Thompson Lake - Emiquon
Info / Fulton County
Family Friendly
Yes
Handicap Access
No
Boat Fishing
Yes - Electric trolling motors only
Boat Ramps
Yes
Boat Rentals
No
Camping
No
Picnicking
Yes
Skiing
No
Swimming
No
Trout Stocking
No
Zebra Mussels
Location 4000 acres
Fishing Outlook
Largemouth Bass
Average
In 2024, the Largemouth Bass population was sampled by 79 fish by electrofishing. The Largemouth Bass population was defined by an average year of recruitment with 10 fish sampled from 3.1 to 8.0 inches. The fall 2024 electrofishing survey indicated that the Largemouth Bass population density has continued the dramatic drop since 2020. The 2024 collection rate of stock size bass over 8 inches) dropped to .32 fish per minute and 50 pounds per hour. This was a decline from the 2.5 fish per minute and 246 pounds per hour collected in 2020. Then the collection dropped from 1.4 fish per minute in 2021 at 155 pounds per hour, to .67 fish per minute at 87 pounds per hour in 2022, and down to .44 fish per minute at 65 pounds per hour in 2023. The goal is a collection rate of 1 bass per minute. The bass population structure is currently skewed high due to the limited number of fish under 12 inches in length. The PSD value of 90 is above the typical objective of a PSD index rating of from 40 to 60. In other words, 90% of the Emiquon bass population was over 12 inches in length. The RSD15 value of 71, RSD18 value of 20 and RSD19 value of 6 were also very high. The body condition rating,(Wr), did remain in the very good level at an average of 106 in 2024. The previous 5 years had shown a trend of lower body condition values into the 80’s for the bass from 16 to 19 inches. In 2021 thru 2024 the Largemouth Bass data was much improved for this size group of fish. Overall, the Largemouth Bass population has undergone a substantial decline in density since 2020. The population now appears to be in balance with the current forage and aquatic habitat conditions available in the Emiquon Preserve. The main concern will be the need for stronger year class production and recruitment over the next several years.
White Crappie
Average
The White Crappie population was again sampled at a low density at .16 fish per minute by electrofishing in 2024. But the 2024, spring trap net survey had an improved collection rate of 6.1 fish per net night. This is a consistent density increase for White Crappie from the .42 fish per net night collected in 2019. The size range was from 3.5 to 14.5 inches in length. The body condition average was very good at a Wr of 104. The future emergence of the White Crappie population to a common occurrence will probably depend upon the water clarity. In a lake habitat with both species of crappie, the black crappie tends to dominate in clearer water, while the White Crappie tend to succeed with more turbid conditions. The overall crappie density was reduced in the electrofishing surveys in 2024. This lower density trend is evident in all the Centrarchidae populations in Emiquon in 2024. A dense crappie population with larger fish present, will feed on the gizzard shad population and provide additional predation upon potential exotic and invasive fish species reproduction. The current crappie regulation is a 9-inch minimum size limit and a maximum harvest of 25 fish per day per angler. The goal of this regulation is to maintain a dense crappie population and allow a sustainable high, yearly harvest.
Pumpkinseed
Poor
In 2024 the Pumpkinseed population was sampled by 15 fish by electrofishing. These fish ranged from 2.4 to 6.2 inches in length. The Pumpkinseed electrofishing collection rate for stock size fish (over 3.1 inches) was .07 fish per minute. This continues the rapid population decline over the last 5 years. Our electrofishing effort in the large rip rap in front of the control gate in the main ditch held all the fish sampled in 2024. Dense stands of submerged aquatic vegetation will be a key to allow the current Pumpkinseed population the potential for an improved spawn and recruitment in the future.
Bowfin
Fair
The Bowfin population was sampled by 28 fish in the spring trap net survey and 26 fish in the fall electrofishing surveys. The size ranged from 14.3 to 30.3 inches in length. Several year classes appear to be present. The body condition of many of these fish was average to very poor in 2022 thru 2024. The main forage base and habitat change have resulted in a rapid population density reduction for the Bowfin in the Emiquon Preserve since 2020. The Bowfin population had seen an increase in density and biomass in the sampling up to 2020. In 2020, the fall electrofishing CPUE was .77 fish per minute and 96.5 pounds per hour. The 2021, spring trap net survey had a collection rate of 4.3 fish per net night and 27.3 pounds per net night. In 2024, the spring trap net collection rate was .58 fish per net night and 3.1 pounds of fish per net night, and the electrofishing rate was .12 fish per minute and 30.6 pounds per hour. This is a major reduction in the Bowfin population over the last 5 years for the Emiquon Preserve.
