Gunflint

Temperature and dissolved oxygen measurements were collected from the deepest basin in Gunflint Lake on August 11th, 2025. This was done to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout, the most sensitive coldwater species present in this lake (Cisco, also known as 'Tullibee', are also present). Lake Trout require a layer of oxythermal habitat that contains water temperatures below 8.8 degrees C (47.8 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on data collected from the deepest basin (maximum sampled depth was 98.4 feet), the water temperature decreased to 8.8 degrees C (47.8 degrees F) at 40.5 feet and the dissolved oxygen concentration stayed greater than 3.0 mg/L for the entire sampled depth. This layer in the water column was 57.9 feet, indicating oxythermal habitat for Lake Trout was present. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was never reached because dissolved oxygen remained above 3.0 mg/L throughout the sampled depths. In this case, the minimum temperature, 6.0 degrees C (42.8 degrees F), was substituted as TDO3. TDO3 values cooler than 8.8 degrees C (47.8 degrees F) indicate that oxythermal conditions were suitable for Lake Trout at the time of the survey. Data collected by the Minnesota Department of Natural Resources during the period of maximum oxythermal stress (July 26th to Aug 24th) in 10 years, between 1976-2024, also indicated suitable oxythermal habitat in all years surveyed, with the least favorable conditions recorded in 2011 when the suitable oxythermal habitat layer was 23.3 feet thick. When adequate oxythermal habitat is not available, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Gunflint is a 4009 acre lake located 48 miles northwest of Grand Marais. A public boat landing can be found in the southwestern corner of the lake. Gunflint is primarily managed for lake trout and walleye. The 2023 survey of Gunflint Lake was the second of three surveys scheduled to evaluate the lake trout and walleye populations. Lake trout abundance was similar to historical catches and met the current management goal and is above average for similar area lakes. Lake trout ranged from 7.8 to 27.2 inches with a mean length of 18.5 inches. Aging results found 12 different naturally reproduced year classes with the oldest fish being 26 years old. Naturally reproducing lake trout populations are unique in Minnesota lakes, anglers targeting lake trout should consider catch and release practices with safe handling procedures. Walleye gill net catches were similar to recent surveys but fell slightly below average and did not meet the current management goal. Walleye ranged from 8.9 to 27.9 inches with a mean length of 16.1 inches. Aging results showed individuals from 9 different year classes present in the population. The largest year class (3-year-old fish) coincides with the walleye fingerling stocking of 2020. The oldest fish collected was 17 years old. Back calculated growth rates appear to be relatively fast compared to other area lakes, with walleyes reaching 17.2 inches at age 5. Some large sized walleye exist in Gunflint Lake. Northern pike catches were somewhat low but similar to surveys conducted since 2011. Northern pike were relatively large and ranged from 18.2 to 43.9 inches with a mean length of 25.1 inches. Gunflint Lake has the potential to produce trophy northern pike. The smallmouth bass catch is above average for similar area lakes, and in the normal range for Gunflint Lake. Smallmouth bass collected ranged from 8.8 to 17.8 inches with a mean length of 14.2 inches. Overall, good numbers of smallmouth bass with many large sized fish should be of interest to anglers. Rock bass numbers are relatively good in Gunflint Lake but have been slowly declining since their peak in 2011. Yellow perch catch rates were similar to historic levels. Rainbow smelt were first seen in Gunflint Lake in the 1970s. Catches in small-mesh gill nets designed to sample smelt have varied considerably in this lake but were considered low in 2023. Although smelt are an excellent source of forage, their naturalization has also been associated with reproductive failures among cisco, walleye, and lake trout. Catch rates of cisco were slightly above average for Gunflint Lake but comparable to surveys since 2003. Cook County, Minnesota lakes continue to be susceptible to aquatic invasive species introductions and Gunflint does have spiny water flea prevalent within the lake. Invasive species have the potential to significantly alter fish communities and overall lake health. Anglers should clean watercraft and fishing gear, drain all water, and dispose of unused bait in the trash to prevent accidental introductions.

