Shamrock Impoundment

A lake population assessment was completed on Shamrock Lake in July of 2008 as directed by the Operational Planning portion of the 2001 Lake Management Plan. The Operational Plan had listed 2005 as the next assessment date, but due to the increased workload of the Lanesboro Office the assessment was postponed until 2008. The impoundment was sampled with five standard trap-net sets that were set on July 16, 2008 and lifted the following day. Largemouth bass and northern pike populations were sampled during the day with an electrofishing boat on September 4, 2008. Black crappie and bluegill dominated the fish community in Shamrock Lake in 2008 and have dominated the trap net catch in every assessment dating back to 1986. The abundance of both black crappie and bluegills has increased dramatically since the 2000 assessment. However, average size has declined slightly for bluegills and to a much greater degree for black crappies. Abundance of both species far exceeds the 75% quartile for Lake Class 42. Mean weight however falls below the 50% quartile for lakes of similar type. Northern pike were also sampled in the trap nets and with electrofishing gear and their numbers were low, as has been historically the case, with trophy size fish present. Largemouth bass catch per effort (CPE) also increased dramatically since 2000 and is at the highest level since 1986. The average size of the bass collected in 2008 also increased from 2000 and is the largest average weight for largemouth bass ever collected in Shamrock Lake. One young-of-year largemouth was also captured while completing the shoreline electrofishing station.

A fish population assessment was conducted on Shamrock Lake during the summer of 2000 per the 1997 lake management plan. Fish samples were collected using five standard trap nets set overnight between July 12 and 13; the entire lake was sampled once with an electrofishing boat on September 5.The most common species collected were bluegill and black crappie. Small numbers of largemouth bass and northern pike were also collected. In addition, the single yellow perch in the trap net sample represents the first record of this species in Shamrock Lake. Black bullheads have not been collected since 1990.Populations of both bluegill and black crappie are high for lakes like Shamrock Lake, and both populations have developed a quality size structure. Although only eight northern pike were captured, average size was good and growth rate is above statewide average for this species.

A fish population survey was conducted on Shamnrock Lake in the summer of 1996. This survey was conducted to update fish population information since the last survey (1990). Five trap nets were set for two days in July and the lake sampled with an electrofishing boat on the morning of September 19. Shamrock Lake has a fish community dominated by panfish species, mainly bluegill and black crappie. The major predators in the lake are largemouth bass and to a lesser extent, northern pike. The bluegill population currently has a quality size structure. More than half of the fish caught in the trap nets were larger than or equal to 7.5 inches in length. Growth rate of bluegill in Shamrock Lake is above statewide average for this species. Though few crappies were caught in this assessment, it is likely that most of the crappie in the lake were suspended away from the heavy shoreline vegetation beds, and therefore not likely to be caught in the survey nets.The largemouth bass population has increased since 1990. However, it also appears that there are fewer larger bass than there were in 1990. Conversely, northern pike have declined in abundance since 1990.Another good sign for Shamrock Lake is that no bullheads, or other rough fishes, were caught during this assessment.

Based on Minnesota DNR survey data, anglers target Northern Pike, Largemouth Bass, Black Crappie, Yellow Perch, and Bluegill in Shamrock Impoundment. 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 Shamrock Impoundment. Check the DNR LakeFinder page for current access details before you go.

Shamrock Impoundment has a maximum depth of 15 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Shamrock Impoundment is from 2008. Surveys this old should be treated with some caution — fish populations change over time.

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