O'Reilly

The 2012 lake management plan (LMP) indicated Largemouth Bass and Northern Pike were the primary management species while Black Crappie and Bluegill were secondary. The LMP goals were to maintain a Northern Pike catch at 5.0/gill net with 60 and 10% of the fish longer than 21 and 28 inches; maintain the gill-net catch for Largemouth Bass at 1.5/net and Black Crappie at 2.5/net. A targeted survey using gill nets was conducted in 2020 to assess the fish community and provide information for anglers. Black Crappie catches have ranged from 0/gill net in 1970 to 6.0/gill net in 1986 but have generally been comparable to lakes with similar habitat. The 2020 catch of 4.2/net exceeded the LMP goal and was the second highest on record. The sampled fish ranged from 6.1 to 10.9 inches and averaged 8.8 inches. Seven age-classes were estimated with fish ranging from age 2 to 9. Growth was slow but comparable to other lakes with similar habitat. Fish only averaged 8.1 inches by age 5. Bluegill are typically evaluated using trap nets and the best time to sample them is late spring or early summer. Though not the primary indicator gear for Bluegill, the gill-net catch was 2.7 fish/net. The sampled fish ranged from 3.8 to 8.9 inches and averaged 6.3 inches. No age and growth information was collected in this survey. The Bluegill habitat appears to be poor for producing good numbers of larger fish. Largemouth Bass are most efficiently sampled by spring night electrofishing which was not conducted in 2020. The gill-net catch was 1.8 fish/net, which met the LMP goal. The sampled fish ranged from 9.1 to 14.8 inches and averaged 12.1 inches. No age and growth information was collected in this survey. The lake appears to have the potential for providing bass fishing opportunities but large fish may be uncommon. Northern Pike gill-net catches have ranged from 2.8 fish/net in 1992 to 9.5 fish/net in 1974, 2000, and 2020. The catch in 2020 equaled the highest on record and distinctly higher than desired for the LMP goal. The sampled fish ranged from 10.7 to 35.0 inches and averaged 21.6 inches. Length distributions resulted in 49 and 11% of the sample longer than 21 and 28 inches, which nearly attained the LMP goals. Eight age-classes were present with fish ranging from age 1 to 9. Pike averaged 22.8 inches after four years of growth; which was above the statewide average of 20.5 inches. Despite higher catches, the population may benefit from a simple predator community with Tullibee as a prey source. Anglers are encouraged to restrain from harvesting pike exceeding 22 inches in order to improve the population. Tullibee can be difficult to sample because they frequently live suspended over deep water, an area the standard nets were not designed to sample. However, they are important to fish communities as a prey source for large predators. Tullibee gill-net catch rates have ranged from 0.5 fish/net in 2020 to 14.4 fish/net in 1986. The 2020 catch was the lowest on record. Though the 2020 catch was one of six times the catch has been less than 1/net, it was the fourth consecutive survey with very low catches. The three sampled fish ranged from 6.3 to 8.8 inches and had a mean length of 7.7 inches. The low catches appear to be a long-term trend for O'Reilly, which also occurred in many other lakes around the state. Yellow Perch are another important prey common to northern Minnesota lakes but very few have ever been sampled in O'Reilly Lake. In 2020, just one 5.8-inch perch was sampled in gill nets. Low perch numbers can limit predator numbers and the population would not attract anglers Other species sampled included Brown Bullhead, Pumpkinseed Sunfish, Rock Bass, Walleye, White Sucker and Yellow Bullhead.

