Thompson

This targeted survey was completed to determine extent of winterkill following the severe 2022-2023 winter. Trap netting results suggested that winterkill severity was low and restorative stockings were not warranted. Gamefish species present included Black Crappie, Bluegill, Largemouth Bass, and Walleye. The majority of fish collected for these species were larger individuals.

Thompson Lake is a 154-acre basin located four miles east of Barret in Grant County. It is a relatively shallow, fertile lake that is prone to occasional fish kills. Average and maximum depths were 16 and 22 feet, respectively. Water clarity has significantly increased and was 16 feet during the 2021 survey, which may be attributed to lack of precipitation and subsequent runoff. However, even with the increased water clarity aquatic vegetation continues to be limited. The current Walleye population (9.0/gill net) slightly declined from the 2015 survey but was still high when compared to similar lakes. Walleye grow fast, reaching 15 inches by age 3. Anglers should expect to find predominately large fish, which ranged from 19.1 to 26.8 inches, with an average of 22.1 inches. Fifty-six stock-length Largemouth Bass per hour were sampled, higher than all previous surveys. Size structure was impressive, with most bass exceeding 15 inches. The largest bass sampled was 18.7 inches and average length was 14.7 inches. Moderate numbers of Bluegill (4.7/trap net) were sampled in 2021, which have varied considerably in past surveys. Size structure was poor, even though growth was fast. This is because all Bluegill sampled were young. If fish can survive long enough they should reach sizes that would be of interest to anglers in a couple years. Although the 2021 survey was the second highest Black Crappie catch rate on record (2.7/ trap net), it is still quite low, as it has been in past surveys. Similar to Bluegill, crappies tend to be young and small but grow fast. Average length was only 5.2 inches but the largest sampled was 12.5 inches. Other species sampled were Common Carp, Green Sunfish and Yellow Bullhead.

Thompson Lake is a 150-acre basin located five miles north of Hoffman in Grant County. It is a relatively shallow, turbid, and excessively fertile lake that is prone to occasional fish kills. Diversity and abundance of rooted aquatic plants are limited. Aquatic vegetation provides critical habitat for many fish species. Strong winds and wave actions can result in re-suspension of fine silts and attached nutrients, stimulating frequent algal blooms. Water clarity and recreational uses can be seasonally impaired. Catch statistics from the 2015 survey suggest possible occurrence of a partial fish kill event in advance of the survey. This is most evident in Walleye, Bluegill, and Black Crappie catch data. Walleye fingerlings and yearlings have been stocked in odd-numbered years since 2003. Walleye catches were elevated during the 2015 survey with a catch rate of 12.0-fish/gill net. A few larger Walleye were present but the catch was largely comprised of juvenile fish no older than age two. These young fish were likely products of fingerling and yearling stockings in 2013 and early 2015. Bluegill catches declined from 12.0-fish/trap net in 2009 to 2.9-fish/trap net in 2015. Black crappie catches were also low in 2015. All Bluegill and Black Crappie catches were comprised of young fish. However, these young fish grow rapidly in this fertile basin. In 2015, average size was 6.9 inches for Bluegill and 8.4 inches for Black Crappie. The largest Bluegill measured was 9.8 inches. The largest Black Crappie measured 10.9 inches. Thompson Lake currently supports an excellent Largemouth Bass fishery. Spring 2015 electrofishing results indicated record-high bass abundance and exceptional size structure. Almost 25% of the electrofishing sample exceeded 15.0 inches and the largest bass collected measured 19.9 inches. The Yellow Perch population also exhibited a favorable size structure. Good numbers of 8.0- and 9.0-inch perch were collected with the largest perch measuring 11.0 inches. This population provides a unique angling opportunity because high-quality Yellow Perch populations are not common in the Glenwood Management Area. No northern pike have been captured since 1999. Limited aquatic vegetation and high water temperatures during summer months likely explain the absence of this cool water species. Other species sampled in low numbers include Common Carp, Black Bullhead, Yellow Bullhead, Hybrid Sunfish and White Sucker.

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

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

Thompson has a maximum depth of 22 feet and a mean depth of 16 feet, per Minnesota DNR data.

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

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