Introduction

Center for Aquatic Ecology

Center for Biodiversity

Center for Economic Entomology

Center for Wildlife Ecology

Financial Statement

Publications of the Staff

Credits

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CENTER FOR AQUATIC ECOLOGY

David Philipp, Director

The aquatic resources of Illinois range from streams and ponds to impoundments to a major floodplain river (the Mississippi) and one of the Great Lakes (Michigan). The mission of the Center for Aquatic Ecology is to conduct basic and applied research on the state's aquatic ecosystems and to investigate the biology of the associated flora and fauna. The Illinois Natural History Survey has employed respected and competent aquatic researchers since its inception under the direction of Stephen A. Forbes. The present Center staff is composed of nationally and internationally recognized scientists working in concert with a talented and dedicated support staff to conduct quality research that provides information for enlightened management and conservation of aquatic resources.

From its Champaign headquarters, the Center for Aquatic Ecology maintains six permanent field stations: the Aquatic Research Field Laboratory in Champaign ("the ponds"), the Sam Parr Biological Station at Kinmundy, the Ridge Lake Station near Charleston, the Lake Michigan Biological Station at Zion, the Kaskaskia Biological Station at Lake Shelbyville, and the River Research Laboratory at the Stephen A. Forbes Biological Station in Havana. In addition, two field stations have been established on the Upper Mississippi and Illinois rivers as components of a network of six stations operated by five states and the U.S. Fish and Wildlife Service to collect and analyze data on fish populations, vegetation, and water quality for the Long-Term Resource Monitoring Program (LTRM). This important system of field stations allows Center scientists to conduct valuable field research at sites that reflect the diversity within Illinois.

Public Service

Center scientists disseminated their findings by making scientific presentations to a wide-ranging audience, participating in formal university education programs by advising graduate students and teaching courses, identifying aquatic organisms for the public, serving on a variety of state and federal technical committees and advisory boards, and serving professional societies and organizations as officers and members of committees. They actively presented their research findings, including 4 invited formal seminars at major research universities and 42 scientific presentations delivered at professional meetings -- 22 at the state/regional level, 9 at the national level, and 11 internationally.

While dissemination of research findings to professional audiences is a primary activity, Center scientific staff also recognize the importance of providing information directly to the citizens of Illinois. They presented eight talks to local groups, nature clubs, and fishing organizations, and were interviewed for four radio programs, six TV programs, seven magazine articles, and one feature film. Center scientists were active in reviewing manuscripts submitted to national and international journals and proposals submitted to state and national funding agencies. They also served as editors for several scientific journals, including Transactions of the American Fisheries Society, North American Journal of Fisheries Management, Oecologia, Energy, Ecological Economics, and The Macroscope. In addition, staff members were active in many professional organizations, including the planning of various conferences. These organizations included the American Fisheries Society, the North American Benthological Society, the Ecological Society of America, the Society for Environmental Toxicology and Contamination, the Society of Ichthyologists and Herpetologists, the International Society for Ecological Modeling, the International Society for Ecological Economics, and the Illinois Lake Management Association. Dr. David P. Philipp continues as president of the North Central Division of the American Fisheries Society. A new colleague, Dr. William J. Resetarits, co-organized the symposium "The State of Experimental Ecology: Questions, Levels, and Approaches" at the 1994 annual meeting of the American Society of Zoologists.

Center scientists actively participate in graduate education, teaching 2 courses this year and advising 5 postdoctoral associates, 5 doctoral students, and 20 master's candidates. Every professional scientist in the Center for Aquatic Ecology is affiliated with at least one academic department. At the University of Illinois these include Ecology, Ethology and Evolution; Animal Sciences; Urban and Regional Planning; Forestry; the National Center for Supercomputing Applications; and the Institute for Environmental Studies. Staff are also affiliated with Loyola University, Northwestern University, and Eastern Illinois University. Center scientists also work with graduate students attending Loyola, Purdue, Southern Illinois, Eastern Illinois, Western Illinois, and Northwestern universities. Center scientists, especially Dr. David H. Wahl, have been instrumental in establishing an interdisciplinary program in Natural Resources Ecology and Conservation Biology in the newly reorganized College of Agriculture at the University of Illinois. These activities provide the opportunity for Center staff to pass their skills and knowledge to another generation of researchers and resource managers.

Center staff's appointments to state and national technical advisory committees reflect recognition of accomplishments. Dr. Richard E. Sparks, Director of the River Research Laboratory at the Forbes Biological Station, is on the Liaison Committee to the U.S. Geological Survey's National Water Quality Assessment Program for the Illinois River. He also served on the Water Science and Technology Board, National Research Council of the National Academy of Sciences, providing advice on using a watershed approach to sustainable development. In addition, Dr. Sparks serves on the Midwest Advisory Team of the President's Council on Sustainable Development. Drs. Daniel W. Schneider, Daniel A. Soluk, and Sparks have served on the organizing committees of the last two Governor's Biennial Conferences on the Illinois River. Dr. David P. Philipp continues service on two advisory review teams of the Bureau of Land Management, one for the endangered Gila River complex and one on the Endangered Species Recovery Panel for the Colorado River. Dr. J. Ellen Marsden served on the Great Lakes Panel on Non-indigenous Nuisance Species of the Great Lakes Commission. Mr. K. Douglas Blodgett served on the U.S. Geological Society Lower Illinois River National Water Quality Assessment Program (NAWQA) Liaison Committee. Dr. David Wahl continues to serve on the Illinois Aquaculture Advisory Committee of the Illinois Department of Conservation, a group designed to develop and enforce regulations pertaining to the importation of non-native aquatic organisms into Illinois.

The Flood of 1993 on the Mississippi and Illinois rivers has resulted in additional, continuing opportunities for Center aquatic ecologists. Dr. Richard Sparks cochaired and Dr. Daniel Schneider served on the Economic and Ecological Advisory Panel for the Lieutenant Governor's Conference on the Illinois River. Dr. Sparks has coorganized a symposium on extreme hydrological events at the 1995 meeting of the Ecological Society of America. In addition, Dr. Sparks attended a congressional Capitol Hill briefing on sustainable redevelopment, addressing questions of long-term strategies to cope with rivers that sometimes reach flood stage. Mr. Charles H. Theiling served on the Interagency Floodplain Research Committee-Scientific and Assessment and Strategy Team (ecology group).

Following the publication of the Critical Trends Assessment Project Report, Drs. Steven Kohler, Daniel Soluk, and Richard Sparks have advised and supervised the River Watch project, in which various citizens' groups collect important environmental data and, hence, contribute personally to monitoring environmental quality.

