|Nearest Town: Windom
Primary County: Cottonwood
Survey Date: 07/23/2012
Inventory Number: 17002200
|Did you know? Lake rehabilitation projects reclaim waters suffering from habitat degradation and overpopulation of some fish species.|
|Species||Number of fish per net||
Average Fish Weight (lbs)
Normal Range (lbs)
|Black Bullhead||Trap net||41.50||11.5 - 132.6||0.37||0.2 - 0.4|
|Gill net||82.33||30.3 - 150.6||0.21||0.2 - 0.4|
|Black Crappie||Trap net||15.75||1.2 - 20.5||0.25||0.2 - 0.5|
|Gill net||23.67||1.4 - 13.8||0.20||0.2 - 0.4|
|Bluegill||Trap net||22.50||1.2 - 20.0||0.21||0.1 - 0.4|
|Channel Catfish||Trap net||2.00||N/A||1.38||N/A|
|Common Carp||Trap net||0.25||1.0 - 5.5||3.31||1.4 - 4.6|
|Gill net||6.00||1.0 - 13.8||3.50||0.8 - 3.7|
|Largemouth Bass||Trap net||0.12||0.2 - 0.7||1.76||0.3 - 1.5|
|Northern Pike||Trap net||0.62||N/A||4.80||N/A|
|Gill net||2.33||1.1 - 8.0||3.46||1.8 - 3.4|
|Pumpkinseed||Trap net||5.38||0.3 - 4.9||0.14||0.1 - 0.2|
|Walleye||Trap net||0.75||0.5 - 3.0||0.46||0.8 - 2.3|
|Gill net||10.67||2.3 - 18.1||2.89||1.0 - 2.3|
|White Sucker||Trap net||0.12||0.3 - 2.6||2.65||1.0 - 2.0|
|Gill net||0.67||0.8 - 6.5||2.33||0.9 - 2.0|
|Yellow Bullhead||Trap net||0.25||0.5 - 2.5||0.39||0.3 - 0.7|
|Yellow Perch||Trap net||5.25||0.3 - 3.8||0.12||0.1 - 0.3|
|Gill net||65.67||2.7 - 25.0||0.12||0.1 - 0.3|
|Species||Number of fish caught in each category (inches)|
|For the record, the largest Brown Bullhead taken in Minnesota weighed 7 lbs., 1 oz. and was caught: |
Statistics: 24.4" length
Fish Stocked by Species for the Last Ten Years
|1 - indicates fish purchased and stocked by private citizens and sporting groups.|
|2 - indicates fish purchased by the DNR for stocking.|
|Stocking Fish Sizes|
|Fry - Newly hatched fish that are ready to be stocked usually called "swim-ups". Walleye fry are 1/3 of an inch or around 8 mm.|
|Fingerling - Fingerlings are one to six months old and can range from a size of one to twelve inches depending on the species. Walleye fingerlings range from three to eight inches each fall.|
|Yearling - Yearling fish are at least one year old. A one-year-old fish can range from three to twenty inches depending on the species. Walleye yearlings average from six to twelve inches.|
|Adult - Adult fish are fish that have reached maturity. Depending on the species, maturity can be reached at two years of age. Walleye reach maturity between the ages of four and six years.|
Cottonwood Lake is a 155-acre lake located in the City of Windom in Cottonwood County. The lake has a maximum depth of 11.0 feet and belongs to MN DNR class 43, which are small shallow lakes with high nutrients and low visibility (often called hypereutrophic). The watershed surrounding Cottonwood Lake is mainly agricultural (~70%) with the remaining land use being native grasses (~20%), open water and wetlands (~8%), and urban (~2%) areas. Cottonwood is managed primarily for walleye while largemouth bass, black crappie, bluegill, and yellow perch are managed secondarily. A fish population assessment was conducted in July of 2012 with 3 gill nets, 9 trap nets, backpack electrofishing, and beach seining to collect fish and assess the fish community. The results of the fish community sampling are below.
