Flat Horn

A targeted survey was completed in May 2024 consisting of spring trap netting to sample the adult Black Crappie and Bluegill populations. Both species are relatively new to the fish community of Flat Horn Lake with Bluegill first sampled in 2006 and Black Crappie first sampled in 2017. Populations of both species have been recorded in other waterbodies within the Little Isabella River watershed, indicating the fish could have migrated to the lake naturally. Spring trap netting successfully sampled the Black Crappie population with 39 individuals captured resulting in a catch rate of 2.17 per net. Crappie ranged from 4.9 to 12.6 inches long and were from 3 to 7 years old. The 2020-year class averaged 8.2 inches long at the time of the survey and accounted for 59% of the catch. Results of the survey indicate Black Crappie have established a naturally reproducing population with sufficient abundance to provide opportunities to catch and harvest fish. A sample of the Bluegill population was also collected with 43 individuals captured. More than 75% of the catch was less than six inches long and either age-3 or age-4. A smaller number of larger fish were also sampled indicating the lake contains sufficient habitat to support production of quality sized fish. Results indicate anglers currently have modest opportunities to catch and harvest Bluegill. Future monitoring will help determine the type of Bluegill angling opportunities the lake can sustain. While not targeted during the survey, Northern Pike were sampled in fair numbers and displayed good size structure. The average size of pike sampled was 23.5 inches long and 3.47 pounds with the largest fish measuring over 40 inches long. These results are not unexpected since the lake is known to produce big pike occasionally.

Flat Horn Lake is located 5.5 miles northwest of Isabella and is 52 acres in size with a maximum depth of 13 feet. There is a short carry-in access suitable for small boats and canoes at the US Forest Service picnic area and swimming beach at the end of USFS Road 182. The water has a brown, bog-stained color that limits visibility to about 4.5 feet in summer. The aquatic plant community has several submerged plant species with emergent and floating leaf plant beds distributed around the lake. Northern Pike, Walleye and Bluegill are the most common game fish species sampled in survey gear. A standard fisheries survey was conducted in July 2017 to monitor the status of the fish community and associated aquatic habitat. The Northern Pike catch was average relative to similar lakes in the Finland Area. The average size was 19 inches and 1.6 pounds with only 9% of the catch over 22 inches. Scale analysis indicated consistent recruitment to the population with seven year classes identified in the catch. Northern Pike growth was average compared to other lakes in the area. Historically, Walleye have been sampled in low numbers from Flat Horn Lake and the 2017 survey was no different. Survey nets captured just two adult Walleye that were over 16 inches long. This is consistent with previous surveys and suggests that natural reproduction has been able to maintain a small population of Walleye in the lake. Bluegill and Black Crappie lakes in the Finland Area tend to have small populations of fast growing fish that occasionally produce a strong year class. Spawning habitat in Flat Horn Lake is poor, and the cool climate of northeastern Minnesota may limit their production. Both species were captured at low numbers for the normal range for similar lakes. The 2017 survey was the second consecutive netting to sample Bluegill and was the first time Black Crappie were sampled in the lake. Bluegill size was decent with 63% of the catch greater than 8 inches and the largest fish measuring 8.9 inches and 0.7 pounds. Black Crappie were not particularly abundant and size was small with all fish from the same year class. Yellow Perch catch was below average for similar lakes and size structure was poor with the largest fish caught measuring 7.5 inches. Although not likely to be targeted by anglers, perch are an important forage species for the lake. White Sucker were sampled at average numbers compared to similar lakes and size averaged near 16 inches and 1.7 pounds. A single Largemouth Bass (8.1 inches) and a single young of the year bass were captured during the survey. Pumpkinseed and Rock Bass were also sampled in survey nets at low numbers. Small mesh trap nets designed to capture small bodied, non-game fish also sampled Common Shiner during the survey. Flat Horn Lake has a decent Northern Pike population with a fair number of nice pike. The Walleye population is small but when one is caught, they usually are decent size. The Bluegill and Black Crappie populations are still establishing in the lake and may be of interest to anglers in coming years. Flat Horn Lake offers a scenic setting for visitor to the lake and the 1.8 mile of hiking/cross country ski trail that circle the lake provide additional recreational opportunities

Flat Horn Lake is 7 miles northwest of Isabella in the Superior National Forest. The lake has a maximum depth of 7.5 feet and a Secchi disc is visible in the brown-stained water at that depth. There is a carry down access of approximately 100 feet suitable for canoes or small boats. There is a U.S. Forest Service maintained picnic area and a swimming beach and ski trail are adjacent to the access. The remainder of the shoreline is undeveloped and in a wild state. The fish community in Flat Horn Lake is comprised of northern pike, walleye, bluegill, rock bass, yellow perch and pumpkinseed sunfish. Largemouth bass were stocked in Flat Horn Lake in the 1980s however the species has not been sampled in netting gear and it is uncertain if they are present at this time. The lake is managed primarily for northern pike and no stocking is needed. In 2006 northern pike were sampled in average numbers as they have been in most of the assessments conducted on this lake. Mean size was 2.1 lb which is normal for the lake class and similar to the mean size in other assessments on this lake. Northern pike up to 29.3 inches were collected however most of the fish were smaller than 22 inches. Flat Horn Lake is not managed for walleyes. However, the species maintains a small population through natural reproduction. Walleyes were sampled in relatively low numbers in 2006, which is normal for this lake. Mean weight of walleyes collected in past assessments has been average for the lake class; however, mean weight increased in this assessment (2.3 pounds) and was above average. All the walleyes collected in this assessment were between 17 and 20 inches. Bluegills had not been sampled in Flat Horn Lake for over 20 years, but one was captured in 2006. In recent years bluegills have become fairly well established in adjoining Gegoka Lake, and may be expanding into Flat Horn Lake, though at this time it appears that bluegill numbers are low. Yellow perch were sampled in good numbers, including a few fish between 10-12 inches. However, most of the fish were smaller than 8 inches and probably too small to interest most anglers.

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

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

Flat Horn has a maximum depth of 13 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Flat Horn is from 2017. Surveys this old should be treated with some caution — fish populations change over time.

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