Black Crappie
Average
Black Crappie: The Black Crappie population was sampled by 51 stock sized fish by electrofishing and 274 fish by trap nets in 2024. The Black Crappie electrofishing collection rate was .27 fish per minute for all sizes in 2023. This rate was below the previous 5-year average of 2.2 fish per minute of electrofishing. The Black Crappie population density has shown a consistent decline since 2020. The 2019 trap net CPUE was 17.9 fish per net night and the 2014 collection rate was down to 5.7 fish per net night. The Black Crappie sample shows a low number of fish in the YOY class up to 5.9 inches long and multiple year classes from 7.2 to 14.0 inches long. The body condition was still a good Wr of 96 for the fish over 8 inches.
Bluegill
Average
In 2024 the Bluegill population was sampled by 228 fish by electrofishing. The survey samples represent a Bluegill population with a distribution from 1.2 to 7.4 inches long. The Bluegill recruitment was low again in 2024 with a YAR of .24. The last high recruitment year for Bluegill was in 2019. The body condition remained good with an average Wr of 102 for the fish over 5 inches. The Bluegill electrofishing collection rate for stock size fish (over 3.1 inches) was .86 fish per minute in 2024. This is a continued trend of Bluegill density decrease that started in 2020. 1.8 fish per minute were collected in 2023 and 1.4 fish per minute in 2022. This is a decrease from 2.1 fish per minute in 2021 and from the 3.4 fish per minute collected in 2020. This density trend will be evaluated in the future. The Bluegill PSD value of 26 for electrofishing was close to the objective range of 20 to 40. But it is a decrease from the 49 in 2022. The Bluegill population structure is primarily under 7 inches in length. The Bluegill RSD7 was at 2 which is well below the objective range of 5 to 20, and below the previous 5-year average of 29. The RSD7.5 value of 0 is poor, and is reflected in the low numbers of quality Bluegill that have existed at Emiquon since 2019. The dense areas of submerged aquatic vegetation is the key to allow the current Bluegill population the potential for an excellent spawn and recruitment. These large areas of vegetated habitat would also provide a preferred niche for the Lepomis sp. in competition with the expanding gizzard shad, buffalo and common carp population. However, these vegetation areas have not been present at high levels in the last 5 years. The current Bluegill (Lepomis sp.)regulation is a maximum harvest of 25 fish per day per angler. The main scope of this regulation is to prevent wanton waste by anglers.
Channel Catfish
Very Good
37 Channel Catfish were sampled in 2024 by electrofishing and 124 in trap nets. This continues the upward density trend since their consistent sampling that started in 2014. In 2024, the size ranged from 12.7 to 30.0 inches in length. The body condition was good in 2024 with a Wr value of 91 in the fall electrofishing survey. If turbid water conditions exist in the future, Channel Catfish recruitment should continue at a high level. The current Channel Catfish regulation is a maximum harvest of 6 fish per day per angler. The main scope of this regulation is to prevent wanton waste by anglers.
Yellow Bass
Poor
The Yellow Bass introduction into the Emiquon Preserve has allowed this population to expand rapidly since 2018. The catch per minute rate by electrofishing went up from .49 fish per minute in 2020 to 1.2 fish per minute in 2021 and 1.1 fish per minute in 2022. However, in 2024 the catch rate continued the decline noted in 2023. The catch per minute dropped to .36 fish per minute by electrofishing in 2023, and down to .25 fish per minute in 2024. And the corresponding catch rate per trap net night went from 26.2 in 2021, to 14.5 in 2022, to 12.8 in 2023, and to 4.9 fish per net night. The body condition of the Yellow Bass was also noted by very poor condition in 2023 with a Wr average of 84 and a 2024 average of 92. It is interesting to note that the Yellow Bass population appears to be showing a similar decline as noted with the Bowfin and Centrarchidae populations in Emiquon.