A number of Center staff testified as expert witnesses during a variety of agency hearings. Center staff provided recommendations on comprehensive lake and watershed management to private lake homeowners and personnel managing the private and public waters in Illinois. Dr. David Philipp's genetics laboratory continued certification or denial of potential state and world record fish. Dr. J. Ellen Marsden and the staff at the Lake Michigan Biological Station, together with Dr. Richard Sparks and his staff on the Illinois and Mississippi rivers, continue to monitor the spread of zebra mussels and provide assistance on control and assessment.

Special Recognition

Center for Aquatic Ecology scientists continue to be successful in obtaining research funding, with every professional scientist being awarded a major research grant or contract from a state or federal agency. The sources of these funds were diverse and include the National Science Foundation, the National Biological Survey, the National Institutes of Health, the U.S. Fish and Wildlife Service, the U.S. Department of Energy, the U.S. and Illinois Environmental Protection Agencies, the U.S. Army Corps of Engineers, the Illinois Department of Conservation, the Illinois Department of Natural Resources, and the Illinois-Indiana Sea Grant Program.

The Center for Aquatic Ecology is particularly proud of its part in responding to three recent challenges/opportunities mentioned above: the introduction and rapid proliferation of the zebra mussel, the Illinois Critical Trends Project and its follow-up, and the Flood of 1993 and its consequences. Our efforts in these areas have been shared by the entire Center. In addition to basic and applied scientific activities, Center staff have contributed to synthesizing information at many spatial scales up to that of the ecosystem level, and to public discussions of how to respond. Maintaining that mix of efforts will be a continuing goal for us.

Research Reports

The summaries that follow indicate the scope and significance of research undertaken by the staff of the Center for Aquatic Ecology.

Database for stream fishes
P. Bayley (Oregon State University) , R. Illyes, S. Sobaski
The stream fisheries manager needs to maintain or enhance the resource. The primary constraint to productive and attractive stream fisheries in Illinois is the environment, including the physical habitat as well as the biota that interact with fish species of interest. In order to plan conservation, restoration, and other management-related projects, the Survey and the Illinois Department of Conservation have established a statewide stream fisheries database. It summarizes fish sample and stream habitat data collected by both agencies since the early 1950s and will be expanded by future surveys and studies.

Walleye and gizzard shad populations
T. Galarowicz, R. Herendeen, D. Wahl
Several processes that determine a larval fish's first-summer survival and growth are known to be size-dependent, such as susceptibility to predation. Predicting the numbers and condition of surviving juveniles, therefore, requires a highly disaggregated modeling approach that keeps track of many different size classes. Survey researchers are building such an individual-based model to better predict the consequences of management options on populations, calibrating it with results from laboratory and field experiments at the Kaskaskia Field Station.

Natural capital of Illinois
R. Herendeen, C. Sun
In the Illinois Critical Environmental Trends Assessment Project, Survey researchers evaluated in physical terms the net accumulation of many nonrenewable and renewable resources in Illinois, including fossil fuels, timber, and soil. Researchers are now evaluating these changes in economic terms as a correction to the gross state product (GSP). GSP is a measure of income that is corrected for loss or gain in wealth that made that income possible, thus presenting a better picture of how well off Illinois is. For example, estimates of coal reserves increased in the period 1966-1981, leading to a positive correction to GSP. Today, coal is being slowly depleted, leading to a negative correction.

Estimating fish abundance
R. Herendeen, P. Bayley (Oregon State University)
Size (and hence age) distribution of fish shows their reproductive health. Determining the distribution from net-capture data is subject to bias because of larger fishes' ability to evade the research net. Survey researchers have explicitly modeled the size-dependent evasion process during the setting out of a purse seine. This allows researchers to convert the observed size distribution in the purse seine to the actual distribution. Model results agree qualitatively with observation. Researchers continue to calibrate the model with field data derived from a larger, impenetrable block net, which is used to determine what fish are actually present.

Trophic interactions in ecosystems
R. Herendeen
Trophic cascade and bottom-up:top-down hypotheses are used in this study to describe and predict how perturbing one organism affects others in an ecosystem. Initial evidence from aquatic systems has recently been supplemented with terrestrial examples. From this research a quantitative general theory has been developed that predicts all features of trophic cascades and top-down:bottom-up effects, and covers intermediate cases as well. Specific quantitative predictions agree with known results from the Lotka-Volterra theory of predator-prey relations. This more general approach is applicable to food webs as well as to chains and to a wide range of interactions between organisms.

Energy analysis versus EMERGY analysis
R. Herendeen, M. Brown (University of Florida)
One useful environmental quality indicator is to determine total energy requirements, arguing that energy is a good surrogate for environmental burden. The accounting scheme of energy analysis is relatively rigorous and well-publicized; it does not, however, quantify the environment's role in absorbing, processing, and neutralizing pollution and environmental impacts. EMERGY analysis attempts this more comprehensive accounting, but its accounting scheme has been unavailable in open literature. Survey researchers have completed a detailed comparison of these two environmental accounting schemes for internal consistency, agreement with existing science, and usefulness.

Mainstream channel fauna of large rivers
D. Soluk, R. Sparks, S. Kohler
The mainstream channels of rivers, dominated by loosely consolidated sandy sediments, are generally considered to be a hostile habitat for benthic fauna. Studies, however, have revealed that there are many organisms living in and on these sediments. Little is known about these communities and their importance to river ecosystems, and still less is known about the effects on them from human activities and channel modifications. Research in the upper Mississippi and Illinois rivers is focusing on how mainstream channel fauna are affected by silt-loading from agriculture and modification of the channel to facilitate navigation.

Sedimentation and stream communities
S. Kohler, P. Bayley (Oregon State University), D. Soluk
Land-use practices in watersheds can strongly affect the integrity of stream communities. Army training at Fort Bragg, North Carolina, has involved extensive manipulation of sandhills landscape. This has produced pronounced increases in soil erosion locally and, in some cases, over extensive areas within some watersheds. Survey researchers are investigating how and to what extent physical habitat characteristics of Fort Bragg streams and their fish and benthic invertebrate communities are affected by increased sedimentation, using unimpacted streams as controls. Research results should lead to more effective means of monitoring stream integrity in this region and in Illinois.

Structure of stream food webs
S. Kohler, M. Wiley (University of Michigan)
The resilience of ecosystems to major perturbations and the mechanisms determining the biodiversity of communities are fundamental issues in basic and applied ecology. The removal of a dominant competitor from streams over a broad geographic area by a parasitic infection has provided researchers with a unique opportunity to address these issues in otherwise relatively unperturbed systems. Research focuses on how the dominant competitor affects community organization and energy flow, and how the system responds to the competitor's removal and, perhaps, to its eventual recovery to preinfection levels.

