an increasing representation of crappies over 10 inches which comprised 34% of the catch in 2016 and 47% in 2018. Crappies over 12 inches have been absent or rare in all past surveys but made up 7.5% of the 2024 sample. Aging and length data have indicated that the presence of a heavily dominant 2010 year class has had considerable influence on the size of crappies in the lake for many years. Few small crappies were present. The 2024 trap netting captured just 9 Bluegills measuring from 7.2 to 8.2 inches in length. Bluegill have never been abundant in the spring trap nets with previous efforts netting from 36 to 108 fish. While the 2024 catch was the lowest on record it may have been a reflection of early season sampling dates and low water temperatures. Bluegills over 7 inches have typically constituted a high proportion of past samples and fish over 10 inches have been noted. Growth rates have not been evaluated but are likely pretty fast. The trap nets produced a catch of 29 Northern Pike with the largest fish measuring 37.6 inches. Mean size was 23.8 inches with 41% exceeding 24 inches. Pike samples sizes were smaller in 2016 (12 fish) and 2018 (8 fish) possibly due to warmer water temperatures. Large pike (35-37 inches) were also present in these past efforts. The 2024 sample of Walleye consisted of 16 fish between 13.1 and 24.7 inches. The size distribution was quite even with no length group especially prominent suggesting the presence of multiple year class. A total of 13 Largemouth Bass ranging from 13.1 to 18.2 inches were also captured and 11 of 13 fish exceeded 16 inches.

A standard lake survey was completed in May 2018 to obtain current information regarding the fishery. Trap nets were used in the shallows to assess panfish populations and gill nets were used in deeper, open water to assess Northern Pike, Walleye and Yellow Perch populations. Guernsey Lake is a small, quiet 125-acre lake located on the Sauk River about 7 miles southeast of Osakis. As a riverine lake, nutrient levels are high and water clarity is poor. Cattail is the dominant species of vegetation and essentially rings the entire basin. There is little to no residential shoreline development. A concrete public boat ramp is located on the southwest end of the lake near the inlet of the Sauk River. Species supported in the Sauk River can freely move in and out of Guernsey Lake. Black Crappie and Bluegill are the primary species of management, but there are Walleyes (natural not stocked) in the lake and Northern Pike approaching trophy size have historically been captured in survey nets. Black Crappies are abundant. Spring Trap netting regularly samples crappies over 10 inches in length. Since 2009, crappies have been getting bigger to the point where the 2010 year class is dominating the population. These fish measured 10-11 inches in 2018. Bluegills do not appear to be doing as well as crappies, however, the lake supports fish over nine inches, as evidenced in trap net sampling during the past decade. Northern Pike appear to be increasing in abundance. Past surveys found occasional pike in the upper 30 to low 40-inch range however, the 2018 survey did not find many large fish. A total of 33 Walleyes were sampled in gill nets, the largest was 25 inches. Because of Guernsey's riverine nature, large predators can move in and out with ease making their presence highly variable. The good news is that adequate prey-fish including Yellow Perch and White Sucker are common and appear to provide a sustainable forage base for large pike and Walleye. Anglers and dark house spearers are encouraged to practice selective harvest with Northern Pike and Bluegill. The sustained presence of large individuals of either of these species seems to be of particular importance in maintaining a quality, healthy fishery.

Guernsey Lake is a fertile, riverine lake. As part of the Sauk River, the lake is strongly influenced by the predominantly agricultural land use practices in the watershed. Severe algae blooms are common in summer, which negatively affects water clarity and vegetation growth. The secchi disk reading at the time of the summer survey was 2.9 feet. Cattail was the most common plant species found in the lake and formed a fringe around most of the basin. Very little in-lake vegetation was found, likely due to the poor water clarity. Low water levels can, at times, hinder boat accessiblity. Some shoreline fishing occurs along the mouth of the Sauk River at the boat access. A spring assessment was also conducted in early June of 2009 to evaluate the bluegill and black crappie populations. There are several fish species in Guernsey Lake that may attract anglers. While bluegill are probably the most popular species, there is an abundant northern pike population that could provide some excellent fishing. There was a wide range of sizes observed in the pike catches in both the summer survey and spring assessment. Average size of the pike in the summer survey at 24 inches or 3.6 pounds was better than most lakes in the area. Anglers also have a chance to see trophy size fish over 40 inches in length. The walleye population is sustained through natural reproduction so abundance may vary from year to year and anglers may have to work to find them. The largemouth bass population appears to be low according to spring electrofishing results, but all the bass caught were over 12 inches. A smallmouth bass was sampled for the first time by DNR gear in the spring assessment. Yellow perch numbers appear to be low which may be a result of the high northern pike numbers. Perch can be a principal prey species for both pike and walleye. An abundant white sucker population may, however, provide an alternative food source for the gamefish. Bluegill abundance may be down but some quality size fish are still present as most of the bluegill in the spring assessment were over 7 inches in length. Black crappie is one fish species that has adapted to turbid water. The species is probably the most abundant fish in Guernsey Lake as they were the most numerous species in both the spring and summer nets. Crappie reproduction has been excellent in 4 of the last 5 years and small fish as well as eating size are plentiful. There were, however, some crappie over 10 inches observed in the spring assessment. Carp are another species that has adapted well to turbid water and they appear to be very abundant in Guernsey Lake. Carp were caught in both the spring and summer nets and were also quite numerous in the electrofishing effort. Two species of bullhead, brown and yellow, were present in the lake although they are likely not abundant. Other species in the fish community include bowfin or dogfish, hybrid sunfish, and pumpkinseed. Anglers and spearers are encouraged to release the larger northern pike and walleye to minimize impacts on the fish community. Voluntarily limiting harvest of the large panfish will help sustain the quality and balance of the populations. A study of the water quality issues in Guernsey Lake has been initiated by the Sauk River Watershed District and MPCA.

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

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

Guernsey has a maximum depth of 19 feet and a mean depth of 7.4 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Guernsey is from 2018. Surveys this old should be treated with some caution — fish populations change over time.

Yes — Guernsey has confirmed zebra mussel. Clean, drain, and dry your equipment to avoid spreading invasives to other waters.