Loon Lake is a 1,048-acre mesotrophic (moderately fertile) lake located in north-central Otter Tail County. The town of Vergas, MN abuts the northeast shoreline of the lake. The immediate watershed is composed primarily of agricultural land interspersed with hardwood woodlots. The lake has a maximum depth of 105 feet; however, 56% of the lake is 15 feet or less in depth. The lake contains several distinct basins, all connected by narrow passages. The shoreline length is 15.5 miles. The secchi disc reading for this survey was 13.7 feet. Previous secchi disk readings have ranged from 6.8 to 14.5 feet.
A majority of the shoreline of Loon Lake is developed. The development consists primarily of homes, cottages, and resorts. A DNR owned concrete public access is located off of County Road 35 along the northeast shoreline of the lake. Shoal water substrates consist primarily of sand and gravel. Emergent plants (hardstem bulrush, common cattail, and wild rice) are prevalent throughout Loon Lake. Emergent plants are important because they provide valuable fish and wildlife habitat and are critical for maintaining good water quality. Emergent plants provide spawning areas for fish species such as Northern Pike, Largemouth Bass, and panfish. They are also important nursery areas for all species of fish. Because of their ecological importance, emergent plants may not be removed without a DNR permit.
Loon Lake can be ecologically classified as a bass-panfish type of lake and this is reflected in the assemblage of the fish community. Northern Pike, Largemouth Bass, and Bluegill are the dominant gamefish species in the fish community. The prolificacy of these species can be attributed to the quality and quantity of suitable habitat that is available for these species.
A high-density Northern Pike population exists. Northern Pike abundance has historically been high and size structure poor. Eight percent of the pike were 24.0 inches or greater in length. Pike ranged in length from 12.7 to 31.2 inches with an average length and weight of 19.2 inches and 1.6 pounds. Northern Pike attain an average length of 20.4 inches at five years of age.
Data from a spring electrofishing assessment indicate that a moderately-high density Largemouth Bass population exists. Age data indicate that reproduction is consistently good. Bass ranged in length from 3.8 to 18.1 inches. Largemouth Bass attain an average length of 11.9 inches at four years of age.
Bluegill abundance has historically remained at a moderate to high level. Bluegill size structure improved significantly from previous surveys. Fifty-seven percent of the sample was 7.0 inches or greater in length. Bluegills attain an average length of 6.9 inches at seven years of age.
Walleyes ranged in length from 14.8 to 25.7 inches with an average length and weight of 19.4 inches and 2.5 pounds. Walleyes attain an average length of 15.2 inches at four years of age.
Anglers can maintain the quality of fishing by practicing selective harvest. Selective harvest encourages the release of medium to large-size fish while allowing the harvest of more abundant smaller fish for table fare. Releasing the medium to large fish will ensure that the lake will have enough spawning age fish on an annual basis and will provide anglers with more opportunities to catch large fish in the future.