Surveys and investigations for sportfish management in lakes and rivers in Illinois Annual Report July 1, 2016 through June 30, 2017

J. J. Parkos III, T. Detmer, A. P. Porreca, E. Effert-Fanta, M. J. Diana, D. H. Wahl

Research output: Book/Report/Conference proceedingTechnical report


Although stocking crappie (Pomoxis species) has been increasingly applied to populations with poor recruitment and high angling pressure, the highly variable success rate of these stockings may reduce the utility of this management approach. The success of crappie stocking may depend in part on which type is stocked as White and Black Crappie growth and survival often differ in lakes and ponds where they co-occur. Blacknose Crappie is a strain of Black Crappie stocked in Illinois from a hatchery population raised by the Tennessee Wildlife Resource Agency and there are no published studies comparing their growth rates and survival with other crappie types. To assess the relative growth and survival of stocked Black, White, and Blacknose Crappie at a whole-lake scale, juvenile fish from Sam Parr Biological Station rearing ponds were stocked into Ridge Lake in the fall of 2013. Following stocking, relative catch of White, Black, and Blacknose Crappie and their mean size was determined from fishery and fishery-independent sampling. In this segment of Job 101.3, we report electrofishing catch per unit effort (CPUE) from spring 2014 through spring 2017 and angler catch-rates from 2014-2016 summer creels. The two strains of Black Crappie were detected in the creel and electrofishing samples approximately one year following introduction to Ridge Lake, while White Crappie were first collected by creel and electrofishing surveys two years after stocking. Number of crappie captured per seasonal fishing effort in Ridge Lake has increased 51 times since 2014 and 5 times since 2015, with Black and Blacknose Crappie constituting the majority of the catch. There is currently no evidence of crappie reproduction in Ridge Lake. Initial abundance has affected time to first detection and contribution to the creel as White Crappie, the crappie type stocked at the lowest density, was first detected in Ridge Lake a full year after the two Black Crappie strains. We will continue to monitor the fate of crappie stocked into Ridge Lake and refine our assessment of how growth conditions and stocking densities influence contribution to the fishery and detections with fishery-independent sampling. Largemouth Bass Micropterus salmoides are commonly stocked throughout their native range, but survival of stocked fish is variable and often low. Hatchery fish may have difficulty switching to natural forage and providing feeding experience with natural prey in the rearing environment could result in improved growth and survival of Largemouth Bass after stocking. In previous segments, we conducted pond experiments to evaluate differences in growth and survival of Largemouth Bass reared on pellets, Bluegill, or Fathead Minnow. Largemouth Bass reared on one of these three diets were stocked into ponds containing Bluegill prey. After two months, pellet-reared Largemouth Bass were significantly smaller than either Fathead Minnow or Bluegill-reared fish, while Fathead Minnow and Bluegill-reared fish were similar. Fathead Minnow-reared Largemouth Bass had lower survival than Bluegill-reared fish, but no other survival differences were observed. To determine possible mechanisms influencing differential growth and survival of juvenile Largemouth Bass, we also conducted laboratory experiments examining the influence of prior feeding experience (pellets, Bluegill, or Red Shiner Cyprinella lutrensis) on foraging behavior and prey capture success in tanks. Largemouth Bass reared on live forage captured prey faster, ingested more prey, and had higher capture efficiencies compared to fish reared on pellets. In this segment, we concluded Job 101.4 by completing analysis and preparing a paper for peer reviewed publication. Combined, pond and laboratory experiments show prior acclimation to live prey may ultimately be beneficial to increasing recruitment of stocked hatchery Largemouth Bass. We recommend hatchery managers consider 6 alternative rearing techniques to acclimate Largemouth Bass fingerlings to natural prey prior to stocking. Harvest regulations are commonly employed by fisheries managers to protect overharvest of fish populations or manage size structure. There are a large variety of regulations used in Illinois with varying management goals. In Job 102.1, we continued to assess largemouth bass populations in lakes with varying harvest regulations. In this segment, we used three approaches to examine how regulations might be affecting largemouth bass populations in Illinois lakes, each analysis increasing in control of variables and thus a more restricted number of lakes. We used the data that was available in the IDNR database from 1998 through 2016. The default largemouth bass regulation in Illinois is no length limit with a 6 fish bag. This was by far the most common regulation, followed by a standard 14 inch 6 fish bag. Slot limit lakes continued to have the highest abundance of adult largemouth bass of 14-inches and greater, preferred, and memorable sizes, but there is also large variation in catch rates in these lakes. Slot limit and Lowered Bag limit lakes have the highest abundances of total largemouth bass, but these effects are largely driven by high catch of young-of-year size classes. At larger size classes, Raised Raised Length and Raised Length/Lowered Bag limits had the greatest catch rates of largemouth bass. These two regulation types both have a more restricted harvest especially at larger sizes and may be resulting in greater abundance of larger fish. However, when more restrictive analyses were performed in which we examined the same lakes before and after regulation changes, there was little evidence that regulations, which included lakes that changed from Bag limits to Raised Length/Lowered Bag limits, had any