Host-parasite relationships in streams
S. Kohler, M. Wiley (University of Michigan)
The role of parasites and pathogens in the population dynamics of stream invertebrates has received little study. A microsporidian parasite has been associated with the collapse of populations of a dominant insect herbivore in streams over a broad geographic area. Simulation models suggest that populations of the insect will not recover to precollapse levels and will exhibit regular cycles with peak densities less than one-tenth of historical levels. Researchers are attempting to verify these predictions and to assess the generality of such interactions.

Upstream movements of invertebrates
D. Soluk, S. Kohler
Knowledge of movement patterns and dispersal mechanisms is needed to understand the dynamics of natural populations and to predict the recovery of communities from the effects of natural or human disturbance. Research on dispersal in streams has focused mostly on drift and predicts that over the season, upstream areas should be depleted of organisms. Lack of evidence of depletion is explained as a function of recruitment from other areas. An alternative explanation is that organisms may simply travel upstream after drifting downstream for some time. Using innovative technology, researchers are measuring upstream movement and colonization under natural conditions.

Long-term changes in insect communities
S. Kohler, D. Soluk
Data on long-term trends for insect populations in Illinois streams are generally lacking. This is unfortunate because aquatic insects are often excellent indicators of stream quality. Researchers are revisiting a number of streams in the state that were intensively studied by Survey taxonomists in the first half of the century, and for which the mayfly and caddisfly faunas present during that period are quite well known. Because these groups are sensitive to changes in environmental quality, this study should help to determine if and how the integrity of these streams has changed over the past 40-50 years.

Invertebrates in floodplain ponds
D. Corti, S. Kohler, R. Sparks
Management of Mississippi River water levels greatly affect the river's floodplain wetlands, which provide habitat for ducks, fish, and invertebrates. Flooding interacts with local topography to produce floodplain ponds that vary widely in permanence. Experiments conducted by Survey researchers indicate that both pond permanence and predation by fish and waterfowl strongly affect invertebrate communities in floodplain ponds. Both of these factors appear to contribute to the high diversity of invertebrates observed over large spatial scales in river floodplain systems.

Stream habitat assessment using sonar
R. Illyes, S. Kohler, P. Bayley (Oregon State University
Assessment of instream physical habitat is often used in conjunction with fish and invertebrate surveys to identify mechanisms responsible for changes in biotic integrity. Such assessments are frequently time-consuming and are difficult to perform in many habitats (e.g., deep or highly turbid areas). Survey researchers are attempting to develop a sonar-based device that will allow rapid and effective quantification of major stream-bottom features under a wide range of physical conditions. Data collected by the device will be downloaded to a computer for storage and analysis.

Sport fishing in Lake Michigan
W. Brofka, J.E. Marsden
Sport fishing in the Illinois waters of Lake Michigan was surveyed from April through November using a creel survey. Data collected from anglers included fishing activity, fish harvest, and monetary expenditures. Samples of creeled fish were measured and weighed. Catches for most species decreased compared to 1993 except for coho salmon, which increased, and lake trout, which remained the same. The yellow perch harvest was reduced over 50% from 1993, reflecting a severe decline in the population. Estimated expenditures related to fishing were $1.5 million, down 50% from 1993. The yield value of the sport fishing harvest was approximately $2.07 million.

Otolith and scale methods for aging perch
S. Robillard, J.E. Marsden
The age structure of the yellow perch (Perca flavescens) population in Lake Michigan is assessed annually by five management agencies that each use different structures for aging. The reliability of the most commonly used structures, scales, has not been formally evaluated for this population. Survey scientists compared three readers' scale and sagittal otolith ages of 150 yellow perch from southwestern Lake Michigan. Otoliths had better precision (reproducibility), readability, and more recognizable annuli over all ages sampled than scales. Scale ages disagreed with otolith ages when those ages were greater than 7; that is, fish usually were aged younger by scales.

Yellow perch population assessment
S. Robillard, J.E. Marsden
Yellow perch population monitoring has indicated that a strong year class has not been produced since 1988. To improve the understanding of assessment gear capture success, researchers are comparing Illinois Department of Conservation (IDOC) graded mesh gill nets used for spawning assessment to Survey fyke nets. Previous tagging data have suggested that yellow perch return to the same spawning grounds each year. Adult yellow perch were collected at sites near an IDOC index station with fyke nets to show whether these spawning concentrations occur and, if they do, where they are focused relative to the station. Subsamples of fish were aged to describe the age distribution of the population.

Yellow perch early life history
S. Robillard, T. Kassler, J.E. Marsden
The yellow perch population in Lake Michigan is undergoing a severe decline due to a recruitment failure between the larval and young-of-the-year stages. Larval yellow perch migrate vertically in the water column in response to light levels, presumably to maximize access to food, avoid predation, and maintain thermal equilibrium. Survey scientists are sampling larval perch at different depths to assess their abundance and diel distribution. Researchers are also sampling zooplankton to determine whether the food supply of larval perch has changed dramatically since the onset of the population decline.

Reproductive success of lake trout
J.E. Marsden, B. May (Cornell University)
Several genetic strains of lake trout have been stocked into Lake Michigan as part of an effort to restore self-sustaining populations of trout. In 1994, large numbers of naturally spawned eggs were collected from a breakwall in the southern end of the lake. Using genetic and analytical techniques established during similar work in Lake Ontario, researchers will determine which of the stocked strains produced these eggs. Information about which strains reproduce successfully can be used by management agencies to guide stocking strategies.

Lake trout reproduction in Lake Michigan
M. Chotkowski, J.E. Marsden
Stocked lake trout have failed to reproduce successfully in Lake Michigan and the other Great Lakes. In previous years, Survey researchers found evidence that more spawning occurs on man-made structures (breakwalls) than on natural reefs, but fry survival appears to be extremely low. Researchers are examining factors that may affect egg and fry survival, focusing on the effect of predation by native and introduced fish species: sculpins, gobies, carp, and alewife.

Round gobies in Lake Michigan
M. Chotkowski, J.E. Marsden
The round goby, Neogobius melanostomus, was recently introduced into the Great Lakes. Although it occupies only a small range in southern Lake Michigan, there is concern that as it proliferates it will displace native cottids and impede the rehabilitation of lake trout populations. Survey researchers have determined that gobies will eat lake trout eggs and fry and that substrate composition and egg/fry developmental stage affect consumption rates. Researchers are developing a functional comparison of round gobies and mottled sculpins (Cottus bairdi) as benthic predators to predict consequences of the round goby invasion and to develop strategies to maximize lake trout reproductive success in their presence.

Impact of zebra mussels on gastropods
T. Keniry, J. Stein, D. Padilla (University of Wisconsin-Madison), J.E. Marsden, D. Schneider, C. Elderkin (Western Illinois University)
Zebra mussels are widely known to harm native unionids by colonizing their shells; they are also likely to adversely affect other hard-shelled species, such as snails and crayfish. In laboratory experiments researchers are examining the effects of zebra mussel fouling on snail fecundity (egg production), feeding rates (fecal pellet production), and growth. Researchers are also quantifying the rates of infestation of zebra mussels on different snail species in the field, and attempting to correlate infestation rates with snail habitat and morphology.

