Four

Lake Four (Seth Lake) is a shallow lake located approximately 5 miles southeast of Aitkin in a watershed of pastureland, rolling hardwoods, and a spruce wetland. The lake has an average depth of 8 feet and a maximum depth of 31 feet. There is no public access on the lake, however, there is private access through a campground on the east side of the lake. In the early 1990's, Lake Four was part of a management project that involved the removal of a large number of northern pike (2,681), and the stocking of a large number of yellow perch (38,113). The goal of the project was to improve the size structure of northern pike and bluegill populations. Theoretically, had the perch population flourished, they would have provided a forage base for the northern pike as well as predation pressure on an overabundant and stunted population of bluegills. The experiment was short lived and unsuccessful. The last two surveys (1999, 2009) have shown the fish community to be much the same as before the project. Northern pike abundance increased to 14 fish per gill net lift, which is high compared to other lakes of this type, and is the highest that has been observed on Lake Four. The average size of the northern pike was 20.6 inches, which is similar to observations made in 1996 and 1999. The largest northern pike sampled measured nearly 36 inches. Bluegill abundance was within the normal range for this type of lake at 22.2 fish per trap net. The average size of the bluegills has remained small, fluctuating between 4.6 inches in 1991 and 5.2 inches in 2009. The bluegill in Lake Four may not be able to grow beyond these sizes because of fishing pressure that targets the largest individuals. The black crappie abundance index of 4.0 per gill net is stable at a level that is normal for this lake class. The average size of the crappies was over 8 inches long with individuals measuring over 10 inches. The 2009 sample had fish from five different year-classes, which suggests consistent recruitment. Lake Four continues to support a population of largemouth bass with higher than average abundance based on the gillnet catch rates in 2009. The size structure of the population appears healthy, with a maximum size observed approaching 19 inches and an average length of around 14.5 inches. Angler behavior has the greatest potential for restructuring or protecting existing fish populations in Lake Four. For example, selectively harvesting smaller northern pike and voluntarily releasing pike over 24 inches is encouraged. Anglers are also encouraged to release the larger panfish and bass. Recycling these large fish has the greatest potential to improve the size structure of anglers' catches.

Seth Lake is a shallow lake located in a watershed of pastureland, rolling hardwoods, and a spruce wetland. There is a private access through the campground on the east side of the lake and there is no public access on the lake. Because of the limited access and a fish community with abundant small bluegill, Seth Lake was chosen for a management experiment aimed at increasing the size of bluegill through attempting to control the number of young-of-the-year bluegill. Controlling small bluegill numbers, which would allow for greater growth of those remaining, may be possible if predation pressure can be increased by increasing the abundance of yellow perch and reducing northern pike which prey upon perch. With this reasoning, over four thousand pounds of northern pike where removed and seven thousand pounds of yellow perch were stocked in 1992 and 1993. The results of this project were short term. Northern pike growth increased in 1993-95 following the removal of pike and stocking of yellow perch, possibly because they had more forage of yellow perch per individual. The stocked yellow perch may have been successful in limiting the successful production of yearling and young-of-the-year bluegills in 1992 and 1993. This may also have been part of a larger pattern of poor centrachid recruitment statewide. Whatever the cause, there was an increase in growth of young bluegills from 1993-1995, possibly as a result of the lower density. The perch stocking was not successful in establishing a population of significant abundance. There were just two yellow perch caught in the 1999 assessment. The number of predators left in the lake at the time of the stocking may have been too great to allow the perch population to take hold. The current fish community is much the same as before the removal and stocking experiment. Northern pike abundance was fairly stable at 10.8 fish per gill net lift, which is high compared to other lakes of this type. The average size of the northern pike was 21.1 inches, which is the same as that observed in 1996 and represents an increase over the 20.3-inch average of 1991. Bluegill abundance was still within the normal range for this type of lake at 18.5 fish per trap net. The average size of the bluegills has increased slightly from 4.6 inches in 1991 to 5.2 in 1996 and 5.0 inches in 1999. The black crappie abundance index of 4.8 per gill net is stable at a level that is normal for a lake in this class. About half of the fish were over 8 inches long and had average growth compared to statewide averages. However, no fish were caught that were larger than 9.5 inches. The 1999 sample had fish from five different year-classes, which suggests good recruitment. Like the bluegill population, the black crappie in Seth Lake may not be able to grow beyond these sizes because of fishing pressure that targets the largest individuals. Seth Lake continues to support a population of largemouth bass with higher than average abundance. The size structure of the population has changed to include more small individuals since the 1996 assessment. A pulse of larger bass of the 1984-1990 year-classes that was observed in the 1996 assessment has largely passed through the system and was not caught in 1999. This is probably because due to a natural cycle of recruitment and senescence rather than harvest by the angler. Largemouth bass abundance and size structure has been variable since the first survey in the 1983. The quality of the largemouth bass fishery will likely improve as the 1994 and 1995 year-classes get older and anglers practice catch and release bass fishing. More than any management activity, angler behavior has a great potential for restructuring the northern pike population. Selective harvest of smaller northern pike and the release of the larger predators will allow for the reduction in the number of smaller northern through cannibalism and an increase in the catch rates of larger fish.