effect on largemouth bass catch rates. The evidence for effects of regulations on largemouth bass remains mixed. Some very basic analyses show some indications for effects of highly restrictive regulations, however when some of the sources of variation are controlled for, those effects are not observed. There are a large number of potential factors that can affect the ability to detect effects of regulations in Illinois lakes and in order to get a more definitive answer, a more controlled experimental procedure should be implemented to specifically examine this question in the future. We also continued to examine regulations in Illinois lakes and how they relate to crappie populations. In Job 102.2, we identified lakes with listed regulations as well as electrofishing data available in the IDNR database from 1998 – 2016. We summarized catch rates of crappie in different size classes and compared them across regulation types. A large majority of lakes in Illinois had unregulated crappie populations. The most common regulation types were bag limits and length/bag limits. Bag limits ranged from 5-30 fish per day and length limits were either 9 or 10 inches. In an analysis of different regulation types for which there was sufficient data, we did find some evidence for regulations having an effect on crappie populations. Lakes with Length and Bag limits had a higher overall catch of both total crappie and fish over 10 inches. However, our more restricted analysis that examined specifically lakes that had data before and after a change in regulations, there were no differences in catch rates of crappie at any of the size classes that we examined. We will continue to expand the time series in future segments to increase the number of years and sample size of lakes where we can evaluate changing regulations. However, the mixed results and a lack of control of factors that could affect the ability to detect the effects of regulations again suggest that a more controlled experimental approach to examining regulation effects on crappie populations in Illinois Lakes is 7 needed. We plan on addressing some of these issues by conducting controlled studies of fishing regulations in Angling tournaments are increasing in popularity. Although most tournaments practice live release, there are many sub-lethal impacts resulting in reduced fitness or delayed mortality, which has been shown to be high under certain conditions. Most of the focus in the literature has been on measuring and reducing the stress of individual fish caught and transported in tournaments. Little work exists, however, on population level dynamics. Specifically, do tournaments influence fish at the population level? In Job 102.3, we attempt to address this question by characterizing fish populations in reservoirs with varying levels of tournament activity as well as through a long term whole lake tournament experiment. In the first portion of the tournament study we worked with lake managers and tournament directors to obtain competitive bass fishing tournament results to quantify tournaments conducted from 2002 to the present. We observed great increases in tournament frequency in the past two years, in particular with the higher frequency of smaller tournaments. We did not detect any changes in abundance or size structure of largemouth bass vulnerable to tournament angling or any changes in production of young-of-year fish related to tournament pressure. Thus far, there is no evidence that tournaments negatively affect largemouth bass populations. We will continue to collect tournament and largemouth bass population data on these lakes and add additional lakes to this analysis as part of future segments to more precisely understand the influence of tournaments on largemouth bass populations. Although no effect was detected at current levels of tournament pressure, of particular importance with the further expanding of this sport is an evaluation of whether there is a threshold where by tournament pressure has a negative effect, and further still if there are reservoir characteristics that result in changes in that threshold leading to greater or lesser susceptibility of largemouth bass populations. In the second portion of the tournament study, we continued to evaluate tournament style angling on Ridge Lake during the largemouth bass spawning season to determine how tournaments influence reproduction, abundance, and growth of largemouth bass. In this segment we conducted a tournament free year on Ridge Lake for an additional control year and compared recruitment of largemouth bass collected in tournament years to control years with no tournaments. Experimental angling tournaments were conducted on Ridge Lake in 2007, 2010, 2013, and 2015, providing assessment of 4 years of largemouth bass recruitment in years with tournament angling to compare to 7 years of non-tournament angling. Preliminary results from the experiment at Ridge Lake have not yet shown clear evidence of reduction in recruitment of young-of-year largemouth bass due to springtime tournaments or changes in adult populations. We will continue to analyze results from this experiment and determine if additional years of tournaments are needed to make final recommendations. In Job 103.1, we continued to evaluate strategies for vegetation sampling and management in Illinois reservoirs. We also used an experiment to assess the importance of coarse woody habitat (CWH) to sportfishes. We conducted field sampling of vegetation and largemouth bass recruitment metrics on 15 lakes, including 6 for control conditions, three for rehabilitation conditions and two for vegetation removal. Largemouth bass populations, vegetation, prey resources, and fish communities were monitored. In this segment, we continued to utilize side scan sonar mapping techniques to quantify vegetation and woody habitat in lakes. We conducted shoreline transects on all lakes and imported images into ArcGIS. Through this job, we have developed quantification techniques and will report findings in