O'Reilly Lake is a 202-acre lake located 5 miles northwest of Taconite, MN. The lake is the largest lake in a chain of three connected lakes including Shamrock and Island Lake. The lake is moderately developed with clear water and a Secchi disk reading of 13 ft. Previous water chemistry sampling indicated low fertility which negatively affects growth rates and abundance of the fishery. Primary fish species include northern pike, largemouth bass and panfish. The northern pike gill net catch rate was 4.7/net and was similar to the average for similar lakes. Catch rates in past assessments have varied from 2.8 to 9.5/net. Size structure was moderate and most fish sampled were less than 25 inches. One 34 inch fish was sampled indicating the lake has the potential to produce larger northern pike. Five year classes of northern pike were sampled with ages 2 to 5 and age 8 represented. Growth was similar to the statewide average and fish averaged 23.6 inches by age 5. Only one fish older than age 5 was sampled and size structure could be improved if a greater proportion of fish survived to older age classes. Angler harvest is likely limiting survival and size structure of the population. Largemouth bass were sampled by spring electrofishing and sampled 50 fish for a catch rate of 49.9/h, indicating a moderate to abundant population. This was the first assessment to sample largemouth bass by electrofishing. Ten fish were also sampled by gill nets or trap nets. Size structure was moderate with fish up to 17 inches sampled. Most year classes were sampled with fish up to age 9 indicating a population with good recruitment to older age classes. Growth was slightly slower than the statewide average with fish averaging 13.6 inches by age 6. The bluegill catch rate was 6.7/trap net and was slightly lower than the expected range for similar lakes. Catch rates have generally been higher and varied from 6.8 to 22.5/net. Size structure was poor and only one fish sampled was larger than 8 inches and most fish were less than 6 inches. Size structure has generally been poor in most assessments. Fish up to age 10 were sampled and most year classes were present. Growth was slower than the lake class average with fish only averaging 5.8 inches by age 7 and 6.8 inches at age 9. Bluegill rarely live beyond age 10 and although survival to older age classes appears good, slow growth limits the potential to produce fish larger than 8 inches. Black crappie catch rates were low, with catch rates of 1.2 and 1.3/net for gill nets and trap nets. Catch rates were within the expected range for similar lakes for both gears. Catch rates in past assessments have varied from 0 to 6.0/gill net. Although sample size was low size structure was good with fish up to 11 inches sampled. Seven age classes were present and fish up to age 11 were sampled. Growth was much slower than the statewide average with fish averaging 10.0 inches by age 8, compared to 12.3 inches at age 8 for the statewide average. Similar to bluegill, slow growth limits the potential to produce large black crappie. Common prey species such as yellow perch and tullibee were not abundant in O'Reilly Lake. No yellow perch were sampled in this assessment and catch rates have been less than 1.0/net when they have been sampled. Tullibee catch rate was 0.7/gill net which was less than the expected range for similar lakes. Tullibee catch rates in past assessments have varied from 0.7 to 14.4/gill net. Low abundance of prey species limits growth rates and abundance of predator species such as northern pike. Walleye have been stocked several times and have been sampled in very low numbers in past assessments. Walleye stocking was discontinued in 1988 due to low catch rates and lack of suitable prey to support additional predator species. No walleye were sampled in this assessment and O'Reilly Lake is best suited for northern pike, largemouth bass and panfish. Other species sampled by gill nets and trap nets include bowfin, brown and yellow bullhead, pumpkinseed sunfish, rock bass and white sucker. Nearshore seining and electrofishing also sampled Iowa and Johnny darters, bluntnose minnow, burbot, central mudminnow and tadpole madtom in addition to young-of-the-year gamefish species already sampled by gill net and trap nets. 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 harvesting fewer smaller fish and releasing medium and larger fish.

O'Reilly Lake is a small, rather deep (79 feet), clear water lake located in western Itasca County. The lake is best known as a good largemouth bass and northern pike lake. Walleye are present but are only occasionaly caught. O'Reilly has been open to tullibee netting but reportedly receives light pressure. Most of the tullibee run small (8-10 inches) and netting takes place late in the season. Trianophorus sp. (a yellow grub) has been found in many of the tullibee sampled in past years as well as this assessment. This species can be an excellent forage species for walleye and northern pike. Yellow perch, another prey species, have been observed in low numbers in past assessments. This was also the case in this assessment. Only one was sampled in the gill nets. Walleye have historically been sampled in very low numbers. Stocked only ocassionally, they were stocked for the last time in 1986 and 1988. In this assessment, only 3 walleye (0.5/gill net) were sampled, similar to the 1986 assessment which evaluated a period of no stocking. The walleye varied from 16.7-21.5 inches and had a mean length of 18.4 inches. Largemouth bass were captured in good numbers in this assessment. Most were small, however, varing from 5.1-15.0 inches. Electrofishing is a better tool to evaluate the bass population and should be used in the next assessment. Bluegill were sampled in numbers similar to past assessments. They varied from 3.8-8.4 inches and averaged 5.5 inches. Black crappie can be difficult to sample in summer assessments since they often suspend over deep water. This appears to have been the case in this assessment. They were sampled in gill nets in good numbers (2.7/set) while only 3 (0.3/trap set) were sampled in trap nets. They varied from 7.1-9.8 inches. Other species sampled were bowfin, brown and yellow bullhead, white sucker, rock bass and pumpkinseed sunfish.

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

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

O'Reilly has a maximum depth of 79 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in O'Reilly is from 2020.

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