Zebra mussel light-dark preferences
T. Keniry, G. Freysinger, E. Sheehan, J.E. Marsden
Zebra mussels appear to avoid sunlit areas, which may be due to adverse effects of ultraviolet light, or use of sunlight as a cue that the mussel is in an exposed area and may be vulnerable to predation. In laboratory experiments, mussels placed at the boundary between light and dark areas tended to move into the dark area; mussels placed in a dark field moved less than mussels placed in a light field. Survey researchers are examining whether the density of shell coloration affects sensitivity to light, as demonstrated by response to light. Light may be a potential tool to dissuade mussels from settling on vulnerable structures, such as intake pipes.

Factors affecting bass recruitment
M. Fuhr, D. Philipp
Largemouth bass populations have had recruitment problems for years in several northern Illinois impoundments. Although adult bass successfully reproduce, few offspring survive to reach catchable size. To determine what factors are playing major roles, seven study lakes with various degrees of recruitment success have been compared and monitored for the duration and success of spawning, as well as for relative growth and overwinter survival of offspring. Results suggest that factors affecting year-class strength during the first summer, not survival over the first winter, are most important in these systems.

Reproductive success in bass
D. Philipp, M. Kubacki (Arizona Game and Fish), A. Toline, F. Phelan and H. Ferguson (Queen's University Biological Station)
Male largemouth and smallmouth bass build nests in lake or stream substrates, court and spawn with females, and then remain to protect their brood, providing parental care for up to four to six weeks after fertilization of the eggs. To determine how reproductive success varies among years, researchers have been intensively monitoring the spawning success as well as the duration of nesting and parental care behavior in both species for the past six years. Four distinct habitats in southern Ontario are being compared as well to determine the spatial and temporal differences among populations.

Spawning dynamics of a bass population
A. Toline, D. Philipp, F. Phelan (Queen's University Biological Station)
The spawning histories (location, date, mating success, and reproductive success) of all male smallmouth bass in a 1.5 km section of a stream in southern Ontario have been monitored for the past three years. From individual mark and recapture data, preliminary results indicate that successful males return to previous spawning sites (within 3-4 m) in following years, whereas unsuccessful males may move up or downstream several pools (up to 0.5 km). Determining which factors affect individual variation in male reproductive success will help develop better management programs for this species.

Catch-and-release angling in bass
D. Philipp, M. Kubacki (Arizona Game and Fish), D.B.F. Philipp, F. Phelan (Queen's University Biological Station)
Both largemouth and smallmouth bass are highly prized sportfish, and many are captured in the spring when males are sitting on nests providing parental care for their young. Little is known about how catch-and-release angling affects the reproductive success of nesting bass. Data are being collected from captured-and-released bass: male size, brood developmental stage, egg score, return time, and predation rates. This information will be used to determine how catch-and-release angling impacts the reproductive success of both species and how those impacts can be minimized.

Spawning dynamics of bluegill
J. Claussen, D. Philipp
Bluegill have highly social reproductive behaviors in which some males build nests in colonies, court and spawn with females, and provide all parental care for the young in the nest. This study monitors annual variation in the number of males that build nests, spawn, and successfully raise a brood off the nest in a study area of Lake Opinicon, Ontario. Yearly comparisons determine how environmental changes, such as temperature, affect variation in the number of breeding males and females as well as how changes in the overall breeding population affect clutch size. These data provide information for modeling bluegill population dynamics in the Midwest and will aid in management programs.

Interspecific hybridization and cuckoldry
B. Konkle, D. Philipp
Bluegill and pumpkinseed are two species of sunfish that readily hybridize. Researchers are studying these hybridization events in Lake Opinicon, Ontario, to determine how and why they occur. These two species also exhibit alternative reproductive strategies, including the use of cuckoldry. Using behavioral observation and underwater videos, researchers discovered that spawning pairs of pumpkinseed were being parasitized by cuckolder male bluegill. Molecular techniques confirmed that, in fact, all natural interspecific hybrids were the result of matings of pumpkinseed females and bluegill males. Current research attempts to determine the evolutionary significance of these events.

Developmental genetics of sunfish hybrids
R. Fields, M. Fields, J. Claussen, D. Philipp, J. Epifanio (Michigan State University)
Among the sunfishes, hybridization between species is a common event. This work studies the pattern of gene expression during the various stages of embryonic and larval development of hybrids. Bluegill, pumpkinseed, and their hybrids were collected and gametes from each were extracted and used for in vitro fertilizations to make F1 hybrids as well as the backcrosses of each species. Embryos were raised and sampled at various developmental stages. Using molecular techniques, researchers are determining when certain genes turn on during development and the patterns of inheritance of nuclear DNA markers.

Local adaptation in largemouth bass
D. Philipp, J. Claussen
When foreign genes are introduced into a native population and interbreeding occurs among individuals, the genetic makeup of that population is disrupted, a change that often has negative effects. To assess these potential negative impacts, researchers conducted a series of experiments to compare survival, growth, and reproductive success of genetically defined stocks of largemouth bass in different geographic habitats. In all experiments survival, growth, and reproductive success of the local stocks were superior to those of the introduced stocks. In addition, extensive introgression among stocks occurred within a very few generations and the performance of introgressed individuals was poorer than in the pure local stock.

Reproductive strategies in bluegill
D. Philipp, J. Claussen, M. Gross (University of Toronto), M. Jennings (Wisconsin Department of Natural Resources), D. Pereira (Minnesota Department of Natural Resources)
Male bluegill exhibit two mutually exclusive alternative reproductive strategies. In the first parental strategy, males delay maturation, build nests in colonies, court and spawn with females, and show parental care. In the second, cuckoldry, males mature at a much younger age and smaller size and "steal" fertilizations from spawning parental males by sneaking into their nests or by mimicking females. A genetic basis for the alternative strategies has been demonstrated by selective breeding techniques. Molecular genetic techniques have also documented successful fertilizations by cuckolder males in the nests of parental males.

Hormones and fish reproductive behavior
D. Philipp, C. Morrey (Hawaii Institute of Marine Biology), J. Claussen, J. Bahr (University of Illinois)
Bluegill exhibit many distinct physical and behavioral traits when they are reproductively active. By measuring hormonal concentrations, particularly 11-ketotestosterone, during bouts of bluegill reproductive activity, researchers can relate them to male reproductive traits and male reproductive success. Blood samples have been analyzed for their hormonal concentrations using radio-immunoassay procedures. Hormone levels are being compared to reproductive activities, such as nest construction, nest position within the colony, male body size, clutch size, and reproductive success.

