Duck

Duck Lake is a 290-acre lake located on the north side of the city of Madison Lake in Blue Earth County. Duck Lake has a maximum depth of 25 feet. A county-maintained public access is located on the south end of the lake near the county park. Most of the shoreline has been altered by residential development and high-quality nearshore habitat and diverse aquatic vegetation are scarce. Duck Lake is primarily managed for Black Crappie, Bluegill, and Northern Pike and secondarily for Largemouth Bass. Duck Lake is designated as a Tier-1 lake and will be surveyed as part of a regularly scheduled monitoring program at a frequency of every 3 years. The 2025 survey was completed the week of June 9, 2025, using 5 gill nets, 9 trap nets, and electrofishing. Water quality parameters were also measured. A total of 137 Black Crappies were sampled with the gill nets for a catch rate of 27.4/net. Catch rates have varied from 3.0/net to 35.7/net with an average of 17.2/net since 1995. Black Crappie in 2025 ranged from 5.4 to 9.8 inches with an average of 6.3 inches. Black Crappie were also abundant in the trap nets with a total of 129 sampled for a catch rate of 16.1/net. Black Crappie size structure in trap nets was similar to the gill net sample except for the presence of fish that exceeded 12 inches with the largest measuring a trophy length of 16.5 inches. The presence of an equally abundant White Crappie population suggests that these outlier fish may have been the result of hybridization between the two species. Black Crappie from both gears ranged from age-2 to age-12 with 8 year-classes present. Age-2 to age-7 Black Crappie were well represented, indicating good consistent recruitment. Bluegills were sampled at a rate 0 15.3/trap net in 2025. Catch rates have varied from 15.3/net to 95.1/net with an average of 59.2/net since 1995. Bluegill ranged from 4.3 to 8.3 inches with an average of 7.0 inches. Bluegill ranged from age-3 to age-10 with 8 year-classes present. Approximately 88% of Bluegill sampled were age-3 or age-4. Bluegill growth was moderate with an average length of 6.9 inches at age-4. The Bluegill population in Duck Lake has a history of high abundance, poor size structure, and slow growth. Northern Pike were sampled in low numbers in 2025. A total of just 11 were sampled with the gill nets for a catch rate of 2.2/net. This was the second lowest catch rate on record since 1995 and continued a trend of declining Northern Pike catch rates since 2011. Northern Pike ranged from 15.3 to 36.5 inches with an average of 24.4 inches. Three additional Northern Pike up to 36.6 inches were sampled with the trap nets. Approximately 55 percent of Northern Pike were longer than the minimum length limit of 24 inches. The declining catch rates coupled with the lack of smaller, younger fish suggests that recruitment has been limited in recent years. A total of 23 Largemouth Bass were sampled with standard boat electrofishing for a catch rate of 25.0/hour. Largemouth Bass ranged from 6.2 to 20.4 inches with an average of 13.4 inches. Overall, the Largemouth Bass population in Duck Lake is limited, likely due to a lack of nearshore habitat and low annual recruitment. White Crappies were abundant in Duck Lake and outnumbered Black Crappies in both net gears. A total of 195 White Crappie ranging from 5.9 to 13.5 inches were caught for a catch rate of 24.4/trap net. White Crappie are often present in Waterville Area lakes but are rarely considered anything more than a rare member of the fish community. Studies have shown that hybridization is common when both species occur in a water body and often the resulting offspring grow faster and can reach a larger size than pure Black Crappies or White Crappies. This may explain the presence of multiple fish over 15 inches in the 2025 sample when most fish from both species were small. Yellow Perch were sampled at a rate of 20.4/net, which the second highest catch between 1995 to 2025. During that time, catch rates varied from 4.3/net to 21.3/net with an average of 12.9/net. Yellow Perch were mostly small with a maximum of 8.4 inches and an average of just 6.6 inches. The increased Yellow Perch relative abundance was a good sign in 2025, and could be a result of low Northern Pike numbers. Black Bullhead numbers were low in both gears (10.8/gillnet and 2.6/trap net). Trap net catch rates have varied wildly with a low of 0.1/net and a high of 84.8/net since 1995. The past two surveys have shown high Black Bullhead numbers 69.8/ trap net in 2019 and 84.8/ trap net in 2022, the low numbers of 2025 were a welcome sight. Other species sampled in 2025 include Bowfin (1.5/trap net), Common Carp (21.4/gill net), Freshwater Drum (5.2/gill net), Walleye (1.5/trap net), and White Sucker (0.1/trap net). Water clarity was poor with a secchi reading of 2.0 feet due to abundant free-floating algae. Water dissolved oxygen and temperature readings ranged from 9.8 ppm and 68.2 degrees Fahrenheit at the surface to 0.2 ppm and 60.8 degrees Fahrenheit at 21 feet. A thermocline was detected at around 9 feet. Anglers can play an important role in maintaining or improving a fish population by practicing selective harvest. Selective harvest allows for the harvest of smaller fish for consumption, while encouraging the release of medium to large fish that may contribute to natural reproduction. This practice helps maintain balance in the fish populations and provides anglers the opportunity to catch more and larger fish in the future. Additionally, smaller fish often taste better and have fewer contaminants than larger, older fish from the same water body. Shoreline property owners also play an important role in the overall health of an aquatic ecosystem, including the fish population. Natural shorelines, including vegetation, woody debris, and bottom substrates, provide valuable habitat for fish and wildlife, help maintain water quality, and reduce bank erosion. Cattails and bulrushes are particularly beneficial for fish spawning, rearing, and feeding. By leaving natural shorelines unaltered or restoring them to natural conditions, shoreline property owners are doing their part to maintain or improve a healthy ecosystem in the lake and protect the resource for future generations. -Tyler Fellows, fisheries specialist

