Shamrock

The 2012 lake management plan (LMP) indicated Largemouth Bass and Northern Pike were primary management species while Black Crappie and Bluegill were secondary. The LMP goals were to maintain a Northern Pike size distribution with 60% and 10% of the sample longer than 21 and 28 inches, and improve Bluegill size distribution to have more than 40% of the sample longer than 6 inches with some 8-inch fish. The purpose of the 2020 targeted survey was to assess the fish community and provide information to anglers. Black Crappie catches have ranged from 0/gill net in 1974 to 5.7/gill net in 1986. Despite only three fish being sampled in 2020 (1.0/net) it represented the highest catch since 1992. The fish ranged from 6.2 to 9.3 inches and averaged 7.2 inches. Two age-2 and one age-6 fish were estimated from scales. Growth was slow compared to similar lakes but the sample size was very low. Bluegill are typically evaluated using trap nets to sample them is late spring or early summer. Though not the primary indicator gear for Bluegill, the gill-net catch was 2.0/net. The sampled fish ranged from 4.1 to 7.4 inches and averaged 4.9 inches. Sample size was too low to evaluate the LMP size distribution goal. No age and growth information was collected. Largemouth Bass are most efficiently sampled by spring night electrofishing which was not conducted in 2020. The gill-net catch was 0.7/net, which was above average for the lake. The two fish were 14.4 to 18.3 inches. No age and growth information was collected. Northern Pike gill-net catches have ranged from 2.0/net in 1992 to 7.0/net in 2000. The 2020 catch of 6.7/net was higher than desired. High catches are often associated with slower growth and smaller average sizes. The sampled fish ranged from 14.1 to 33.1 inches and averaged 23.7 inches. The length distributions essentially met the LMP goal as 50 and 20% of the sample were longer than 21 and 28 inches. The seven age-classes had fish from age 1 to 8 represented. Pike averaged 22.9 inches by age 4; which was above the statewide average. It appears the simple predator community and availability of Tullibee as prey has buffered density concerns for now. Tullibee can be difficult to sample because they frequently live suspended over deep water, an area the survey nets were not designed to sample. This can result in highly variable catches from one survey to the next. Tullibee are important to fish communities as a prey source for large predators. Gill-net catch rates have ranged from 0.7/net in 1982 and 1992 to 26.0/net in 1974. The 2020 catch was the second highest on record at 17.7/net. The sampled fish ranged from 6.7 to 11.8 inches and averaged 9.6 inches. Though aging structures were not collected, it appears multiple age-classes were present based on the length distribution. Yellow Perch is another important prey species common to northern Minnesota lakes but very few have ever been sampled in Shamrock. In fact, none have been sampled by gill nets since 1992. It is possible some perch smaller than what the survey nets effectively sample exist but it appears they are not important component of the fish community. The entire chain of lakes has consistently had very low catches for perch. Smaller lakes often have simple fish communities and lower potential for fish production. Consequently, it is relatively easy for anglers to overharvest fish and negatively affect the fish community. Anglers are encouraged to restrict harvest for all species, particularly the larger individuals, in order to maintain or improve size distributions. Harvest of pike under the North-Central Zones 22 to 26 inch protected slot limit is encouraged because these individuals are often overabundant and can have negative effects on other fish species.