<Vulnerability of largemouth bass to angling
D. Philipp, J. Claussen, A. Toline, D. Burkett (U.S. Fish and Wildlife Service), J. Koppelman (Missouri Department of Conservation)
Little is known about the long-term effects of angling harvest on sportfish populations. Research has demonstrated that individual largemouth bass are not equally vulnerable to anglers' efforts. In an experimental population exposed only to catch-and-release fishing, certain bass were never caught, whereas others were captured several times. A selective breeding experiment has further demonstrated that hook-and-line vulnerability is heritable. Researchers are now studying the long-term impacts that heavy angler harvest can have on native largemouth bass populations.

Genetic Analysis of Sportfish Populations
R. Fields, M. Desjardins, T. Kassler, J. Ludden, M. Hudson, V. Tranquili, A. Toline, D. Philipp
The stock concept states that species of fish are composed of genetically distinct populations uniquely adapted to their environments. To identify individual stocks of key sportfishes, researchers are analyzing populations of 12 species of fish from distinct watersheds in Minnesota, Wisconsin, and Illinois. Three molecular genetic techniques--protein electrophoresis, RFLP analysis of mitochondrial DNA, and RAPD DNA analysis--are being used to assess the genetic variation present within and among populations of each species. That variation will help determine the genetic structure of populations and define biologically relevant management units.

Genetic analysis of muskellunge
M. Desjardins, R. Fields, D. Wahl, D. Philipp, M. Jennings (Wisconsin Department of Natural Resources)
The muskellunge supports an economically important sport fishery in many north-central states and Canadian provinces. Extensive stocking has become increasingly important to the maintenance of the fishery. Researchers have identified variable protein and DNA markers and are using those markers to describe the genetic variation of native populations of muskellunge. The resulting description of muskellunge stock structure will allow a review of previous stocking programs as well as the development of an efficient and conservative stocking policy.

Genetic analysis of lake herring
R. Fields, M. Fields, J. Pitrak, D. Philipp
Lake herring are an important commercial fishery in Lake Superior. A current management concern is that distinct genetic stocks may exist within the lake, and that some of these stocks may be subjected to overharvest. Researchers are conducting a genetic study of protein and DNA variation to determine the most appropriate method for description of genetic stocks. Newly identified genetic markers are being used to infer stock structure and to assess the need for separate management plans for each breeding population.

Genetic variation in pumpkinseed
D. Philipp, J. Claussen, M. Fox (Trent University, Ontario)
Through natural selection or genetic drift, populations of a given species that have been separated over time may exhibit life history differences. Through the use of molecular genetic techniques, researchers have been assessing genetic differences of various populations of pumpkinseed in three major watersheds in Ontario. Differences among the watersheds are being compared to life history characteristics of each of the study populations.

Amphibian species diversity
W. Resetarits, J. Fauth (College of Charleston)
An important goal of ecology is to identify and understand the processes that generate and maintain species diversity. Understanding these processes is also critical to the preservation of biodiversity. This study focuses on processes affecting frog species diversity in seasonal wetlands in the Sandhills and Coastal Plain regions of the Southeast. These natural wetlands support the most diverse local assemblages of frogs outside the tropics. Experiments in artificial ponds, field sampling, and field experiments are being combined to develop and test an explanatory model of frog species diversity in these seasonal wetlands.

Oviposition site choice
W. Resetarits
Many processes may affect the structure and species composition of aquatic communities. One of the least understood is the role of oviposition site choice in the colonization of aquatic habitats. A large component of the fauna in many aquatic systems is the result of repeated colonization by aquatic insects and amphibians; thus, selectivity by ovipositing females has the potential to dramatically affect the structure and function of aquatic communities. Both experimental studies and mathematical modeling are being used to study the role of oviposition site choice in aquatic systems.

Brook trout-spring salamander interactions
W. Resetarits
The coexistence of stream-dwelling salamanders with predatory fish is a perplexing situation in light of the almost total exclusion of pond-dwelling salamanders by predatory fish. This project focuses on interactions between spring salamanders and brook trout to determine specific factors that contribute to the maintenance and dynamics of spring salamander populations in streams containing brook trout, and to use this as a model system for studying complex mechanisms of species coexistence under asymmetric competition.

Risk analysis of zebra mussel effects
D. Schneider, C. Ellis, K. Cummings, R. Sparks
Survey researchers are using data on boat traffic in Illinois lakes and rivers to develop a probabilistic model of zebra mussel spread in Illinois. This information will be coupled in a geographic information system with collections records of native mussels to predict communities of mussels that are most threatened by the zebra mussel.

Modeling of zebra mussel populations
D. Schneider, S. Aggarwal, J. Stoeckel,
R. Sparks, B. Hannon
Populations of zebra mussels in the Illinois River may be maintained in the face of suboptimal conditions by continued immigration from Lake Michigan. Survey researchers are developing a metapopulation model of the zebra mussel in the Illinois River based on immigration of larvae from Lake Michigan to predict the variability of mussel populations in the river and to search for opportunities for control.

Zebra mussel growth in the Illinois River
D. Schneider, R. Sparks, J. Stoeckel, S. Madon
Survey scientists are measuring growth of individually marked zebra mussels in various habitats in the Illinois River floodplain ecosystem to evaluate the role of temperature, sediment, and body size on zebra mussel growth. Measured growth rates will be used to calibrate an energetic model.

Sediment effects on zebra mussels
D. Schneider, R. Sparks, J. Stoeckel, S. Madon
Researchers are evaluating the effects of natural and artificial suspended sediment on the energetics budget of the zebra mussel. These data will be used to develop a predictive model of zebra mussel growth in turbid river ecosystems.

Resource conflict in levee districts
D. Schneider
The floodplain of the Illinois River has been contested terrain since the nineteenth century as various interests on the river--farmers, commercial hunters and fishermen, private hunting clubs, levee districts, and state agencies, including the Natural History Survey--struggled to control or protect the natural resources of the river. This project investigates the history of the resource conflict and how the struggle at the turn of the century continues to affect the current ecology of the floodplain and its potential for restoration.

Illinois RiverWatch Network
D. Stoeckel, R. Sparks
The Illinois RiverWatch Network, established in 1993 under an initiative of Lieutenant Governor Bob Kustra, is a partnership of Illinois citizens to monitor, restore, and protect the state's rivers and streams. As citizen- scientists, RiverWatch volunteers conduct stream habitat and macroinvertebrate community assessments on an annual basis. Stream assessment protocols conducted by citizen-scientists were developed with technical advice from state agencies interested in obtaining stream-quality data. Data obtained from the citizen-scientist program will be posted to an electronic bulletin board, EcoForum. These data will be used by scientists to gauge long-term trends in Illinois streams.

