Fern

Temperature and dissolved oxygen measurements were collected in the deepest basin in Fern Lake on August 7, 2024, 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. During the summer, 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 the profile from the deepest basin, the water temperature dropped below 8.8 degrees C (47.8 degrees F) at 23.3 feet, and the dissolved oxygen concentration decreased to 3.0 mg/L at 54.4 feet at the time of sampling. The thickness of this layer in the water column was 31.1 feet, indicating that oxythermal habitat was present for Lake Trout. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 5.9 degrees C (42.6 degrees F). 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. This is the first survey completed on Fern Lake during the late summer thermal stress period, however, data collected outside the thermal maximum period in 1980 and 1992 indicated suitable oxythermal habitat during that sampling period. The least favorable conditions were recorded in 1980 when the suitable habitat layer thickness was 30.4 feet. When inadequate oxythermal habitat is available, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Temperature and dissolved oxygen measurements were collected in the deepest basin in Fern Lake on August 7, 2024, 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. During the summer, 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 the profile from the deepest basin, the water temperature dropped below 8.8 degrees C (47.8 degrees F) at 23.3 feet, and the dissolved oxygen concentration decreased to 3.0 mg/L at 54.4 feet at the time of sampling. The thickness of this layer in the water column was 31.1 feet, indicating that oxythermal habitat was present for Lake Trout. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 5.9 degrees C (42.6 degrees F). 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. This is the first survey completed on Fern Lake during the late summer thermal stress period, however, data collected outside the thermal maximum period in 1980 and 1992 indicated suitable oxythermal habitat during that sampling period. The least favorable conditions were recorded in 1980 when the suitable habitat layer thickness was 30.4 feet. When inadequate oxythermal habitat is available, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

Temperature and dissolved oxygen measurements were collected in the deepest basin in Fern Lake on August 7, 2024, 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. During the summer, 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 the profile from the deepest basin, the water temperature dropped below 8.8 degrees C (47.8 degrees F) at 23.3 feet, and the dissolved oxygen concentration decreased to 3.0 mg/L at 54.4 feet at the time of sampling. The thickness of this layer in the water column was 31.1 feet, indicating that oxythermal habitat was present for Lake Trout. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 5.9 degrees C (42.6 degrees F). 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. This is the first survey completed on Fern Lake during the late summer thermal stress period, however, data collected outside the thermal maximum period in 1980 and 1992 indicated suitable oxythermal habitat during that sampling period. The least favorable conditions were recorded in 1980 when the suitable habitat layer thickness was 30.4 feet. When inadequate oxythermal habitat is available, Lake Trout are squeezed into unfavorable, warmer water conditions and experience higher levels of stress.

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

We don't have a confirmed public access point on record for Fern. Check the DNR LakeFinder page for current access details before you go.

Fern has a maximum depth of 65 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Fern is from 1992. Surveys this old should be treated with some caution — fish populations change over time.

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