Shamrock Lake is a 59-acre lake located 5 miles northwest of Taconite, MN. The lake is the middle lake in a chain of three connected lakes including O'Reilly and Island Lake. The lake is moderately developed and has clear water with a Secchi disk reading of 14 ft. Previous water chemistry sampling indicated low fertility which negatively affects growth rates and abundance of the fishery. Primary fish species include northern pike, largemouth bass and panfish. The northern pike gill net catch rate was 5.0/net and was equal to the average catch rate for similar lakes. Catch rates in past assessments have varied from 2.0 to 7.0/net. Size structure was good for fish up to 26 inches; however no larger fish were sampled. Five year classes of northern pike were sampled and growth was similar to the statewide average with fish averaging 24 inches by age 6. Largemouth bass were sampled by spring electrofishing and sampled 14 fish for a catch rate of 42.0/h, indicating a moderate population. This was the first assessment to sample largemouth bass by electrofishing. Three fish were sampled by gill nets or trap nets. Size structure was moderate with fish up to 14 inches sampled. Growth was slightly slower than the statewide average with fish averaging 14 inches by age 6. Growth and size structure were similar to previous assessments. The bluegill catch rate was 3.7/trap net and was lower than the expected range for similar lakes. Catch rates have generally been low varying from 3.8 to 10.8/net in past assessments. Size structure was poor with no fish larger than 7 inches sampled. Growth was slower than the lake class average with fish only averaging 5.9 inches by age 8. Bluegill rarely live beyond age 10 and since growth in Shamrock Lake is slow it is unlikely that the lake can produce many bluegill larger than 8 inches. Black crappie catch rates were low, with catch rates of 0.3 and 1.3/net for gill nets and trap nets. Catch rates in past assessments have varied from 0 to 5.7/gill net. Size structure was poor with no fish larger than 9 inches sampled. Growth was slow with fish only reaching 7.1 inches at age 5 compared to 9.5 inches for the statewide average. Common prey species such as yellow perch and tullibee were not abundant in Shamrock Lake. No yellow perch were sampled in this assessment and they have only been sampled in gill nets once in six assessments. Tullibee catch rate was 2.3/gill net which was between the first quartile and median of 1.0 and 3.0/gill net. Tullibee catch rates in past assessments have been 4.0/ gill net or less in the last four assessments. Low abundance of prey species limits growth rates and abundance of predator species such as northern pike. Other species sampled by gill nets and trap nets include pumpkinseed sunfish, rock bass, yellow bullhead and white sucker. Lakeshore owners may affect fish populations not only through harvesting fish, but also through land use practices. It is important to leave a 30 to 50 ft buffer strip of native vegetation along the shoreline to prevent erosion and provide habitat for fish and wildlife. Nonfunctioning septic systems can also lead to water quality problems. Good water quality and fish populations are the direct result of good land use practices. Anglers can also help to improve the size structure of the fish community by harvesting fewer smaller fish and releasing medium and larger fish.

Shamrock Lake is a small 59 acre lake located four miles north of Taconite, MN. Due to the small size of the lake, the fish community is much more susceptible to over-harvest. Shamrock Lake is part of a three lake chain that includes Island and O'Reilly. O'Reilly Lake is the only lake with a public access. The lake management plan indicates largemouth bass and northern pike as the primary species of management with black crappie and bluegill as secondary species. Largemouth bass have never been assessed with spring electrofishing which is the most effective method. The goal for the lake was to maintain a net catch rate of 0.8 fish/net which average for this type of lake. In 2000, the management goal was not attained when the catch rate was 0.3 fish/net. However, only one fish was caught and it was 17.5 inches. No fish were sampled in the trap nets.The northern pike net catch exceeded the management goal with a catch of 7.0 fish/net. Prior to this assessment, catch rates have varied from 2.0 to 4.3 fish per net since 1974. Northern pike lengths ranged from 17.8 to 30.1 inches and averaged 22.1 inches. Five year classes were sampled with fish ranging from age 2 to age 6. The 1997 year class represented 56% of the sample. After four years of growth, northern pike averaged 23.4 inches which is above the statewide average of 20.5.In 2000, the black crappie trap-net catch was 1.2 fish/net which is about average for this type of lake. Although low, the trap-net catch was the highest on record. The fish ranged from 4.3 to 10.4 inches and had a mean length of 7.6 inches. Four year classes from age 1 to age 6 were represented. Growth was below statewide averages for all year classes. Due to low sample sizes it is difficult to determine the health of the black crappie population. The bluegill trap-net catch (5.8/net) was within the expected range for lakes like Shamrock. Previous assessments have observed catch rates fluctuating from a low of 3.8 fish/net in 1992 to a high of 10.8 fish/net in 1974. Bluegill ranged from 3.7 to 7.6 inches with a mean length of 5.3 inches. Fish were not aged during the 2000 assessment.Walleye have not been stocked in the chain of lakes since 1988. Six walleye were captured that resulted in a gill-net catch rate of 2.0 fish/net which is the highest ever sampled. There were four fish from the 1996 year class and two from the 1991 year class, both non-stocked years. The population is not likely to produce much of a fishery because of poor walleye habitat and low yellow perch numbers.Other species observed during the population assessment included bowfin (dogfish), brown bullhead, pumpkinseed sunfish, rock bass, tullibee, white sucker, and yellow perch. Excluding tullibee, these species were generally low in abundance and similar to previous assessment levels. Tullibee gill-net catch was 4.0 fish/net which exceeded the lake class average.To promote and maintain healthy fish populations, pollution needs to be controlled. Fish habitat is directly affected by water quality. Nutrients, sediments and other waste can drastically alter the chemical and physical characteristics of a lake. People often associate water quality problems in a lake with agricultural, forestry or industrial practices within the watershed. Although these can be areas of concern, lakeshore property owners may also contribute to water quality problems. Some examples include putting in sand beaches, removing shoreline trees and vegetation, fertilizing lawns, and mowing their lawns down to the lakeshore. Proper land use practices by everyone will help insure that this fishery can be enjoyed by future generations.

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

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

Shamrock has a maximum depth of 55 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Shamrock is from 2020.

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