Determining zebra mussel metabolic rates
S. Madon, D. Schneider, J. Stoeckel, R. Sparks
Measurements of metabolic rate are vital to studies on energetics and functional responses of zebra mussels to environmental variables. However, laboratory estimates of metabolic rate often fail to reflect metabolic costs in natural systems. The electron transport system (ETS) enzyme assay provides a method for measuring metabolic rates in zebra mussels in rivers. Zebra mussel respiration has been calibrated with ETS activity in the laboratory. Survey scientists employ this technique to determine metabolic rates and oxygen demand of zebra mussel populations in the Illinois River.

Zebra mussel veligers in the Illinois River
J. Stoeckel, L. Camlin, D. Blodgett, R. Sparks
The adult zebra mussel population in a particular stretch of a river is dependent upon the production and drifting rates of larvae (veligers) spawned by upstream adults. Results from 1994 indicate that veligers travel down the Illinois River in distinct pulses of similar-sized individuals. These pulses should result in highly localized settling in downstream stretches of the river, with some stretches receiving heavy recruitment and others receiving virtually no recruitment in a given year. The results of this study are being used to aid in the development of a population model and management plan for zebra mussels in the Illinois River.

Survey of restored wetland habitat
J. Tucker, A. Redmond, B. Kerans, C. Theiling
The Riverlands Environmental Demonstration Area is a recently restored riverine wetland habitat located near Lock and Dam 26 on the Mississippi River. The extreme flooding in 1993 destroyed most of the introduced prairie plant species, but they were replaced by a wide range of native species and "weeds." Fish community diversity expanded considerably after the flood, but harsh environmental conditions (low oxygen levels) eliminated the least tolerant species over the winter and hot summer months. Amphibians, reptiles, and small mammals transported out of the site by floodwaters had not recovered as of spring 1995. Recolonization of the area is probably impeded by highways and levees that reduce or preclude animal movements.

Invertebrate response to extreme flooding
C. Theiling, J. Tucker, R. Sparks
The 1993 flood provided an opportunity to test the floodpulse concept, which predicts that organisms will take advantage of nutrients released from newly flooded soils. Those nutrients should stimulate a pulse of productivity, starting with microorganisms and proceeding up through food chains. Invertebrate densities were much higher on the rising flood than on the falling flood. While not conclusive, these findings were in accordance with the predictions of the floodpulse concept.

Assessment of habitat enhancement
C. Theiling
A review of habitat rehabilitation and enhancement projects, channel maintenance operations, and water-level manipulations for habitat management on the Upper Mississippi River was prepared for the 2nd International Large Rivers Conference. The review concluded that site-specific projects may not be cost-effective for large-scale habitat rehabilitation. Channel maintenance projects provide some hope for large-scale habitat rehabilitation because of the many channel maintenance structures throughout the river, and also because they are self-maintaining. Using navigation dams to manipulate water levels may be the best option for large-scale habitat rehabilitation on the Upper Mississippi River.

Use of floodplains by fish
R. Maher, F. Cronin, R. Sparks
The protracted flood of 1993 provided an opportunity to examine use of flooded terrestrial habitats by fish on the Lower Illinois River. An unusually large number of fish were produced during the flood. However, the overwinter survival of the 1993 year class may have been low because post-flood sampling did not show a strong 1+ year class for most species. Factors other than spawning success determine year-class strength in Upper Mississippi River fishes. We suspect the lack of deep backwater habitats (overwintering habitat) contributes to periodic poor recruitment of Upper Mississippi River fishes.

New technology for restoration planning
A. Redmond
In cooperation with the National Biological Service (Environmental Management Technical Center) and the U.S. Army Corps of Engineers, an ARC/INFO Geographic Information System model was used to help design the Calhoun Point habitat rehabilitation and enhancement project located at the confluence of the Illinois and Mississippi rivers. The model incorporates land cover, elevation, and water-level data to simulate the effects of various levee alignments. Project planners at the Corps of Engineers used the model to test and evaluate several design options before selecting the final plan, which is to be constructed in 1996.

Illinois chorus frog studies at I-255 site
J. Tucker, D. Philipp
The fossorial Illinois chorus frog (Pseudacris streckeri illinoensis), a threatened taxon in the state, is distributed mainly along the Illinois River and scattered along the Mississippi River floodplain from Madison to Alexander counties. A proposed highway interchange near Poag (Madison County) will affect a site where this frog has been heard calling. Research objectives are to determine the distribution of chorus frogs, the approximate number of breeding individuals, and the suitability of three alternate wetland mitigation sites as potential habitat. A strategy to improve habitat for this frog will also be developed.

Effects of altered hydrology on forests
J. Nelson, Y. Yin (National Biological Service)
Regulation of the Upper Mississippi River for navigation altered historic discharge and river stage relationships. These hydrologic changes probably influenced forest communities on the floodplain. Besides the direct effect of permanent inundation of large areas of floodplain forest, water-table disturbances also impacted these forests. The relationship between floodplain forest and hydrologic changes is being investigated using historical survey data and river gauge readings. This historical information should help explain the modern distribution and composition of floodplain forests.

Post-flood tree mortality at Pool 26
J. Nelson, Y. Yin (National Biological Service)
Extreme flooding during the 1993 growing season caused high tree mortality in Upper Mississippi River floodplain forests. Surveys were conducted to quantify total tree mortality and to determine which species, communities, and forest layers were impacted. Approximately 40% of all trees sampled on the Pool 26 floodplain were killed. Hackberry experienced nearly 100% mortality, while oak-hickory communities showed the highest community- level impact. Understory sapling mortality was 80%. Studies of latent tree mortality and seedling regeneration are scheduled for 1995.

Reconstruction of floodplain forests
J. Nelson, Y. Yin (National Biological Service)
Data collected by Government Land Office surveyors mapping and parceling the Louisiana Purchase lands in the early 1800s provide a valuable resource for modern forest ecologists. These data can be used to reconstruct landscapes and vegetation patterns prior to large-scale disturbance by Euro-American settlers. A pilot study near the confluence of the Illinois and Mississippi rivers illustrated the utility of these methods for floodplain ecologists. The study showed landscape changes through time and illustrated the influence that European settlers had on the floodplain. The success of the pilot study garnered wide support for these methods, which may be expanded to cover the entire Upper Mississippi River floodplain system.

Ecological impacts of water-level regulation
C. Theiling
Pre- and post-regulation river stage fluctuation on the Upper Mississippi River was assessed to determine the impact of navigation dams on river ecology. The analysis revealed that post-regulation river stages were significantly increased by navigation dams. Stage variation was reduced by dam operation and the impacts were differentially distributed along the length of individual navigation pools. Upstream pool reaches exhibit the least impact, while downstream pool reaches exhibit the most impact. In some cases, downstream river stages were inverted (i.e., drawdowns). River modifications were extrapolated to a broad range of abiotic and biotic factors with the most pronounced being backwater sedimentation in dam-created habitats.

