Rush Island

A targeted survey of nearshore fish species in Rush-Island Lake was conducted on August 16, 2021, 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 10 sampling stations, but three stations were sampled from the boat due to site conditions. Similarly, a 50-foot seine was used to sample one station, a 15-foot seine was used at five stations, and site conditions prevented the use of seines at four stations. Nearshore sampling captured 14 species of fish including four species that are intolerant of disturbance (Banded Killifish, Blackchin Shiner, Blacknose Shiner, Iowa Darter) and no species that are tolerant of disturbance. The nearshore data were combined with trap net and gill net data from a June 2021 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 (Blackchin Shiner, Iowa Darter, and Rock Bass), while other species are tolerant of degraded conditions (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. For additional information on the FIBI, search for "lake index of biological integrity" on the mndnr.gov website. Results from this survey indicate that the fish community in Rush-Island 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 will be considered when the biological health of the lake is assessed during the Big Fork River Watershed assessment process, which will be completed in coordination with MN Pollution Control Agency.

Rush Island Lake is a 296 acre lake located 4 miles west of Spring Lake, MN. The lake is lightly developed and has a good public access on the south shore. The lake is connected to Birdseye Lake and then to Sand Lake by Rush Island Creek. Rush Island is a hard-water lake with moderate clarity and fertility. The 2013 lake management plan listed Northern Pike and Walleye as primary management species, with Bluegill and Black Crappie as secondary management species. A standard lake survey was conducted in June 2021 to assess the status of the fish community and to evaluate the effectiveness of Walleye fry stocking. Rush Island Lake has typically produced high numbers of Northern Pike with poor to fair size structure. The 2021 gill-net catch was well above the expected range for similar lakes and was a record high for Rush Island. Size structure remained poor; fish ranged from 12.6 to 33.1 inches with an average length of 20.9 inches. Ages 1-8 were represented in the sample, with age 3 the most frequently sampled. Growth was similar to the statewide average with pike reaching 22.7 inches at age 4. Rush Island provides good opportunity to catch numbers of pike under 22 inches. The Walleye gill-net catch was below average compared to lakes with similar habitat, but fairly typical for Rush Island. Size structure was favorable; Walleye ranged from 11.5 to 26.9 inches with an average length of 18.2 inches. Six year classes from ages 2 through 10 were represented in the sample. Only one fish corresponded to a non-stocked year. Growth was similar to the statewide average with Walleye exceeding 16 inches after 5 years of growth. Walleye fry had been stocked in odd-numbered years since 2017. Prior to that, Walleye fingerlings or yearlings were stocked in odd-numbered years. Stocking appears to support a low-density Walleye population. Rush Island Lake has a history of extremely high Yellow Perch catches in previous surveys. The 2021 catch rate was a record low of 25/net. The sharp decline in perch numbers is likely related to the record high catch of Northern Pike. Yellow Perch size structure was modest; sampled perch averaged 6.2 inches. The Bluegill trap-net catch rate was average compared to similar lakes. Size structure was fair; sampled fish ranged from 3.5 to 8.7 inches with an average length of 6.6 inches. Eight percent of the sampled fish exceeded 8 inches. Ages 2-9 were represented in the sample, with age 5 the most frequently sampled. Growth was considered fast with Bluegill averaging 6.7 inches after 5 years of growth. Rush Island Lake provides fair angling opportunities for moderate-sized Bluegill. Gill-net and trap-net catches for Black Crappie were low compared to similar lakes, but typical for Rush Island. The few crappie sampled were small, averaging 7.7 inches from gill nets and 4.8 inches from trap nets. A spring targeted survey would likely provide better information on the crappie population. Other species sampled in test-nets included Black, Brown and Yellow Bullhead, Bowfin, Largemouth Bass, Pumpkinseed, Rock Bass, Tullibee and White Sucker.

Rush Island Lake is a 296 acre lake located 4 miles west of Spring Lake, MN. The lake is lightly developed and has a good public access on the south shore. The lake is connected to Birdseye Lake and then to Sand Lake by Rush Island Creek. Rush Island Lake is in ecological lake class 31. Other area lakes in this class include Little Bowstring, Cedar and Little Turtle Lakes. The northern pike gill-net catch was above the expected range at 11.5/net. Catch rates have varied from 1.9 to 16.7/net in previous assessments. Catches have exceeded the lake class third quartile in four of the past five surveys. Size structure was fairly poor; gill-net sampled pike ranged from 17.5 to 27.6 inches, with a mean length of 21.8 inches. Ages 2-7 were identified from scale samples. Growth was similar to the statewide average with pike reaching 23.3 inches at age 4. The walleye gill-net catch was within the expected range, but down from the previous assessment at 1.8/net. Catch rates have varied from 0.2 to 8.2/net in previous surveys. Size structure was modest and no preferred-length (20 inches and over) fish were captured. Sampled walleye ranged from 13.8 to 19.9 inches with a mean length of 17.3 inches. Ages 4, 5 and 7 were identified from scale samples, with 9 of 11 fish (82%) corresponding to years of fingerling stocking. Growth was similar to the statewide average with walleye reaching 14.0 inches at age four. The lack of preferred-length walleye and northern pike in the test-nets may be an indication of high angler harvest. The yellow perch gill-net catch was above the lake class expected range at 101.7/net, but similar to the previous assessment and the long-term average for the lake. Size structure was poor; sampled perch ranged from 5.2 to 9.2 inches, with a mean length of 6.8 inches. Only 3% of perch exceeded 8 inches. The bluegill trap-net catch rate was within the expected range at 7.1/net. Size structure was poor; sampled fish ranged from 2.0 to 8.4 inches with a mean length of 5.4 inches. Only 5% of bluegill exceeded 8 inches. Bluegill catch rates did not exceed the lake class first quartile until the two most recent assessments. Bluegill were not aged in this assessment, but historical information suggests bluegill growth and size structure was better in surveys prior to 1990. The gill-net catch rate for tullibee was above the expected range at 7.0/net. Catch rates in previous assessments have varied considerably, from 0.2 to 8.0/net. Sampled tullibee ranged from 7.5 to 17.9 inches with a mean length of 11.9 inches. Other species sampled in test-nets included black and yellow bullhead, bowfin, hybrid sunfish, largemouth bass, pumpkinseed sunfish, rock bass and white sucker. As part of a statewide IBI (index of biotic integrity) project, back-pack electrofishing and shoreline seining was used to sample nearshore fishes not normally captured in traditional test-nets. Additional fish sampled with IBI gears included Iowa darter, Johnny darter, black crappie, blackchin shiner, bluntnose minnow, central mudminnow, creek chub, golden shiner and tadpole madtom.

Based on Minnesota DNR survey data, anglers target Walleye, Rock Bass, Northern Pike, Bluegill, and Yellow Perch in Rush Island. See the full species list above for catch rates, size structure, and quality scores.

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

Rush Island has a maximum depth of 32 feet and a mean depth of 19 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Rush Island is from 2021.

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