Balsam Lake is a 710-acre lake located in central Itasca County, north of Taconite, MN. The lake has a maximum depth of 37 ft and a littoral area of 296 acres. One aspect of this survey was to collect data as part of a statewide study evaluating different walleye stocking strategies including fry, fryling and three densities of fingerlings. All stocked fish were marked with oxytetracycline (OTC) to determine the relative contribution of stocked fish and fish from natural reproduction.
Walleye gill net catch was 0.9/net, which was lower than the expected range for similar lakes. Catch rates in past assessments have also been low varying from 0 to 1.0/gill net. As part of the walleye stocking study, frylings were stocked at a rate of 150/littoral acre in 2001, fingerlings were stocked at 2 lbs/littoral acre in 2003, and fingerlings were stocked at 1 lb/littoral acre in 2005. In 2006, 11 fish were aged and only four (36 %) corresponded to stocked year classes. Fish from the 2005, year class were likely too small to be sampled effectively and all four fish corresponded to the 2003-year class. These fish were also found to carry the OTC marks, confirming that they were stocked fish. Walleye length frequency had two distinct groups; the 2003-year class that varied from 12 to 15 inches, and a second group of fish mainly from the 19966-year class that varied from 25 to 27 inches. The 1996-year class was a nonstocked year. Back-calculated length at age was not available for the 2006 survey, however growth in 2004 was similar to the statewide average.
Northern pike gill-net catch was 7.1/net, which within the expected range for similar lakes. Gill-net catch rates in past assessments have varied from 3.3 to 10.4/net. Size structure was generally poor and the majority of fish sampled were less than 24 inches. However a few larger fish up to 37 inches were sampled. Balsam Lake has the capability of producing large northern pike, and a 24 to 36 inch protected slot limit was implemented in 2006 to improve size structure. Growth was similar to the statewide average with fish averaging 25 inches by age five.
Black crappie gill-net catch was 2.6/net, which was toward the upper end of the expected range for similar lakes. Catch rates in past assessments have been highly variable from 2.0 to 9.1/gill net. Size structure was fairly good with fish up to 10 inches sampled. Recruitment was consistent and all year classes through age 8 were represented. Growth was slower than the statewide average with fish averaging 10 inches by age 8, compared to 12 inches by age 8 for the statewide average. Many of the lakes in this part of the county have a common thread of bog-stained water and slow growing black crappie populations.
Bluegill trap net catch rate has been increasing and was 40/net, which was toward the upper end of the expected range for similar lakes. Size structure was poor with few fish exceeding 8 inches. Growth was slower than the lake class average for ages 1 to 6, and faster than the average for ages 7 to 10. Bluegill average 8 inches by age 10.
Spring electrofishing sampled largemouth bass at 13.7 fish/hour, which was similar to the 2000 catch rate of 18.0/hr. Fish varied in length from 3 to 16 inches. Growth was similar to the statewide average with fish averaging 15 inches at age seven.
Yellow perch gill-net catch was 3.4/gill net and was within the expected range. Catch rates in past assessments varied from 0.8 to 5.1/net. Size structure was poor with no fish exceeding 9 inches.
Other species sampled include tullibee, rock bass, brown bullhead, pumpkinseed, Johnny darter, blackchin shiner, blacknose shiner, bluntnose minnow, golden shiner, longear sunfish, tadpole madtom, and white sucker.
The 2006 assessment was a full survey, which included vegetation sampling, substrate descriptions and water chemistry. Vegetation sampling described the abundance of 49 different aquatic and riparian plant species. Substrate was primarily sand and detritus with lesser amounts of rubble and gravel. Water chemistry analysis indicated total phosphorous of 0.03 ppm and total alkalinity of 91 ppm.
Lakeshore owners may affect fish populations not only through harvesting fish, but also through land use practices. It is important to leave a 30 to 50 ft buffer strip of native vegetation along the shoreline to prevent erosion and provide habitat for fish and wildlife. Nonfunctioning septic systems can also lead to water quality problems. Good water quality and fish populations are the direct result of good land use practices. Anglers can also help to improve the size structure of the fish community by practicing selective harvest.