Red-eared slider reproductive ecology
J. Tucker
Comparative studies of reproductive effort in four populations of the red-eared slider, Trachemys scripta elegans, have been conducted over two years. Results have a strong bearing on various evolutionary theories previously advanced to explain egg size and number in turtles. Furthermore, the influence of the 1993 flood year is outlined.

River fish communities
R. Sparks, T. Lerczak, D. Blodgett
Yearly examination of fish communities is necessary to monitor trends and to evaluate management practices. Seven species that comprised most of catch, by weight and numbers, throughout the river in 1994 included gizzard shad, common carp, smallmouth buffalo, channel catfish, bluegill, largemouth bass, and freshwater drum. The 1994 results are consistent with data from the past five years that indicate fish communities have improved since the survey began in the 1960s.

Illinois River largemouth bass study
P. Raibley, K. Irons, M. O'Hara, D. Blodgett, R. Sparks
The recovery of bass populations in the Illinois River has stimulated an increasingly important sport fishery. To determine some characteristics of the sport fishery, 4,668 largemouth bass were tagged and released from 1992 to 1994. Of these, at least 1,211 (25.9%) were recaptured by anglers. Anglers harvested (ate) about 40% of the tagged bass they caught. Most bass were caught within five miles of the location where they had been released. Catch and release made it possible for anglers to catch the same fish up to four times. These data will be used to develop recommendations to conserve and enhance this important resource.

Winter habitats of Illinois River bass
P. Raibley, K. Irons, M. O'Hara, D. Blodgett, R. Sparks
Little is known about winter habitat requirements of Illinois River largemouth bass. During 1993-1994, radio transmitters were attached to 26 bass to determine the environmental characteristics of the habitats they used in winter. Radiotagged bass wintered in ditches, marinas, and backwaters off the main channel. They seemed drawn to these areas because they were warmer than the main channel and lacked current. Low river levels in winter created stressful conditions in some of these areas, which resulted in fish kills. Suitable winter habitat may be scarce in the Illinois River, and identifying such habitats will aid in preserving and enhancing river fishes.

Population estimates for Illinois River bass
P. Raibley, K. Irons, M. O'Hara, D. Blodgett, R. Sparks
To provide an estimate of the standing stock of largemouth bass, an Illinois River slough was electrofished four consecutive days. All largemouth bass were immediately marked and released. The study was conducted over a short period to minimize movement into and out of the study area. Estimates indicated about 1,600 bass (41 per acre) were present in the 2.5-mile segment. About 25% of the bass were at least 12 inches long. Estimates of numbers and sizes of fish in an area will assist fisheries managers in developing strategies to conserve and enhance the sport fishery.

Environmental Management Program
R. Sparks, D. Blodgett, C. Theiling
The five states of the Upper Mississippi River (UMR) and the federal government are partners in the Environmental Management Program to monitor, maintain, and restore the natural resources of the UMR and its navigable tributaries, including the Illinois River and a portion of the Kaskaskia. Since 1989, the Survey has operated two of the six field stations that use standardized methods to monitor water quality, fish, vegetation, and macroinvertebrate populations in this river-floodplain ecosystem. The stations continue to assess the long-term effects of the flood of 1993 and the zebra mussel invasion on natural resources of the rivers.

Illinois River zebra mussel populations
R. Sparks, D. Blodgett, S. Whitney
Zebra mussels invaded the Illinois River in 1989 via channels that connect the river to Lake Michigan in the Chicago area. Populations of zebra mussels exploded in 1993, especially on the lower Illinois near Grafton where numbers increased from less than 100 to 61,000 per square meter. During 1994, populations at most sampled sites on the lower river crashed, possibly due to poor environmental conditions (high water temperatures and low dissolved oxygen levels). It is likely that zebra mussel populations will rebuild as larvae continue to drift downstream from upstream populations, and that a boom-bust cycle will occur over the next several years.

Resurvey of mussels in the Illinois River
R. Sparks, D. Blodgett, S. Whitney
In the early 1900s, the Illinois River was the most productive mussel stream in North America. However, overharvesting for the button industry, pollution, and habitat alterations reduced the diversity of mussels from 47 species to 27 by 1966, the date of the last extensive survey. Since then, the pearl button industry collapsed and environmental legislation improved water quality. However, mussels face new threats today (i.e., zebra mussels and harvest for the cultured pearl industry). Native mussel mortality during 1994 was positively correlated with zebra mussel densities in 1993, indicating a latent effect. Differences in mortality rates among native mussel species may be due to behavioral differences.

Transport of zebra mussels by divers
R. Sparks, D. Blodgett, L. Camlin, J. Stoeckel
After introduction, the European zebra mussel spread rapidly through the Great Lakes and into inland waterways. The potential for SCUBA diver transport of zebras was investigated by exposing divers to zebra larvae and adults in the Illinois River. Calculated numbers of larvae collected on diving suits ranged from 0 to 514 per suit, and up to 40% were alive 3.5 hours after the divers surfaced. No adult zebras attached to the divers. The potential for accidental transport by divers can be reduced by rinsing wetsuits and equipment in hot and/or chlorinated water or thorough drying after diving in infested waters.

Evaluation of a mussel sanctuary
R. Sparks, D. Blodgett, S. Whitney
In 1987, the Illinois Department of Conservation established seven mussel sanctuaries on the Mississippi River to protect populations from overharvest and to provide beds that could be studied without the confounding effects of harvest. An evaluation of the Reach 15 sanctuary near Rock Island was initiated in 1994. Species richness, density, size, and age structure of the mussel population in the sanctuary are being compared with other beds in the reach from which shells can be harvested legally. Preliminary results indicated the density of commercial-size shells is lower than expected in the sanctuary, suggesting commercial shells are being taken illegally.

Sediment toxicity in the Mississippi River
R. Sparks, D. Stoeckel, D. Blodgett
Chronic toxicity was detected in Reach 15 of the Mississippi River near Rock Island in 1993, a reach where the Illinois Department of Conservation has established a sanctuary for native mussels. Toxicity appears to be patchy and episodic because it was detected in 1994 in different areas. Test protocols are also being developed for native species that live in the sediments, instead of standard reference species, such as Ceriodaphnia dubia, that do not.

Walleye survival and growth
D. Clapp, D. Wahl
Survival and growth of four size-groups of stocked walleye are being investigated at Ridge Lake. Survival and growth of walleye may be influenced by size at stocking, available forage, potential predators, and competition. In the first three years of the study, the major forage available to newly stocked walleye was young-of-year bluegill. In 1989, however, gizzard shad were accidentally introduced, and they have become equally important prey. By looking at data from before and after the introduction of gizzard shad, researchers can evaluate the impact of the change in forage base on the walleye population, information that will affect decisions on forage manipulation and predators in small impoundments.