In 2012 the walleye catch rates were 10.7 fish per gill net and 0.8 fish per trap net both of which are within the normal ranges for class 43 gill nets and trap nets. The gill net catch rate of 10.7 fish per net is slightly above the long-term management goal of maintaining a catch rate at 10 fish per gill net. Walleye in the gill net and trap net sample (n=38) ranged in length from 7 to 30 inches with an average length of 20 inches in the gill net sample and 11 inches in the trap net sample. An average length of 20 inches in the gill net sample is very rare for SW MN lakes as walleye populations do not usually persist long enough to achieve average lengths that high. Of the 29 walleye analyzed to determine age, 10 age groups were present. Not only did the walleye persist long enough to reach sizes greater than 20 inches, but they also reached 15 inches after 3.5 years of growth indicating good growth of the walleye in Cottonwood Lake. The size structure of the fish in the sample showed this as well with 94% of the fish being greater than 15 inches, 35% being greater than 20 inches, 9% being greater than 25 inches, and 3% being greater than 30 inches (trophy sized fish). Given that the walleye population is able to produce fish greater than 25 inches indicates a population of fish that is foraging successfully and is very healthy. The overall health of the population was good. Overall, the walleye population in Cottonwood Lake is better than anticipated and is meeting all of the MNDNR's long-term management goals for abundance and size structure. The walleye population appears poised to maintain a healthy and abundant population of larger fish with the presence of an abundant age 4 year class (57% of the sample) that is likely to persist to a much older age (fish as old as 10 years were seen in the sample). Anglers should be pleased with walleye fishing in Cottonwood Lake as long as the fish take a lure.
Historically, the black crappie population was very abundant in Cottonwood Lake in the early 1990s with trap net catch rates of 32.3 fish per net in 1990 and 21.3 fish per net in 1994. In 1998, the population abundance was very low with a catch rate of 2.0 fish per gill net and 2.0 fish per trap net. Since 1998, the population has gradually recovered after stocking with a current catch rate of 23.7 fish per gill net and 16.8 fish per trap net. The gill net catch rate of 23.7 fish per net is 1.7 times the normal catch rate range of 1.4 to 13.8 fish per gill net while the trap net catch rate is within the normal range for lake class 43 (1.2 to 20.5 fish per trap net). Black crappie caught in 2012 ranged in length from 5 to 10 inches and are the result of 2 strong year classes shown in the length frequency distribution. The size structure of the fish in the sample indicates a population that is dominated by smaller fish in the 8 to 10 inch range. As the population matures, and if natural reproduction continues, the population should attain a more balanced size structure with all sizes present. The health of the population was very good. Overall, the black crappie population is currently meeting the DNR management goals of maintaining a fishable population with consecutive survey catches above 2.0 fish per gill net.
Bluegill are relatively rare as a managed species in southwestern Minnesota due to lakes that are characterized as shallow, turbid, and generally devoid of aquatic vegetation that provides habitat for bluegill to nest and successfully spawn. Historically, Cottonwood Lake was just like many lakes in southwest Minnesota that had a sparse population of bluegill, and the past surveys had catch rates below 8 fish per trap net. Bluegill were last stocked in 1991 and that stocking has perpetuated an anemic population until now. The trap net catch rate in 2012 was 22.5 fish per trap net which was greater than the upper normal catch range of 1.2 to 20.0 fish per trap net. Additionally, the bluegill population had 2 or 3 year classes with fish ranging in length from 4 to 9 inches with an average length of 6 inches. The size structure of the population is very good. Also, the health of the bluegill in the sample was excellent. If reproduction continues within the lake, the population could start to regularly produce fish over 8 inches. The reason for the bluegill explosion is most likely tied to aquatic vegetation, historical aquatic vegetation abundance in Cottonwood Lake was rare but currently aquatic vegetation is returning and producing favorable habitat for bluegill in the lake. Local reports from anglers over the summer of 2012 suggest that many 5 to 6 inch bluegill were caught. Continued improvement of the bluegill population will help to produce a unique bluegill fishery within the city of Windom. Anglers in southwestern Minnesota who like fishing for bluegill should give Cottonwood Lake a try.