future segments. In 8 addition, we have developed a standard protocol for vegetation sampling that can be used by other biologists in Illinois. This protocol will be distributed to the IDNR within future segments. We will also continue to evaluate trends in fish populations related to vegetation density in future segments. We tested three hypothesized mechanisms linking coarse woody habitat and fish populations by monitoring fish growth, survival, and reproduction across a gradient of coarse woody habitat addition in ten experimental ponds. Coarse woody habitat is a common littoral habitat feature in freshwater lakes and reservoirs, however, the abundance of this habitat in many lentic systems is threatened by urban shoreline development as well as reservoir ageing. Several ecological functions linking coarse woody habitat and fish populations in lentic ecosystems have been proposed but have not been simultaneously evaluated in replicated experimental conditions. Our results indicated a positive linear relationship between coarse woody habitat density and adult largemouth bass growth rates. The increase in adult largemouth bass growth rates coincided with reduced survival of fish groups vulnerable to largemouth bass predation (juvenile and young of year fish) but no relationship with adult bluegills that were too large to be consumed by largemouth bass. We also found no relationship between CWH density and growth of invertivorous fish or initial abundance of young-of-year largemouth bass or bluegills. Thus, addition of CWH in lakes where this habitat has been removed may be an effective tool for fisheries managers to improve growth and condition of adult largemouth bass, but offer little to improve sunfish populations. Because of the apparent benefits of CWH additions to largemouth bass, artificial habitat that mimics CWH will be evaluated in future segments. The role of habitat in structuring sportfish populations in mid-sized rivers is not well known compared to larger rivers and small streams. In mid-sized river, there is no standardized method for evaluating fish-habitat associations in Illinois. To guide management strategies and habitat restoration efforts, research is needed to develop fish and habitat sampling procedures that allow assessments of habitat value for sportfish in mid-sized rivers. In Job 103.2, we continued our analyses of habitat in the Kaskaskia and Embarras Rivers at multiple spatial scales using side scan sonar mapping, habitat transects, and microhabitat targeted sampling. Three segments (upper, middle, lower) were sampled in both rivers in Spring and Summer 2016 to incorporate longitudinal and seasonal variation in fish assemblage and habitat conditions. Electrofishing was conducted in each segment at the reach scale with 15 minute transects and at the micro scale in sites with homogeneous habitat. Analyses of side scan imagery revealed higher biomass and densities of large woody debris in the Kaskaskia River compared to the upper and lower reaches of the Embarras River. We found higher total catch rates in the Kaskaskia River, but fish species richness was similar in the two rivers. Fish assemblages did vary among rivers due to higher abundances of gizzard shad, yellow bass, and smallmouth buffalo in the Kaskaskia and higher abundances of river carpsucker, shortnose gar, and Moxostoma species in the Embarras. Microhabitat sampling results indicated habitat associations with fish abundance for the presence of woody habitat, channel position, and dominate substrate. In the Kaskaskia River, yellow bass, black crappie, and largemouth bass had significantly higher catch rates in microhabitat sites with large woody debris. Similar trends were observed for sportfish in the Embarras River. We also observed higher total catch rates on gravel and cobble substrates as well as in inside bends and shoreline runs. Future analyses will be used to refine our sampling methods and determine the size of habitat unit and number of sampling sites required 9 to associate sportfish to habitat type in mid-sized rivers. In the next segment, we will continue to work closely with IDNR fisheries biologists to determine which rivers may be targeted for restoration and conduct our fish-habitat assessment at those locations to establish important pre-restoration data before habitat improvements are made. As crappie are among the most targeted sportfish in US reservoirs and recruitment variability greatly complicates effective management of these fisheries, further effort is required to disentangle the processes responsible for variable year-class strength. In Job 104.3, we developed a stock-recruitment model from data collected on the 2016 year-class in eleven lakes and tested offshore zooplankton, crappie reproduction, and densities of larval Dorosoma and Lepomis as potential sources of variation in recruits produced per adult. Larval Dorosoma and Lepomis were considered to be either competitors with crappie for zooplankton or a source of food for piscivorous crappie juveniles. The crappie stock-recruitment relationship was dome-shaped, providing evidence for density dependent effects operating during crappie early life stages. A positive relationship with offshore zooplankton and density dependence during the larval life stage supported crappie recruitment being limited by competition for zooplankton during early life stages with reduced recruitment at high stock abundances potentially resulting from predation by adult fish on prerecruits. The influence of zooplankton biomass in offshore habitats underscored the importance of limnetic conditions for crappie recruitment and the challenge of measuring first-year growth and survival of a species whose juvenile life stages are lived off shore. We will need to integrate data from other year classes to verify the magnitude and consistency of these relationships. In Job 104.3, we also assessed among-lake variation in turbidity and prey resources their effect on the dominance of one crappie type versus the other. Black Crappie and