Bluegill and crappie for food fish
D. Wahl, C. Kolar
Aquaculture of food fish is a fast-growing industry in the Midwest. Bluegill and crappies are popular food fish with a high market potential; however, much information is needed before these species are commercially viable. The Natural History Survey is collaborating with other research institutions through the North Central Regional Aquaculture Center to develop technologies for successful and efficient culture of these species. The project will identify and refine production technologies, determine optimum stocking densities and rearing temperatures, and develop low-cost, high-performance commercial feeds for these species, their polyploids, and hybrids.

Evaluation of walleye stocking program
D. Clapp, D. Wahl
Little is known about the relative importance of various factors influencing walleye stocking success. Two basic strategies have been developed: to stock large numbers of relatively inexpensive fry in the hopes that they will survive and contribute to the fishery, or secondly, to stock smaller numbers of more expensive intermediate to advanced fingerlings, assuming that larger fish will lead to strong year classes. Both strategies have had variable success and the reasons are not known. The current study is investigating the influence of various biotic and abiotic factors on walleye stocking success.

Evaluation of esocid stocking strategies
D. Wojcieszak, D. Clapp, D. Wahl
The stocking program for muskellunge and tiger muskellunge is being evaluated to determine optimal stocking strategies for these fish in Illinois. Mechanisms of survival and growth of various sizes of esocids after impoundment stockings are being compared and used to develop a bioeconomic model. Second, the effect of rearing method in determining susceptibility to largemouth bass predation is being evaluated in impoundment stockings, as well as pond and laboratory experiments. Finally, an assessment of different genetic stocks of muskellunge throughout North America and their performance characteristics are being evaluated in physiological experiments.

Exotic zooplankton in Illinois
C. Kolar, J. Boase, D. Wahl
Exotic species lack natural predators and other population control mechanisms found in their native ranges. For these reasons, exotic species can have profound effects on native populations. Recently, Survey researchers discovered Daphnia lumholtzi, a species of zooplankton found in Australia, Asia, and Africa, to be the dominant daphnid in Lake Springfield by late summer. Experiments are being conducted to examine the thermal tolerances, competitive ability, and vulnerability of D. lumholtzi to fish predation. Results of these experiments will aid in predicting the potential ecological impact of this exotic daphnid on aquatic communities.

Juvenile walleye growth and survival
C. Kolar, D. Wahl
Although juvenile walleye are stocked extensively throughout most of the United States, not much is known about the mechanisms controlling their growth and survival. As a result, the success of walleye stockings has varied considerably. Survey scientists are evaluating the importance of prey base to juvenile walleye growth and survival in laboratory and pond experiments. Differences in prey morphology and behavior will likely impact juvenile walleye success. Fisheries managers stocking juvenile walleye will be able to use this information to select, based on the prey base, which reservoirs will enhance the success of the stocked walleye.

Lake chubsuckers as forage in small ponds
R. Eberts, V. Santucci, Jr., D. Wahl
Young bluegills are the principal forage fish in most small impoundments. However, in this area and other northern waters, piscivorous (fish-eating) game species, such as largemouth bass, walleyes, northern pike, and muskellunge, grow slowly when bluegills are the only fish species available as prey. Also, bluegills often overpopulate and become stunted, which usually leads to an eventual decline in the reproductive success of piscivorous species. The purpose of this project is to evaluate lake chubsuckers as an alternate or supplemental forage fish for small impoundments.

Effects of starvation in young walleye
J. Jonas, D. Wahl
The direct and indirect effects of starvation in young walleye are being investigated in both behavioral and laboratory investigations. Walleye are being studied after varying periods of starvation at four critical periods in the first year of life. Direct effects of starvation are being observed as changes in total body energy, condition, and mortality rates of fish. The indirect effects of starvation may be seen as a decrease in foraging efficiency or an increase in a fish's vulnerability to predation. From this research we will create predictive models for determining the relative health of young walleye.

Aquaculture of walleye
T.Galarowicz, D. Wahl
Walleye are popular as food and sport fish throughout the country, but commercial harvesting is not allowed in the United States. As a result, there is an increased interest in culturing walleye to market size to meet this demand. In response, the North Central Regional Aquaculture Center, a multi-research institute organization that includes the Natural History Survey, has focused on developing techniques for commercial culture of walleye while evaluating growth, feed efficiency, and stress response under various culture conditions. Survey researchers will use a bioenergetics model to study these different components affecting culture success.

Creel surveys on Illinois impoundments
S. Sobaski, P. Perea, B. Carroll,
R. Mahnesmith, P. Bayley, D. Philipp
Since 1987, Survey scientists have conducted angler surveys on a total of 68 state-managed lakes to estimate the total fishing effort; species, numbers, and weight of fish harvested and released; and the species targeted by anglers at these lakes annually. The lakes chosen for roving and access point surveys are representative of the majority of lake types occurring throughout the state. The data collected are useful to the fisheries management of these lakes, especially in evaluating the effects of short-term management changes and supplemental stocking on yield and catch per angling effort and the impact of sport fishing intensity on the resource.

Improving lake resource management
P. Bayley (Oregon State University), S. Sobaski, R. Riedel, D. Philipp
The Fisheries Analysis System is an integrated approach to management and research on Illinois lakes. Initiated in 1984, it incorporates a wide range of information on state-managed lakes, including data from fish population and creel surveys, lake physic-chemical properties, and environmental and management histories. Data from more than 300 lakes have been accumulated to date. This information is used directly by Department of Natural Resources managers at district and statewide levels in their management planning. Research is under way using this system to predict fish population trends based on past environmental and management histories so that future fisheries management will be more scientifically based.

Illinois Streams Information System
D. Schneider, D. Szafoni
At present, the Illinois Streams Information System (ISIS), developed by the Department of Conservation, is a relational database organized by river and river mile. The narrative text within ISIS represents a valuable compilation of information for managing surface waters, but the text format is not presently compatible with many other state databases housed within a Geographic Information System (GIS) framework. Work has been completed to allow the information in ISIS to be accessed and referenced by other state databases within a GIS framework. During the conversion, Survey staff managed the ISIS database and responded to requests for information.

Ecology of Hine's emerald dragonfly
D. Soluk, B. Swisher
Hine's emerald dragonfly is a federally-listed endangered species whose only known populations occur in a short stretch of the Des Plaines River valley and in Door County, Wisconsin. The range of this species is extremely restricted probably because of the specific habitat requirements of the larvae. Given this, it is important that any development or modification of the small area occupied by the Des Plaines River valley population of Hine's emerald dragonfly be scrutinized for possible effects on this species. Researchers are conducting comprehensive studies of the ecology and behavior of both adult and larval Hine's emerald dragonflies to determine their specific habitat requirements and to understand what measures must be taken to assure the long-term survival of this species.