Gunflint Lake is part of the headwaters of the Rainy River watershed. It is managed primarily for lake trout and walleye. Long range goals for lake trout are to maintain a minimum gill net catch (in deep and shallow sets combined) of 1.0 fish/set, with fish up to 25 inches in length present. Long range goals for walleye are to maintain a minimum gill net catch (in deep and shallow sets combined) of 4.0 fish/set, with at least 25% of that catch consisting of age-5 or older fish. This was the first of three surveys scheduled in the 2017 lake management plan (LMP) to determine whether population goals for walleye in this lake could be met under the current fingerling stocking program, without implementing any special regulations. Walleye stocking in Gunflint Lake resumed in 2008. Surveys done since that time (including this one) are part of the evaluation of that stocking. This was considered a targeted survey because we did not sample the Ontario side of the lake as we did prior to 2015. However, results should be at least roughly comparable to results of previous standard surveys (and directly comparable to the 2015 survey). The number of net sets, and the mix of deep and shallow sets, was similar to past surveys. The Gunflint Lake basin is relatively simple; it is essentially a long, deep, narrow trench. The border runs down the middle, and similar habitats can be found on both sides of the border. Gill net sets we were unable to make on the Ontario side of the lake were replaced by sets in similar habitat on the Minnesota side, to the extent we were able to make that determination. Lake trout are the primary management species in Gunflint Lake. They were fairly abundant in 2019, and of good size. The 2019 gill net catch met long range catch and size goals for the species from the 2017 LMP. The catch was typical for this lake historically, and fell well within the normal range for a Class 1 lake. Eleven year classes, all naturally produced, and including fish as old as 16 years, contributed to the catch. Although no strong year classes were observed, it did appear that lake trout reproduction continued at adequate levels. Growth of young lake trout had been about average for a lake of this type. Fish reached an average length of 12.3 inches by the end of their fourth year. Fair numbers of walleye were present in 2019, but they tended to be small. The combined catch of walleye in deep and shallow gill net sets (2.74 fish/set) fell short of the long range goal in the 2017 plan, but was similar to combined catches seen in this lake since 1986. The other aspect of the 2017 goal, that at least 25% of the walleye catch should consist of fish five years of age or older, was met in 2019; 16 of the 52 walleye sampled (31%) were five years old. However, no fish older than five were taken, so the quality of this population remained low. Stocked year classes (2014 and 2017) accounted for 89% of the 2019 walleye catch, indicating stocking was probably essential at this point for maintaining the walleye population in this lake. Walleye growth appeared to have been about average for the area; fish reached a mean length of 16.6 inches at the end of their fifth year, compared to an area average of 16.8 inches. Low numbers of older walleye have now been seen in 2011, 2015, and 2019. That problem (low quality, and low broodstock numbers) is not likely to be fixed by fingerling stocking alone. Although stocking seems to have maintained modest walleye numbers (at a fairly high cost), fish have been small and their survival to older ages has been low. As a result we have not yet been able to restore a high-quality walleye population to this lake. As has usually been the case in this lake, few northern pike were collected in 2019, but those that were seen were large. Of the six northern pike collected, four were over 30 inches in length (up to 35.1 inches). Five year classes (including fish up to eight years of age) contributed to the catch, although none were strong. Because of the small sample size, no strong statements could be made regarding northern pike growth. Growth of young fish appeared to have been about average for the area; at the end of their third year fish had reached a mean length of 21.1 inches. With a low population density, good access to cool waters, and smelt and cisco available as forage, this lake is capable of producing some trophy northern pike. The 2019 cisco catch in deep gill net sets fell within the normal range for that gear when used in Class 1 lakes in this area, and was similar to catches seen in Gunflint Lake since 2007. The combined catch in deep and shallow gill net sets was similar to catches seen in this lake since 1948, including those seen prior to the introduction of rainbow smelt. Cisco have provided important forage for walleye, lake trout, and northern pike in this lake, giving it the ability to support high-quality populations of all three species. Past surveys indicate that the cisco community in Gunflint Lake consists of northern cisco and shortjaw cisco, with the latter perhaps the more common of the two in this lake. Smallmouth bass were fairly abundant in 2019, and their average size was quite good. The smallmouth bass catch in shallow gill net sets was one of the higher catches seen in that gear in Gunflint Lake since 1983, and was high compared to similar lakes in the area. The mean weight for fish taken in those nets was also high, compared to similar lakes. Seven year classes contributed to the catch, with none standing out as exceptionally strong. Smallmouth bass growth had been average for the area; fish reached a mean length of 13.7 inches at the end of their seventh year. Rock bass numbers have greatly increased in Gunflint Lake since 2003, and the catch in 2019 remained high. The increase in rock bass numbers has been accompanied by a decline in yellow perch gill net catches, with 2019 being the first year in which no yellow perch were taken in gill net sets. Rock Bass probably compete with yellow perch and smallmouth bass in nearshore areas, and may have an adverse effect on both species. Their ability to provide forage for walleye and northern pike is unknown in this lake. Rainbow smelt were first seen in Gunflint Lake in the 1970s. Catches in small-mesh gill nets designed to sample smelt have varied considerably in this lake. Catches since 1994 have ranged from 2.0 to 62.3 fish/set, but have generally been under 12.0 fish/set. The 2019 catch was the lowest seen since 1994, and was well below the normal range (10.8 - 62.3 fish/set) for small-mesh gill net sets in lakes supporting smelt in this area. Although smelt are an excellent source of forage, they have also been associated with reproductive failures among cisco, walleye, and lake trout. Gunflint Lake is infested with spiny waterflea. Anglers and other users should be diligent about cleaning and drying any equipment used in this lake before moving to another.

Based on Minnesota DNR survey data, anglers target Lake Trout, Walleye, Northern Pike, Rock Bass, and Smallmouth Bass in Gunflint. See the full species list above for catch rates, size structure, and quality scores.

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

Gunflint has a maximum depth of 200 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Gunflint is from 2023.

Yes — Gunflint has confirmed spiny waterflea. Clean, drain, and dry your equipment to avoid spreading invasives to other waters.