Aitkin Area Fisheries personnel are conducting a project on Seth Lake to determine if changing the northern pike and yellow perch populations would lead to long-term changes in the fish community. The desired result is an increase in average sunfish size following a series of responses within the fish community. To this end, four thousand three hundred and sixty three pounds of northern pike were removed and 7,208 pounds of yellow perch were stocked in 1992 and 1993. The efforts to remove northern pike did not result in a decrease in abundance from 1991 to 1996. The removal of adult fish was compensated for by increased survival of the 1992 year class. Seventy percent of the northerns in this survey were four year old fish in the 20.0 to 22.9 inch range. The average length has increased from 20.3 inches in 1991 to 21.1 inches in 1996, due to a reduction in the number of smaller pike in the lake. Small northerns may be experiencing intense predation from the larger northerns which now may have little suitable alternative prey. Such reduction in survival benefits the fishery by reducing competition for prey among small northerns, which in turn results in faster growth of smaller northerns which can then grow to acceptable sizes for anglers. The success of the pike fishery on Seth Lake may depend on maintaining a minimal harvest level on larger northern pike. Lack of prey and an abundance of spawning and nursery habitat for pike will increase the tendency for anglers to detrimentally reduce the abundance of larger pike and produce a shift toward smaller, more abundant northern pike. The yellow perch population was decimated in the three years after stocking. Northern pike grew faster shortly after the yellow perch were stocked, and the pike looked plump. The loss of yellow perch will probably result in a return of leaner, slow-growing pike in the lake. Without yellow perch, the attempt to affect the bluegill population will likely not be successful. Additional sampling will be needed to track the bluegill population for any future changes. Black crappies were small, grew slowly and were caught in low numbers in this survey. The size structure of the population has decreased since 1983 and recruitment has become rather sporadic. The population in 1996 consisted mostly of 2 and 7 year old crappies. The abundant pike population may be reducing crappie survival. Growth has slowed considerably since 1983. Northern pike may also be competing with crappies for prey and thus reducing crappie growth. The catch of fish in the trap nets, including bluegills, decreased from 1991 to 1996. Either there were fewer fish near shore in 1996 or the nets did not fish as effectively. Regardless, bluegills continue to grow very slowly. The average 8 year old bluegill is not even 6 inches long. Future sampling will reveal the extent to which yellow perch impacted bluegill survival. The younger bluegills were too small at the time of this survey to sample effectively with the trap nets. Largemouth bass grew slowly when young and at normal rates when older, as was noted from the previous survey. Bass were caught more in the gill nets, which are fished away from shore, and bass are likely hunting on the outside edges of the dense vegetation. Big largemouth bass have been caught from the lake, and are presumably being protected by a catch and release ethic on Seth Lake.

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

We don't have a confirmed public access point on record for Four. Check the DNR LakeFinder page for current access details before you go.

Four has a maximum depth of 31 feet and a mean depth of 8 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Four is from 2009. Surveys this old should be treated with some caution — fish populations change over time.

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