A targeted survey of nearshore fish species in Duck Lake was conducted on June 14-15, 2022, by DNR 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 nine stations and a 15-foot seine was used at one station. Nearshore sampling captured 17 species of fish including one species that is intolerant of disturbance (i.e., Iowa Darter) and two that are tolerant of disturbance (i.e., Black Bullhead, Fathead Minnow). The nearshore data were combined with trap net and gill net data from a 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., Iowa Darter, Blackchin Shiner, Rock Bass), while other species are tolerant of degraded conditions (e.g., Black Bullhead and Fathead Minnow). 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 provide evidence that the fish community in Duck Lake is adversely impacted by stressors, as indicated by an FIBI score below the impairment threshold for aquatic life use determined for similar lakes. These results are similar to a survey in 2019, but both scores are lower than the previous assessment for Duck Lake completed in 2015, when Duck Lake scored equal to the impairment threshold. Data from this survey will contribute biological information about the health of the fish community to the Mississippi River - Mankato Watershed assessment process in coordination with MN Pollution Control Agency.

Duck Lake is a 290-acre lake located on the north side of the city of Madison Lake in Blue Earth County. The lake has a maximum depth of 25 feet with approximately 80% less than 15 feet. A county-maintained public access is located on the south end of the lake near the county park. Most of the shoreline has been altered by residential development and high-quality nearshore habitat and diverse aquatic vegetation are scarce. Duck Lake has generally poor water clarity and frequent algal blooms caused by elevated nutrient levels. Duck Lake is primarily managed for Black Crappies, Bluegill, and Northern Pike and secondarily for Largemouth Bass. The management plan calls for an annual stocking of 60,000 Northern Pike fry into the adjacent wetland. A trap is deployed every spring between the lake and the wetland to collect Northern Pike for egg take needs. Duck Lake is designated as a Tier-1 lake and will be surveyed as part of a regularly scheduled monitoring program at a frequency of every 3 years. A standard survey is used for sampling a wide range of fish species during the summer months using standard methods (i.e., standard time of year, set sampling stations, taking water clarity readings and oxygen/temperature profiles, etc.) and gears (i.e., lake survey gillnets, trap nets, and spring electrofishing for Largemouth Bass). The 2022 survey was completed the week of June 13, 2022 using 6 gill nets, 9 trap nets, and 85 minutes of boat electrofishing. Water quality parameters were also measured. A total of 155 Black Crappies were sampled with the gill nets for a catch rate of 25.8/net, indicating high numbers were present. Black Crappie catch rates varied from 3.0/net to 35.7/net with an average of 15.7/net from 1995 to 2022. Catch rates have climbed to an average of 23.7/net in the four most recent surveys after averaging just 5.2/net from 1995 to 2006. Black Crappie lengths in 2022 ranged from 4.2 to 9.4 inches with an average of 7.4 inches. Size structure was poor with less than half the sample over 8 inches and none over 10 inches. Black Crappies were also abundant in the trap nets with a total of 316 sampled for a catch rate of 35.2/net. The size structure was similar to the gill net sample except for the presence of 6 fish that exceeded 12 inches with the largest measuring a trophy length of 17.3 inches. The presence of an equally abundant White Crappie population suggests that these outlier fish may have been the result of hybridization between the two species. Black Crappie from both gears ranged from 1 to 9 years-old with 9 year-classes present. Two- to eight-year-old fish were well represented, indicating good consistent recruitment. Bluegills were also abundant in the 2022 survey with a total of 402 sampled with the trap nets for a catch rate of 44.7/net. Bluegill catch rates have varied from 23.0/net to 95.1/net with an average of 65.5/net since 1995. Bluegills ranged from 4.7 to 8.0 inches with an average of 7.0 inches. Almost all Bluegills were over 6 inches. Bluegills ranged from 2 to 9 years old with 7 year-classes present. Approximately 44% of Bluegills sampled were 7 years old and almost all were older than 3 years old. Bluegill growth was slow with an average length of 6.0 inches at year 4. The Bluegill population in Duck Lake has a history of high abundance, poor size structure, and slow growth. Efforts to improve size structure and growth should be considered. Northern Pike were sampled in low numbers in 2022. A total of just 11 were sampled with the gill nets for a catch rate of 1.8/net. This was the lowest catch rate on record since 1995 and continued a trend