| 2023 | Alligator Gar | Adult | 1007 |
Contact
309-547-2730
Description
Historically, what is now the Emiquon Preserve included two backwater lakes, Thompson Lake and Flag Lake, and was argued to have been one of the better hunting and fishing complexes in the Illinois River Valley if not the whole Midwest. From the early 1920s through the present, most of the property currently owned by the Conservancy was managed for agriculture, most recently primarily for intensive row-crop production. In 2007, the site pumps were shut off and the water level in the site was allowed to rise and reform the lakes. The current Thompson/Flag Lake covers approximately 4,000 surface acres. The lake topography is two large shallow basins with deep water ditches dissecting it. In midsummer, the lake basins can be 70% covered with aquatic vegetation. A concrete boat ramp with a gravel parking lot for 25 vehicle/trailers is present and there is a boardwalk, visitor area and canoe launch.Fishery History
In 2007, The Nature Conservancy entered into a Cooperative Fish Management Agreement with the Illinois Department of Natural Resources for the Emiquon Preserve. The water bodies on the site underwent an immediate fish rehabilitation project to remove exotic fish species. The IDNR initiated fish restocking in 2007 with brood fish that included: Largemouth Bass, White Crappie, Black Crappie, Bluegill, Bowfin, Spotted Gar, Channel Catfish, Brown Bullhead, Warmouth, Orangespotted Sunfish, Pumpkinseed Sunfish, Golden Shiner, Brook Silverside, and Blackstripe Topminnow. IDNR fish stockings and surveys have resulted in the potential of at least 43 fish species now present in the lake. In 2024, the total nonnative fish collected were 53 Common Carp, 7 Silver Carp, 3 Grass Carp and 1 Common Carp x Goldfish Hybrid. These new fish species collections probably entered the Preserve from the Illinois River through the new control structure site. The size of these fish indicate that they arrived through a large passage like the control structure. The Silver Carp, Bighead Carp and the Grass Carp had extremely robust body conditions. Their growth is currently at an accelerated rate in the Preserve. No reproduction and recruitment has been documented at this time for the invasive carp species. The presence of an expanding population of native buffalo species, Common Carp, Grass Carp and Silver Carp is an ominous sign for the future aquatic habitat in the Preserve. The rapid removal of the submerged aquatic plant community through consumption by Grass Carp, and decreased water clarity from algal blooms stimulated by the Silver Carp biomass may soon reach a critical tipping point. Then the reduced water clarity will likely allow the Common Carp to achieve very high reproduction and recruitment in the Preserve. A rapid degradation of the aquatic habitat, submerged aquatic plant community, and native fish population is the factual, proven result from Common Carp density is high.Site Regulations
Public access to the water bodies on the Emiquon Preserve is from sunrise to sunset and is limited to registered boats. Free annual registration to access the site for all users is required and available at the adjacent Dickson Mounds State Museum. Only electric trolling motors are allowed. No gas motors are allowed on boats. Access is year round, except during the Central Zone waterfowl hunting season when no water access is allowed on hunting days. Currently waterfowl hunting is allowed 3 days a week, thereby allowing fishing access 4 days a week. Ice fishing is allowed when practical on the entire lake basin. The site contains an inviolate refuge from public access. This refuge will attempt to serve as a limited disturbance area for all of the wildlife utilizing the Preserve. This refuge encompasses approximately the eastern half of the former Thompson Lake basin, all of the former Flag Lake basin and then to the Illinois River levee. This refuge area is designated with marked buoys and signs.
Site-Specific Fishing Regulations:
- All Fish: 2 pole and line fishing only and each pole must not have more than 2 hooks or lures attached while fishing; bow fishing for carps is allowed
- Bluegill, Redear, Pumpkinseed, Green, Orangespotted, or Hybrid Sunfish: 25 Fish Daily Harvest Limit
- Channel Catfish: 6 Fish Daily Harvest Limit
- Large or Smallmouth Bass: 18 inch Minimum Length Limit; 1 Fish Daily Harvest Limit
- Walleye, Sauger, or Walleye Hybrid: 14 inch Minimum Length Limit; 6 Fish Daily Harvest Limit (statewide regulation)
- White, Black, or Hybrid Crappie: 9 inch Minimum Length Limit; 25 Fish Daily Harvest Limit