During the 2012 survey only 6 largemouth bass were collected with night electrofishing and gill nets. Largemouth bass were first stocked in Cottonwood Lake in 1991. Largemouth bass were stocked again into the lake in 1998. Since 1991 largemouth bass have always been present in the lake at a relatively low abundance. The historical night electrofishing catch rates were 12.0 fish per hour in 1994 followed by 10.0 fish per hour in 1998, then 4.0 fish per hour in 2002, and finally 4.2 per hour in 2012. The size structure of the largemouth bass population favored larger fish greater than 15 inches. Additionally, the health of the largemouth bass was excellent. It appears that the low abundance population of largemouth bass in Cottonwood Lake is doing very well, but may need some additional stocking to increase the abundance of fish in the population. Usually catch rates greater than 20.0 fish per hour are considered good catch rates with anything below 20.0 indicating a population that is in need to additional stocking, or is influenced by low habitat suitability to reproduce naturally and sustain a population. Most likely the largemouth bass population is able to reproduce adequately in Cottonwood Lake, but the amount of predators in the lake reduces the largemouth bass young-of-the-year to levels that do not amount to an abundant adult population later on. Nearby Warren Lake is connected to Cottonwood Lake and used as a rearing pond for walleye fingerlings in the Windom Fisheries Management Area. Each fall the lake is drained and walleye are harvested for stocking into area lakes with excess (if any) to lakes around the entire state. In the fall of 2012, we found a very healthy population of largemouth bass (8 to 10 inches) in Warren Lake that were most likely from Cottonwood Lake, therefore, those fish were returned to Cottonwood Lake to help boost the population. Overall, the largemouth bass population is doing well in Cottonwood Lake and is currently producing fish in the 13 to 20 inch range with an average length of 16 inches which is between a 2 and 4 pound average.
The yellow perch population in Cottonwood Lake is self-sustaining. Yellow perch were only stocked 3 times, once in 1983, again in 1984, and most recently in 1998 to help boost the population. Historical DNR fish survey catch rates show a yellow perch population that was stagnant from 1955 to 2002 with catch rates between 0 and 15.5 fish per gill net and 0 and 1.7 fish per trap net while catch rates between 2.7 and 25.0 fish per gill net and 0.3 and 3.8 fish per trap net are considered normal for lake class 43. Therefore, the yellow perch population prior to 2003 was considered to be in low to low normal abundance. However, in 2008 the catch rates increased considerably to 55.3 fish per gill net and 2.9 fish per trap net followed by another increase in 2012 to 65.7 fish per gill net and 5.3 fish per trap net. The current catch rates are both greater than the upper normal catch rate range for gill nets (25.0 fish per net) and trap nets (3.8 fish per net) indicating a current yellow perch population that is in the highest abundance ever observed in Cottonwood Lake. Fish caught in the gill net and trap net sample ranged in length from 5 to 9 inches with an average length of 7 inches in the gill nets and 6 inches in the trap nets. The size structure indicates a population that is dominated by fish smaller than 8 inches. Additionally, the length frequency distribution indicates a population that is currently made up of 2 age groups of fish which are most likely the offspring of the dominant year class in the 2008 survey. The yellow perch population appears poised to maintain high levels over the next 2 to 3 years. A yellow perch population in high abundance will be good for the walleye and northern pike populations as well as yellow perch anglers. Yellow perch angling could be very good over the next 2 years on Cottonwood Lake if the current population survives.
Other non-managed species sampled in gill nets, trap nets, backpack electrofishing and seining in July, 2012 were black bullhead (n=302), common carp (n=20), channel catfish (n=17), johnny darter (n=2), northern pike (n=12), pumpkinseed (n=18), white sucker (n=3), and yellow bullhead (n=2).
Overall, it appears that walleye, black crappie, bluegill, and yellow perch are doing very well in Cottonwood Lake. The largemouth bass population appears to be experiencing some kind of stress that is reducing its abundance. Whether it is a real reduction in population abundance or just reduced catch rates during 2012 needs to be further determined during the next survey in 2016. If the catch rate remains low in 2016, then additional largemouth bass may be stocked by the DNR to boost the population. The health, high abundance, and 20 inch average length of the walleye population is the current bright spot in the 2012 fish sample for Cottonwood Lake. Anglers should look forward to continued improvement in the number of walleye larger than 16 inches caught in Cottonwood Lake over the next 2 years due to nearly 60% of the fish being that size or larger. Walleye anglers in southwestern Minnesota should consider Cottonwood Lake as a destination for walleye angling over the next 2 to 3 years; current conditions are ripe for success.
Prepared by Nate Hodgins
|For more information on this lake, contact:||Lake maps can be obtained from:|
For general DNR Information, contact:
DNR Information Center
500 Lafayette Road
St. Paul, MN 55155-4040
TDD: (651) 296-6157 or (888) MINNDNR
Turn in Poachers (TIP):
Toll-free: (800) 652-9093