White Crappie are sympatric throughout most of the United States, but lakes are normally dominated by a single species. Across a wide range of White Crappie abundance, Black Crappie CPUE was low across all of the study lakes. Only White Crappie increased in abundance with shad larvae, perhaps because of the greater importance of fish prey to White Crappie diets than Black Crappie. Black Crappie may be limited in number because of the low levels of aquatic vegetation and water clarity typically found in many Illinois reservoirs. Sportfish populations can vary drastically over the lifetime of a reservoir. Large reservoir fisheries, such as those in Lake Shelbyville, have high value in Illinois and provide important fisheries that are heavily utilized by anglers. In Job 104.4, we analyzed long term data on sportfish populations in Lake Shelbyville to characterize how the fishery in the lake has changed over time. We conducted spring and fall electrofishing in Lake Shelbyville and combined it with historic data for a timeline of 1998-2017. Although there was variation in catch rates for most sportfish in Lake Shelbyville, no consistent reduction or enhancement of these fisheries existed. Muskellunge and the largest size category of largemouth bass declined while both crappie species, bluegill, and yellow bass increased in abundance. In addition, there were enhancements in maximum size of white bass, white crappie, and yellow bass. This study is now concluded, but if continued would benefit from an enhancement in scope to more closely examine what abiotic 10 and biotic factors drive variation and if management strategies can be implemented to counter negative patterns and maintain greater consistency in popular fisheries. In job 104.5 we initiated assessment of channel and flathead catfish catches in all lakes sampled as part of this study. We collected low numbers of flathead catfish in electrofishing and fyke net surveys. Channel catfish catch rates were not related to stocking density. Further, channel catfish catch rates were not higher in lakes that were stocked when compared to those that were not stocked. Due to low catch rates, we were unable to assess recruitment. Future research will depend upon interest to continue this study by the IDNR. In job 105.1 we evaluated differences in catch rates and efficiency for sportfish sampling with AC and DC electrofishing gears. Despite the prevalence of electrofishing as a sampling technique and its effects on fish being well-studied, there is little research directly comparing efficiency of different electrofishing gears in sampling the same fish assemblages. The IDNR has historically used boat AC electrofishing for standardized sampling of fish populations in lakes throughout the state. However a shift to pulsed DC electrofishing is underway. Given that the majority of fisheries data in Illinois to this point has been collected via AC electrofishing, further research is needed to determine if comparisons can be made between AC and DC electrofishing sampling efficiency and to develop standardized sampling methods. We conducted AC and DC boat electrofishing on 12 lakes distributed throughout Illinois during the spring and fall of 2012–2017. Lake Charleston, Clinton Lake, Dolan Lake, Forbes Lake, Homer Lake, Lincoln Trail, Lake Mattoon, Lake Mingo, Lake Paradise, Lake Shelbyville, Stillwater Lake, and Walnut Point Lake were used for analysis. Lakes were AC or DC electrofished on one date during the fall and spring of each year. We calculated CPUE for all sunfishes, bluegill, black and white crappie, gizzard shad, all catfishes (including bullhead species), channel catfish, common carp, and 3 size classes of largemouth bass (under 200 mm, adult over 200 mm, and fish over 356 mm) and compared catch rates of AC to DC gear. We found most relationships between AC and DC electrofishing to be positive, but often inconsistent, among species and between seasons. We found DC electrofishing to consistently sample a greater number of fish h-1 than AC electrofishing. Sampling with DC gear yielded higher catch rates for all species except gizzard shad and catfishes. However, neither of these species had significantly different catch rates between gears. A significant difference in CPUE between electrofishing gears was only observed for largemouth bass and common carp. A lack of statistical difference between gears for most species suggests that although catch rates between gears may be variable, mean CPUE between AC and DC electrofishing is similar. Size structure of fish sampled with AC and DC electrofishing was variable within season. Channel catfish was the only species in which a similar length distribution was collected within both spring and fall sampling seasons. We advise extreme caution when making inferences across time with changing gear types. We have demonstrated that largemouth bass in particular are not recruited equally to the two gear types. Differences between gears were likely influenced by environmental conditions, density of fish at a given site, catchability during different seasons, reservoir size, and netter efficiency. High variation within long-term electrofishing data on multiple lakes over several years may be unavoidable due to changes in species assemblages and 11 environmental conditions. Further research in which all variables aside from electrofishing gear are kept constant may be needed to establish a consistent relationship between AC and DC electrofishing. There are also differences among several manufacturers’ DC electrofishers which may influence efficiency and catch rates. Currently, a variety of DC electrofishing equipment is used throughout the state. Thus, in order for standardized sampling to be utilized through time, differences among DC gear types will be examined in future segments.
Original languageEnglish (US)
PublisherIllinois Natural History Survey
StatePublished - Aug 2017

Publication series

NameINHS Technical Report 2017 (27)


  • INHS


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