Buffalo Lake is a 124-acre located near the Town of Dovray in Murray County. Buffalo Lake has a maximum depth of 8.5 feet, and typically has turbid water (Secchi depth = 1.0 feet). Buffalo Lake is occasionally susceptible to low dissolved oxygen levels during the winter, with the last documented winterkill occurring during the winter of 2009-2010. During this winter, dissolved oxygen levels dropped to 0.2 parts per million (ppm) by mid-January so the aeration system was not operated to encourage winterkill of Common Carp and other undesirable fish species. A winterkill check during the spring of 2010 captured six species of fish; however, Common Carp were not sampled despite seeing high numbers of them (27.5 per gill net) during the survey in the summer of 2009. Because of its susceptibility to winterkill, Buffalo Lake is managed primarily for Northern Pike and secondarily for Yellow Perch and Crappie because these species are more tolerant of low dissolved oxygen levels than other species such as Walleye. Northern Pike fingerlings have occasionally been stocked (2006 and 2010) to supplement the existing population; however, it is likely that Northern Pike naturally reproduce in this system because it has connected wetlands that provide spawning habitat. Yellow perch and crappie populations are self-sustaining and have not been stocked in the last decade. Buffalo Lake was surveyed the week of June 29, 2015 to monitor fish populations using two gill nets and eight trap nets.
Northern pike tend to do well in Buffalo Lake, as gill net catches have varied from 2.5 per gill net in 2009 to 12.0 per gill net in 2003, all of which exceed expected catch rates for similar lakes (0.0 to 2.0 per gill net) in the Windom management area. In 2015, the Northern Pike catch rate was within the historical range of catch rates (2.5 to 12.0 per gill net), as they were captured at a rate of 5.5 per gill net, the second highest catch rate observed on this lake. There are at least four year classes of Northern Pike present, suggesting that their population is sustained through natural reproduction. Additionally, young-of-the-year (YOY) Northern Pike (N=3) were captured in the nearshore survey, indicating that there was natural reproduction in 2015. Northern Pike are a decent size with lengths ranging from 16.5 to 30.2 inches and averaging 22.7 inches. Northern Pike were plump suggesting that forage is not limited in this system. The Northern Pike in Buffalo Lake should provide good opportunity for anglers and winter spearers alike.
In 2015, Yellow Perch were captured at a rate of 19.0 per gill net, which is the second highest catch rate observed in Buffalo Lake. Historic catch rates have varied from 0.5 per gill net in 2003 to 22.0 per gill net in 1998 and have averaged 12.8 per gill net since 1998. The 2015 catch rate is within the expected range of catch rates for similar lakes (3.3 to 30.4 per gill net) in the Windom management area. The majority of the Yellow Perch were small, ranging in length from 5.3 to 8.5 inches and averaging 6.3 inches. Eighty-nine percent of the yellow perch sampled were less than 7.5 inches in length. Yellow Perch were plump indicating that food is available. The perch population appears to be naturally reproducing in Buffalo Lake, as nearshore sampling captured 475 Age-0 Yellow Perch.
Abundance of Black Crappie in Buffalo Lake is trending downward as catch rates have decreased from 46.9 to 13.6 to 1.3 per trap net in 2003, 2009, and 2015, respectively. The 2015 catch rate of 1.3 per trap net is within the expected range of catch rates for similar lakes in the Windom management area (0.7 to 15.3 per trap net), but is well below the long term average of 15.5 per trap net. Black Crappie abundance tends to be boom-or-bust where a strong year class will account for the majority of the population at a given time. Three to four year classes of Crappie are present in Buffalo Lake, with lengths ranging from 4.6 to 14.5 inches and averaging 8.9 inches. It should be noted that when you have a high abundance of another panfish, like yellow perch, it is not surprising to see a low catch. Zero YOY Black Crappie were sampled in the nearshore survey suggesting that they did not reproduce in Buffalo Lake this year. Black Crappie were very plump indicating that ample forage is available to them. Historically, White Crappie have also been present in Buffalo Lake, but none were sampled in 2015.
Catch rates of Black Bullhead in 2015 were near the expected range of catch rates for similar lakes in gill nets (131.5 per gill net; expected range 30.3 150.6 per gill net) and in trap nets (121.8 per trap net; expected range 11.5 to 132.6 per trap net). Historic catch rates of Black Bullhead in gill nets have ranged from 18.5 per gill net in 2009 to 178.0 per gill net in 1998, and have averaged 105.3 per gill net since 1993. Historic catch rates of Black Bullhead in trap nets have ranged from 1.4 per trap net in 2009 to 347.0 per trap net in 1998, and have averaged 147.6 per trap net since 1993. Black Bullhead ranged in length from 3.7 to 13.3 inches and averaged 7.4 inches.
Two Walleye were captured in the gill net (21.0 and 21.7 inches), despite not being stocked by MNDNR. It is likely that these fish were illegally transferred by an angler. To avoid unintended introductions, anglers should be diligent about disposing of unused bait in the trash, and should report unpermitted movement of fish.
Consistent with the winterkill check done in 2010, zero Common Carp were captured during this survey. In the previous survey done in 2009, Common Carp abundance was high (27.5 per gill net). The aeration system was not run, per our guidance to Murray County, during the winter of 2009-2010 when dissolved oxygen levels dropped below 0.2 ppm by mid-January, with the intention of trying to decimate the abundant carp population. It appears this effort was successful.
Plants in the water and at the water's edge provide habitat, prevent erosion, and absorb excess nutrients. Shrubs, trees, and woody debris such as fallen trees or limbs provide good habitat both above and below the water and should be left in place. By leaving a buffer strip of natural vegetation along the shoreline, property owners can reduce erosion, help maintain or improve water quality, and provide habitat and travel corridors for wildlife.
Best management practices within the watershed (no-till farming, cover crops, buffer strips, targeted fertilizer application, reduced or metered tiling) would help reduce nutrients entering the lake. High nutrient and sediment input can cause algae blooms and reduce overall water quality. Any improvements in the watershed are likely to have positive impacts on the fishery.
Prepared by Jonah Dagel