Bluewater

A targeted survey of nearshore fish species in Bluewater Lake was conducted beginning on July 16th, 2024 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 seven stations, a 15-foot seine was used at two stations, and site conditions prevented the use of seines at one station. Nearshore sampling captured 17 species of fish including eight species that are intolerant of disturbance (i.e., Banded Killifish, Iowa Darter, Least Darter, Mimic Shiner, Northern Sunfish, Pugnose Shiner, Rock Bass, and Smallmouth Bass) and one that is tolerant of disturbance (i.e., Green Sunfish). A concurrent summer trap net survey was conducted beginning on July 16th, 2024 by IBI Program Staff. Nine trap nets were set along the shoreline and in shallow offshore locations that encompassed multiple habitat types. Bluegill and Hybrid Sunfish comprised a majority of the trap net catch by number and biomass. The number of Bluegill and Black Crappie sampled per net was below the 50% quartile for similar Lake Class 23 lakes. Conversely, the mean weight of Black Crappie sampled per net was above the 50% quartile for Lake Class 23 lakes. The nearshore and trap net data were combined with gill net data from an August 2022 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., Mimic Shiner, Northern Sunfish, and Pugnose Shiner), while other species are tolerant of degraded conditions (e.g., Black Bullhead, Fathead Minnow, and 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. An additional survey was completed on Bluewater Lake in July 2015 resulting in a high, but similar FIBI score. For additional information on the FIBI, search for "lake index of biological integrity" on the mndnr.gov website. Fisheries IBI program staff also conducted a survey of lakeshore habitat on Bluewater Lake on July 18th 2024, following the Score the Shore survey protocols. The survey consisted of 37 survey sites evenly spaced 200 meters around the lake. Assessments were made in three habitat zones: Shoreline Zone (the shore-water interface to the top of the natural bank), Shoreland Zone (land-ward from shoreline to development structure or 100 feet), and Aquatic Zone (lake-ward 50 feet of shoreline). The average lakewide habitat score was 78.4 (±3.4) out of 100 possible, which indicates the lakewide shoreline condition is Moderate (70-79.9). Approximately 59 percent of the sites were developed with a mean score of 64.9 (±3.3) indicating shoreline habitat quality of developed sites is Poor (50-65.9), while undeveloped sites had a mean score of 98.2 (±1.0) with Excellent (92+) habitat quality. Data from this survey indicates Bluewater Lake is healthy as indicated by an exceptionally high FIBI score, well above the impairment threshold for aquatic life use determined for similar lakes. These results are similar to previous findings which indicated that Bluewater Lake is fully supporting aquatic life. Data from this survey will contribute biological information about the health of the fish community to the Mississippi River - Grand Rapids Watershed assessment process in coordination with MN Pollution Control Agency.

Bluewater Lake is located about 13 miles north of Grand Rapids and in the Chippewa National Forest. Fish production is limited due to low fertility associated with oligotrophic conditions. Bluewater Lake has a long history of trout management but has been primarily managed for Lake Trout since 1961. Management has consisted mainly of numerous stockings. Most stocked fish were given a specific fin clip to help differentiate between stocked and natural reproduction since 1990. Stocking was discontinued after 2017 due to poor returns from stocking and because natural reproduction appeared capable of maintaining the fishery. The 2016 lake management plan lists Lake Trout as a primary species of management with a deep-water gill net catch rate goal of 3.0/net. Quality size Smallmouth Bass have been sampled in most surveys and are listed as a secondary management species though there is no management goal. The 2022 targeted survey was conducted to evaluate the status of the Lake Trout population as well as a reference for the new Caribou Lake experimental regulation. Lake Trout are typically not abundant in any lake due to the nature of the cold, infertile lakes they inhabit. They often occupy deep, open water and can be difficult to sample, so low catches are not uncommon. Catches in deep-water gill nets have ranged from 1.3 to 4.3/net but have typically been near 3.0/net since 1980. The 2022 catch of 2.2/net was less than the management goal. No fin clipped fish were sampled. Captured trout ranged from 10.0 to 30.1 inches with an average length of 19.6 inches. The wide range of lengths suggests recruitment has been consistent. The lack of fin clips indicated these fish originated from natural reproduction. Deep-water gill nets may not reflect the numbers of other species, but Smallmouth Bass, Northern Pike and Tullibee catches resembled previous surveys and have never been high. The fishery provides good opportunities for anglers to catch large pike and bass. Both species have traditionally had quality size structure, similar to what was observed in 2022. Largemouth Bass were the only other species sampled in deep-water gill nets.

Lake Trout are the primary management species with a management catch rate goal of 3.0/net maintained through natural reproduction and stocking. Smallmouth Bass are a secondary management species with no defined goals. The lake management plan was last updated in 2016. The 2017 targeted survey was conducted to increase the sample size for Lake Trout genetic testing as well as sex and maturity data. Yearling Lake Trout have been stocked at a rate of 5 fish/surface acre (1,820) in odd years since 1991. All stocked fish were given a specific fin clip to differentiate between stocked age classes and natural reproduction. Multiple strains of Lake Trout have been stocked over time. An evaluation between Gillis and Mountain strains occurred from 2005 and 2009 with Mountain Lake strain exclusivity stocked since. Deepwater gill nets sampled 21 Lake Trout, at a rate of 2.3/net, exceeding the previous survey (1.9/net) yet below the lake management goal. Catches have typically been low, averaging 3.0/net since the biennial stocking began. Lengths ranged from 12.4 to 31.7 inches with a mean length of 24.2 inches. No distinguishing marks were identified during a field examination, similar to what was observed in past surveys. The limited number of Mountain Lake strain Lake Trout ever sampled indicates poor performance and survival. Sex and maturity was determined from 10 Lake Trout with the remainder (n=11) being alive and released. Immature fish were not abundant, one female and two males were sampled, while three mature females and four mature males were sampled. The male sample appeared to mature around 13 inches, though the sample size is small and may not be an accurate reflection. Naturally reproduced Lake Trout otoliths sometimes display slight crystallization, especially at early ages, providing only moderately confident age estimation. Hatchery reared Lake Trout almost always will have some degree of crystallization in the otoliths at early ages and cannot be aged accurately without the aid of a fin clip. Ages determined through otolith analysis from half of the fish caught were ages 4, 5, 7, 10, 13, 15, 16, and 19 present in the sample. The wide range of ages is similar to what was observed in the 2009 survey. Age 4 comprised 30% of the sample, while only one representative for the remainder of the ages was observed. The average length of age 4 was 12.9 inches, similar to age 4 fish from Caribou (12.6 inches). The sample size was too small to assess age at maturity, but all age 4 were immature and the remainder were mature. It appears maturity begins as early as age 5 in some individuals. The wide range of ages observed in the Lake Trout population indicates a history of natural reproduction and recruitment. It is unclear if the gaps in the age classes are consistent with a low density population or a representation of high exploitation rate. Genetic analysis was not finished by the report due date and will be included in the lake management plan.

Based on Minnesota DNR survey data, anglers target Northern Pike, Lake Trout, Yellow Perch, Hybrid Sunfish, and Smallmouth Bass in Bluewater. See the full species list above for catch rates, size structure, and quality scores.

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

Bluewater has a maximum depth of 120 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Bluewater is from 2024.

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