Rock

Rock Lake is a 1,048-acre lake located about eight miles northeast of Detroit Lakes in central Becker County. The lake periodically experiences winterkill of varying degrees. Very light winterkills, where a few dead fish are observed at the outlet in the spring, are relatively common. Property owners reported dead fish in the spring of 2023. A targeted fisheries survey was conducted in May 2023 to observe the severity of the winterkill. Dead fish of all species were observed while surveying. Trap nets captured Northern Pike, White Sucker, Tadpole Madtom, Yellow Perch, and three species of bullhead, all species which are more tolerant to low oxygen conditions. Bullheads were abundant. Northern Pike were caught in good numbers with an average length of 20 inches. Unfortunately, Rock Lake appears to have experienced a significant winterkill for Bluegill, Black Crappie, and Largemouth Bass during the 2022-2023 winter. This would be the first major winterkill since the winter of 1995-1996. As a result, Walleye, Largemouth Bass, Bluegill, and Black Crappie were reintroduced during 2023. Angling opportunities for Northern Pike are still available, but it will take a few years to have quality fishing for other species.

Rock Lake is a 1,048-acre lake located about eight miles northeast of Detroit Lakes in central Becker County. It is locally noted for good panfish angling and fair Walleye, Largemouth Bass, and Northern Pike fishing between winterkill events. Unfortunately, a severe winterkill occurred in the winter of 2022-2023, so please use caution with these results as the fish populations have changed since this survey was completed in July 2022. Walleye catch rates in Rock Lake have continued a slow decline since initial surveys. The 2022 gill net catch matched a historic low set in 2016 of 2.0 per net. This is below the lake's historic average of 6.5 per net. However, large fish dominate the population with the average Walleye sampled being 22.4 inches. Lengths of sampled fish ranged from 19.1 inches to 27.6 inches. Walleyes 20 inches or larger made up 88% of the fish sampled. Northern Pike abundance has been increasing since the early 2000's. The gill net catch rate of 16.6 per net was a record for the lake and much higher than the lake's average of 5.7 per gill net. The average length of sampled Northern Pike was 19.3 inches, but fish up to 33.0 inches were sampled. Abundant spawning habitat will likely keep the Northern Pike population above the historical average. The trap net catch for Bluegills averaged 34.1 per set in 2022, which is slightly below the historical average for the lake. Bluegills averaged almost seven inches and were abundant over six inches. The 2015 year-class remains strong and is averaging 7.0 inches. Black Crappies were sampled in moderate numbers with an average length of 8.6 inches, but fish up to 12.0 inches were sampled. Largemouth Bass were sampled in low numbers and lengths ranged from 9.6 to 16.5 inches. It is important to note that nets do not sample bass well and electrofishing is the preferred method for assessing bass populations, but electrofishing was not part of this survey. The Yellow Perch gill net catch rate remains below the historical average. Yellow Perch average length was 6.5 inches and only one fish over ten inches was sampled. Other sampled species included Black, Brown, and Yellow Bullhead, Pumpkinseed, and White Sucker.

Rock Lake is locally noted for good panfish angling and fair Walleye, Largemouth Bass, and Northern Pike fishing between winterkill events. Even though light to moderate kills have occurred fairly frequently, severe winterkills have occurred about every 15 years in Rock Lake. The last severe winterkill occurred in 1996. Severe kills usually result in the loss of most or all gamefish and panfish with only bullheads and possibly a few Northern Pike and Yellow Perch surviving. This is what happened in Rock Lake in 1996. In spring of 1996, following this winterkill, the DNR restocked the lake with broodstock Bluegills, Black Crappies, and Largemouth Bass. Walleye fry were also stocked. Northern Pike and Yellow Perch survived in strong enough numbers to naturally repopulate the lake. Since this time light to moderate kills have happened in 2001, 2011, and 2014. Northern Pike test net catch rates remained near their historic highs. High Northern Pike numbers may be suppressing recent Walleye recruitment to the fishery. Although there are high numbers of small Northern Pike, there are also some large specimens in the population. Northern Pike averaged almost 18 inches long, but one fish was nearly 36 inches in length. The younger age groups may be more acceptable to anglers in the next 2 to 3 years. Bluegill also had a historic high test net catch, with an average length of 6.7 inches. Bluegill were found to take 7 years to reach 8 inches long. A modest population of Black Crappie exist, with an average size of around 8 inches. It was found that 10-inch-long Black Crappie were about 7 to 8 years old. Largemouth Bass that were sampled ranged in lengths from 8 to 14 inches. Though the Walleye population is slightly lower than it has been in recent surveys, the average size of Walleyes is the highest it has ever been. The average size Walleye caught in Rock Lake is 19.3 inches in length and weighs 2.4 pounds. The largest Walleye caught in 2016 was 26.5 inches long and weighed 6 pounds. Rock Lake is lightly developed and much of the shoreline remains in a natural state. Aquatic vegetation, including large bulrush stands, remains relatively undisturbed and provides excellent fish and wildlife habitat. In the fall, Rock Lake attracts ducks and duck hunters for these same reasons. The Buffalo River runs through it adding another interesting characteristic to the lake. If future development occurs on Rock Lake, efforts should be taken to minimize disturbance to these natural features and aesthetics of the lake to conserve habitat and protect water quality.

Based on Minnesota DNR survey data, anglers target Northern Pike, Black Crappie, Bluegill, Largemouth Bass, and Walleye in Rock. See the full species list above for catch rates, size structure, and quality scores.

Minnesota DNR records list public access for Rock. Check the DNR LakeFinder page for the launch type and directions before you go.

Rock has a maximum depth of 18 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Rock is from 2022.

No invasive species are on record for Rock in Minnesota DNR data. Always clean, drain, and dry your equipment to help keep it that way.