of declining Northern Pike catch rates since 2011. Northern Pike ranged from 20.6 to 35.9 inches with an average of 28.5 inches. Nine additional Northern Pike up to 37.8 inches were sampled with the trap nets. Northern Pike from both gears ranged from 2 to 9 years old with 7 year-classes present. The 7-year-old age group from 2015 was particularly abundant. Northern Pike growth was fast with an average length of 24.2 inches at year 3. The declining Northern Pike catch rates coupled with the lack of smaller, younger fish suggests that recruitment has been limited in recent years. Duck Lake is subject to southern zone Northern Pike regulations of 2 fish daily and a 24-inch minimum length limit. A total of 23 Largemouth Bass were sampled with standard boat electrofishing for a catch rate of 17.0/hour. Catch rates have varied from 9.0 to 28.3/hour with an average of 20.2/hour in four samples since 2000. Largemouth Bass ranged from 5.7 to 18.8 inches with an average of 12.5 inches and approximately 14% were over 15 inches. Largemouth Bass were 2 to 14 years old with 10 year-classes present and growth was moderate. White Crappies were abundant in Duck Lake and even outnumbered Black Crappies in the trap net sample. A total of 354 White Crappie ranging from 5.6 to 12.4 inches were caught for a catch rate of 39.3/net which more than doubled the previous high catch rate of 15.3/net in 2019. White Crappies are often present in Waterville Area lakes but are rarely considered anything more than a rare member of the fish community. Studies have shown that hybridization is common when both species occur in a water body and often the resulting offspring grow faster and can reach a larger size than pure Black Crappies or White Crappies. This may explain the presence of multiple fish over 15 inches in the 2022 sample when most fish from both species were small. Yellow Perch were sampled at a rate of 21.3/net, indicating moderate to high numbers were present. The Yellow Perch were mostly small with a maximum of 8.0 inches and an average of just 6.5 inches. Surprisingly, most were older with approximately 76% over 3 years old and some up to 8 years old. Yellow Perch growth was slow with an average length of 6.4 inches at year 4. The increased Yellow Perch relative abundance was a good sign in 2022, especially coupled with low Northern Pike numbers. Black Bullheads were common in both gears (19.8/gillnet and 84.8/trap net). Trap net catch rates have varied wildly with lows of 0.1/net and 6.4/net and highs of 84.8/net and 79.5/net since 1995. Often, Black Bullheads recruit in high numbers following some disturbance such as a winterkill. No known winterkills were listed in the lake management plan so the high Black Bullhead numbers must have been the result of something else. Low Yellow Bullhead numbers also point to some sort of instability since they are often the dominant bullhead species in larger, healthier lakes. Other species sampled in 2022 include Bigmouth Buffalo (1.6/trap net), Bowfin (0.2/trap net), Common Carp (1.7/gill net), Freshwater Drum (20.2/gill net), Golden Shiner (0.3/gill net), Walleye (0.6/trap net), White Sucker (0.1/trap net), and hybrid sunfish. Water clarity was poor with a secchi reading of 2.0 feet due to abundant algae. Dissolved oxygen and water temperature readings ranged from 8.2 ppm and 71.2 degrees Fahrenheit at the surface to 0.3 ppm and 65.5 degrees Fahrenheit at 20 feet. A thermocline was detected at around 12 feet. Anglers can play an important role in maintaining or improving a fish population by practicing selective harvest. Selective harvest allows for the harvest of smaller fish for consumption, while encouraging the release of medium to large fish that may contribute to natural reproduction. This practice helps maintain balance in the fish populations and provides anglers the opportunity to catch more and larger fish in the future. Additionally, smaller fish often taste better and have fewer contaminants than larger, older fish from the same water body. Shoreline property owners also play an important role in the overall health of an aquatic ecosystem, including the fish population. Natural shorelines, including vegetation, woody debris, and bottom substrates, provide valuable habitat for fish and wildlife, help maintain water quality, and reduce bank erosion. Cattails and bulrushes are particularly beneficial for fish spawning, rearing, and feeding. By leaving natural shorelines unaltered or restoring them to natural conditions, shoreline property owners are doing their part to maintain or improve a healthy ecosystem in the lake and protect the resource for future generations. - Sky Wigen, fisheries specialist

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

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

Duck has a maximum depth of 25 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Duck is from 2025.

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