Round Lake is 72 acres in size and is located in west-central Hillsdale County approximately 6 miles west of the city of Hillsdale. Part of the St. Joseph River watershed, Round Lake has an inlet on its east side and outlets to Hemlock Lake to the west and Little Hog Creek to the north.
Marl is the dominant substrate type from shore out to the 10 foot contour and makes up approximately 10% of the total lake bottom. Over 80% of this lake's substrate is comprised of organic matter, with some scattered gravel and sandy areas near shore. Bulrush, white and yellow water lily, and several species of pondweed are the most abundant aquatic plants found in the lake, and they are all moderately abundant.
Round Lake is characterized as having steep drop-offs into deep water, and it has a maximum depth of 36 feet. Approximately 85% of the lake's surface area has water greater than 10 feet in depth. The water color is best described as clear to slightly turbid. The latest limnology survey (August 1980) showed that good oxygen levels existed at the thermocline. Temperatures ranged from 74�F at the surface to 45�F at the 36 foot depth. On the day of the survey, the thermocline occupied the layer of water approximately between the 16 and 21 foot depths. Dissolved oxygen concentrations in this layer of water ranged from 9 ppm to 5 ppm, respectively.
The shoreline is approximately one-third developed and about 30 mostly permanent residences exist on this lake. A state-owned public fishing site with a gravel boat ramp is located on the lake's northwestern shore. The undeveloped shoreline areas of Round Lake are a mixture of wetland shrubs, green ash, and red and silver maple trees.
The public access site at Round Lake was constructed in 1964. An electrofishing survey in 1965 resulted in a catch of several game fish species including bluegill, pumpkinseed sunfish, yellow perch, lake crappie, and largemouth bass. One 12-inch rainbow trout was also caught during the 1965 survey and likely entered the lake through the connecting channel with Hemlock Lake which has been stocked with rainbow trout since the mid-1950s. All game fish species caught in 1965 were reported to be in excellent condition and fishing pressure was estimated as moderate.
Round Lake was last surveyed in June 1989 with four standard 6 x 3-foot trap nets and two 125-foot experimental gill nets. Game fish species captured in descending order of abundance included bluegill (160), black crappie (8), largemouth bass (6), pumpkinseed sunfish (5), and rock bass (1). Although few largemouth bass were captured in trap and gill nets, numerous small bass were observed in the shallow areas of the lake.
Based on growth analysis using fish scales, bluegills caught during the 1989 survey exhibited growth rates above the state average (Table 1). Bluegills dominated the trap net catch, comprising nearly 70% of all fish species caught and averaging 7.1 inches each. Over 80% of the bluegills caught with trap nets were of an acceptable size to anglers (Table 1).
Yellow perch averaged 8.5 inches each and, as a group, exhibited a growth rate that is 1.0 inch above the state average (Table 1). No perch were caught in trap nets, but this species comprised over 70% by number and 66% by weight of the total gill net catch. Nearly 90% of all perch were of acceptable size to anglers (Table 1).
Although not enough fish were caught per age group to be statistically significant, black crappie and pumpkinseed sunfish exhibit above average growth trends. However, largemouth bass exhibit slow growth tendencies.
Both bluegill and perch are represented in each of the age groups II through VIII (Table 2). Only four age-V yellow perch were caught during the 1989 survey, which suggests that a weak year class may exist. Although few age-II fish of either species were caught in trap or gill nets, these smaller fish are much less vulnerable to netting.
The catch from the 1989 survey shows that a good species mix exists in this lake. Bluegill and perch growth rates and average sizes are quite impressive and these two species are likely underutilized by anglers.
Anglers interviewed during the 1989 survey reported good open-water fishing success for bluegill and crappie but catch few bass and pike. Ice fishing was rated as good by the locals but pressure was estimated as only light. One angler reported that good perch fishing opportunities existed in Round Lake while others were unable to catch this species consistently.
Round Lake presently supports populations of perch and bluegills that are of acceptable size to anglers. A water chemistry survey of Round Lake in 1980 showed that temperatures and dissolved oxygen levels favorable for rainbow trout growth and survival existed. This data, together with the absence of northern pike, make this lake a good candidate for the introduction of rainbow trout. An updated dissolved oxygen and temperature profile of Round Lake is planned in the summer of 1990. If water quality is found to be comparable to the 1980 data, it is recommended that rainbow trout be stocked to provide an additional angling opportunity. Subsequent surveys of this lake's fishery should be made to evaluate trout growth and survival as well as to monitor the growth rates of existing game fish.
Table 1.-Number, weight, catch per effort and percent legal size for species of fish taken with trap or gill nets from Round Lake, June 9, 1989.
Number Percent Weight Percent Catch Percent
of total of total per legal
Species fish number fish weight effort* size*
Trap nets
Bluegill 153 69.9 39.7 33.3 38.3 81.0
Black crappie 6 2.7 3.4 2.8 1.5 100.0
Largemouth bass 4 1.8 2.0 1.7 1.0 0.0
Warmouth 18 8.1 2.7 2.3 4.5 22.2
Pumpkinseed 5 2.3 0.9 0.8 1.3 60.0
Bullhead 1 0.5 1.5 1.3 0.3 100.0
Rock bass 1 0.5 0.2 0.2 0.3 100.0
Green sunfish 1 0.5 0.1 0.1 0.3 0.0
Longnose gar 18 8.1 16.7 14.0 4.5 ---
Bowfin 1 0.5 2.7 2.3 0.3 ---
Carp 6 2.7 36.6 30.7 1.5 ---
White sucker 7 3.2 12.8 10.7 1.8 ---
Total 221 100.0 119.3 100.0 55.6 ---
Gill nets
Yellow perch 98 72.1 33.2 66.0 49.0 87.8
Bluegill 7 5.1 1.7 3.4 3.5 71.4
Largemouth bass 2 1.5 0.5 1.0 1.0 0.0
Black crappie 2 1.5 1.3 2.6 1.0 100.0
Bullhead 3 2.2 0.6 1.2 1.5 33.3
Warmouth 8 5.9 1.0 2.0 4.0 12.5
White sucker 12 8.8 10.8 21.5 6.0 ---
Grass pike 3 2.2 0.8 1.6 1.5 ---
Spotted gar 1 0.7 0.4 0.8 0.5 ---
Total 136 100.0 50.3 100.0 68.0 ---
*Number of fish per trap-net or gill-net night.
*Percent legal size or acceptable size to harvest.
Table 2.-Percentage age frequency for two species of fish taken with trap or gill nets from Round Lake, June 9, 1989 (number of fish in parentheses).
Age group
Species II III IV V VI VII VIII
Bluegill 6 34 14 16 18 10 2
(3) (17) (7) (8) (9) (5) (1)
Yellow perch 13 34 20 7 13 11 2
(7) (19) (11) (4) (7) (6) (1)