Cottonwood Lake is a shallow (maximum depth of 11 ft.), 155-acre lake located in the City of Windom in Cottonwood County. The lake is connected to Warren Pond and Warren Lake which have historically been used to manage water levels in Cottonwood Lake, which is connected to the City of Windom's water supply aquifer. Cottonwood Lake is managed primarily for Walleye and secondarily for Black Crappie, Bluegill, Yellow Perch and Largemouth Bass. Cottonwood Lake was surveyed the week of July 25, 2016 to monitor fish populations using three gill nets and nine trap nets. The Largemouth Bass population was not assessed in this survey.
The 2016 Walleye catch rate was near the lower end of the expected range of catch rates for similar lakes. The catch rate was 2.7 per gill net, a decrease from 10.7 per gill net in 2012, and below the long term average of 5.9 per gill net. Cottonwood Lake had heavy angling pressure and reportedly good walleye fishing during the winters of 2014-2015 and 2015-2016 that likely impacted Walleye abundance. Sampled Walleyes were large ranging in length from 12.7 to 26.0 inches and averaging 19.7 inches. Walleye in Cottonwood Lake were relatively old as 63 percent of sampled Walleye were age-8 or older. Walleye averaged 13.5 inches at age-3 indicating normal growth. Walleye yearlings that were stocked during the fall of 2016 should provide a quality angling opportunity in the near future.
In 2016, Black Crappie were captured at a rate of 3.9 per trap net, which is within the expected range of catch rates for similar lakes (1.2 to 20.5 per trap net), but is a decrease from the 2012 catch rate of 15.8 per trap net and is below the long term average of 16.8 per trap net. Lengths of Black Crappie ranged from 5.8 to 10.0 inches and averaged 7.9 inches. Black Crappie abundance is relatively low but they should be able to produce a year class if conditions are favorable.
The Bluegill catch rate decreased from 22.5 per trap net in 2012 to 1.0 per trap net in 2016, which is below the expected range of catch rates for similar lakes (1.2 to 20.0 per trap net) and below the long term average of 5.8 per trap net. Lengths of Bluegill ranged from 4.5 to 8.4 inches and averaged 5.7 inches.
The 2016 catch rate of Yellow Perch was 11.3 per gill net, a decrease from the 2012 catch rate of 65.7 per gill net, but within the expected range of catch rates for similar lakes (2.7 to 25.0 per gill net). Yellow Perch ranged in length from 5.6 to 8.2 inches and averaged 7.3 inches. The decline in Yellow Perch abundance was likely the result of predation by the abundant large Walleye that were present in 2015 and 2016.
The Black Bullhead catch rate was 273.0 per gill net, which was the second highest catch rate recorded on Cottonwood Lake. Black bullheads averaged 6.6 inches long. The Channel Catfish Catch rate was 3.3 per gill net, which is the highest recorded catch rate. Channel Catfish ranged from 8.8 to 15.5 inches and averaged 11.8 inches. It is possible that we will see black bullhead abundances decrease if channel catfish abundance increases. Other species sampled included Common Carp, White Sucker, Bigmouth Buffalo, and Pumpkinseed.