The Nature Conservancy's Emiquon Preserve: Fish and Aquatic Vegetation Monitoring

Nerissa N. Michaels, Greg G. Sass

Research output: Book/Report/Conference proceedingTechnical report


Aquatic Vegetation Sampling and Gear Effort –Thompson Lake: We conducted aquatic vegetation sampling from 4/17/2009to 10/14/2009in littoral (>428 feet asl) and pelagic (≤428 feet asl) areas of Thompson Lake. We sampled aquatic vegetation monthly at five littoral and pelagic site seach and at 20 littoral and pelagic sites each during the month of July. Additionally, three east/west fixed site transects were sampled monthly at seven locations along each transect for aquatic vegetation from May-October. Aquatic Vegetation Collected and Observed Species –Thompson Lake: We collected and/or observed 13 aquatic vegetation species (submersed, emergent, and floating-leaved) at 85 out of 100 random littoral and pelagic sites at Thompson Lake in 2009. Community composition of the vegetated sites was dominated by submersed aquatic vegetation including leafy pondweed Potamogeton foliosus and southern naiad Najas guadalupensis (32.2%), American elodea Elodea canadensis (22.5%), coontail Ceratophyllum demersum (19.5%), sago pondweed Stuckenia pectinata (5.3%), brittle naiad Najas minor (4.2%), American pondweed P. nodosus (3.7%), creeping water primrose Jussiaea repens (3.2%), Eurasian water milfoil Myriophyllum spicatum (2.4%), and curlyleaf pondweed P. crispus (2.4%). Emergent aquatic vegetation composition at vegetated random sites was minimal, but included narrow-leaved cattail Typha angustifolia (2.2%). One non-rooted,floating-leaved vegetation family, Lemnaceae, was collected and represented by duckweed spp. comprising 1.9% of the community composition at vegetated sites. Other species,such as American lotus Nelumbo lutea and common arrowhead Sagittaria latifolia,were observed growing in the lake, but were not collected in our samples. Curlyleaf pondweed and Eurasian water milfoil were the only non-native species of aquatic vegetation observed. Fish Sampling and Gear Effort-Thompson Lake: We conducted monthly fish sampling on Thompson Lake from 4/20/09-10/8/09 using a multiple gear approach. Sampling consisted of 28 electrofishing runs (15 minutes each), 28 fyke net sets (24 hours each), and 28 mini-fyke net sets (24 hours each) at shoreline or pseudo-shoreline (used for shoreline gear) sites. Additionally, seven tandem fyke net sets (24 hours each) and seven tandem mini-fyke net sets (24 hours each) were deployed at open water sites. All gears were fished according to the protocols of Gutreuter et al. (1995), which are used for the Long Term Resource Monitoring Program. Total Fish Catch-Thompson Lake: We collected a total of 9,860 fish representing 15 species and 8 families from Thompson Lake in 2009. Overall, catches were dominated by centrarchids (mainly bluegill Lepomis macrochirus and young-of-year Lepomis spp). Bluegill 40 mm dominated the catch with 4,552 fish comprising 46.1% of the total catch. Unidentified Lepomis spp. (bluegill L. macrochirusor pumpkinseed L. gibbosus with lengths <40 mm) followed with 1,967 fish at 20.1% of the total catch, and black crappie Pomoxis nigromaculatus with 1,535 fish at 15.6% of the total catch. Largemouth bass Micropterus salmoides (824, 8.4%), pumpkinseed L. gibbosus (771, 7.8%), common carp Cyprinus carpio (58, 0.6%), unidentified Ameiurus spp. (bullhead catfish spp.) (40, 0.4%), warmouth L. gulosus (31, 0.3%), black bullhead A. melas (29, 0.3%), bowfin Amia calva (13, 0.1%), western mosquitofish Gambusia affinis (10, 0.1%), greensunfish L. cyanellus (7, 0.1%), green sunfish x pumpkinseed hybrid L. cyanellus x L. gibbosus (7, 0.1%), brown bullhead Ameiurus nebulosus (6, 0.1%), gizzard shad Dorosoma cepedianum (5, 0.1%), spotted gar L. oculatus (3, <0.1%), goldfish Carassius auratus,and lake chubsucker Erimyzon sucetta (1, <0.1%)made up the remainder of the catch. Common carp and goldfish were the only non-native species collected. Undesirable fish species that either survived the rotenone or were unintentionally stocked into Thompson Lake include gizzard shad, black bullhead, green sunfish, western mosquitofish, and green sunfish x pumpkinseed hybrid. Catch-per-Unit Effort (CPUE)-Thompson Lake: We collected 10 fish species while electrofishing Thompson Lake in 2009, which comprised 6.5% of the total catch by all gears. Largemouth bass dominated the catch with 56fish/hour of electrofishing, followed by 16 bluegill(40 mm) per hour, 7 unidentified Lepomis spp.(bluegill or pumpkinseed <40 mm) and black crappie per hour, 3pumpkinseed(40 mm)per hour, 1 bowfin and common carp per hour,and <1 gizzard shad, green sunfish, mosquitofish,and spotted gar per hour electrofishing. Catch rates of different fish species varied by gear, but largemouth bass, black crappie, bluegill, pumpkinseed and unidentified Lepomis spp. (bluegill or pumpkinseed <40 mm) dominated the catch by all gears. Common carp and goldfish were the only invasive fish species collected while electrofishing and gizzard shad, green sunfish, and western mosquitofish were the only undesirable fish species collected while electrofishing.
Original languageEnglish (US)
PublisherIllinois Natural History Survey
StatePublished - Jan 15 2010

Publication series

NameINHS Technical Report 2010 (14)


  • INHS


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