Surveys and investigations for sportfish management in lakes and rivers in Illinois ANNUAL REPORT July 1, 2017 through June 30, 2018

Joseph J. Parkos III, Anthony P. Porreca, Thomas M. Detmer, Michael A. Nannini, Eden L. Effert-Fanta, David H. Wahl

Research output: Book/Report/Conference proceedingTechnical report


Supplemental stocking of crappie is becoming an increasingly common practice for enhancing poorly performing crappie fisheries. In Job 101.1, we assessed the relative stocking performance of Black Crappie, White Crappie, and the Blacknose variant of Black Crappie at a whole-lake scale by experimentally simulating a stocking event. Pond-reared Black (N=1,000), White (N=300), and Blacknose (N=1,000) Crappie 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 annual creel surveys, beach seines, and electrofishing. After an initial lag post-stocking, all three types of crappie recruited to both the creel and the electrofishing gear. None of the crappie varieties were ever captured during beach-seine sampling. Initial stocking density affected time to first detection as White Crappie, the crappie variety stocked at the lowest density, was first detected in Ridge Lake a full year after the two Black Crappie strains. The two crappie types stocked at the highest densities were not detected by electrofishing surveys until they had reached 142-154 mm total length (TL), whereas White Crappie were not captured by electrofishing until they were 227 mm TL. As they have grown in size, angler catch rates for the three crappie types have also increased. Similar to electrofishing CPUE, the first captures in the fishery and highest contribution to angler catch have come from the crappie types stocked at the highest densities. After four years, the three crappie varieties have attained similar average sizes in Ridge Lake. All three crappie introductions into Ridge Lake have been successful, as all three have been present in the lake four years after stocking with no further introductions and continue to contribute to the fishery. 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 initiated preliminary data collection on lakes chosen to be part of an experimental assessment of crappie and bluegill regulations. In consultation with Illinois Department of Natural Resources fisheries biologists, we identified twelve lakes to include in an experimental assessment of crappie and Bluegill regulations. A sampling regime for water quality, prey resources, and fish assemblages was implemented in May 2018 for the 12 study lakes, with creel surveys conducted at six of the lakes (Evergreen Lake, Forbes Lake, Homer Lake, Lake Mattoon, Lincoln Trail Lake, and Sam Parr Lake). We chose to focus creel surveys on a subsample of lakes in the first year so as to collect a sufficient number of survey-days per lake to be able to properly characterize fishing pressure on these systems. Survey effort for each lake is being divided among morning/early afternoon (0730 -13:30) and afternoon/early evening hours (13:30 – 19:30), as well as weekday and weekend dates. Creel survey questionnaires are designed to assess fishing effort, harvest, factors influencing choice of lake, perceptions of bluegill and crappie quality, and level of angler experience (Appendix 102.1.1). Preliminary data from June interviews show that anglers perceive room for improvement in the quality of both fisheries, with average rankings of fishing quality centered around “medium” scores. The population of anglers fishing each lake varied considerably in their level of experience fishing these locations, and so far, few anglers were found to be highly specialized Bluegill or crappie anglers. In June, crappie species were the most commonly harvested taxa. Creel surveys, environmental measurements, and population assessments will continue for three years prior to the implementation of experimental regulations. These data will be used to characterize the environmental conditions and angler behaviors that may influence the efficacy of harvest regulations. During this period of pre-data collection, we will discuss options for experimental regulations and use the data to guide assignment of lakes to treatments and controls. 6 In Job 102.1, we also examined regulations in Illinois lakes and how they relate to crappie populations We identified lakes that had both listed regulations as well as electrofishing data available in the IDNR FAS database from 1998 – 2017. To determine if regulations put in place on Illinois lakes potentially affect crappie populations in the state, we used three approaches that increased in design rigor, but also restricted the number of lakes that could be included. In the simplest analysis, we found some evidence for regulations having an effect on crappie populations. Lakes with Length and Bag limits had a higher overall abundance of both total crappie and fish over 10 inches. However, our more restricted analysis that looked specifically at lakes that had data before and after a change in regulations found no differences in catch rates of crappie at any of the size classes examined. Thus, the evidence for effects of regulations on crappie populations in Illinois lakes remains mixed. However, the current analysis lacked firm controls on potential confounding factors that could impact our ability to detect any effects of regulations. These results support the importance of using a more controlled, experimental approach for examining regulation effects on crappie populations in Illinois Lakes. In Job 102.2, we continued to assess largemouth bass populations in lakes with varying harvest regulations. 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 FAS database from 1998 through 2017. Across all sizes, Slot limit and Lowered Bag limit lakes have the highest abundances of largemouth bass, but these effects are largely driven by high abundance of young-of-year size classes. At larger size classes, Raised Length and Raised Length/Lowered Bag limits had the greatest abundance 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 by comparing the same lakes before and after regulation changes, there was little evidence that regulations, including lakes that changed from Bag limits to Raised Length/Lowered Bag limits, had any effect on largemouth bass catch rates. The evidence for regulation effects on largemouth bass remains mixed. The least restrictive analyses provided some indications for effects of highly restrictive regulations, however when other sources of variation are controlled for, those effects are not observed. There are many potential factors that can influence 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. Several studies between the 1980s and early 2000s showed an impressive rise in frequency of angling tournaments. Bass tournaments in particular have shown some of the most dramatic increases. Although most tournaments practice live release, some studies have indicated that sub-lethal impacts can result in reduced fitness or delayed mortality. Under some conditions, these sub-lethal effects have been shown to be high (> 50%). Currently, most of the literature has focused on measuring and reducing stress of individual fish caught and transported in tournaments. Few studies, however, have focused on understanding the effects of tournaments on population responses, with empirical studies being particularly uncommon. In Job 102.3, we characterize tournament pressure, evaluate the relationship between tournament pressure and largemouth bass populations, and experimentally investigate whether tournaments held when fish are more vulnerable during spawning disproportionately influence largemouth bass recruitment. This was accomplished by characterizing fish populations in reservoirs with 7 different levels of tournament activity and through a whole-reservoir experiment of tournament manipulation. Currently, these projects are both being organized into manuscripts. In the first portion of the study of tournaments, bass tournament data were obtained from reservoir managers and tournament directors to quantify and characterize tournaments conducted over the 15-year period from 2002 to 2015. In this portion of the study it was shown that tournament characteristics are influenced strongly by reservoir size and abundance of catchable largemouth bass. It was also shown that within-year patterns in tournament pressure differed between power plant and non-power plant lakes, in that there was more even seasonal distribution of tournament pressure in power plant lakes than in non-power plant lakes, where pressure was greatest from April through August. Also of note, there were indications that tournament-angler efficiency at capturing fish has increased, based on higher numbers of bass caught per angler per effort relative to bass population size as measured by IDNR electrofishing. In the second portion of the tournament study, we analyzed data on the effects of tournament style angling during the largemouth bass spawn on the largemouth bass reproduction and abundance in Ridge Lake. In this segment we analyzed data and began organizing a manuscript to evaluate tournament and tournament free years. Experimental angling tournaments during the spring spawn were conducted on Ridge Lake in four years (2007, 2010, 2013, and 2015) and were compared to 7 control years (2008, 2009, 2011, 2012, 2014, 2016, and 2017). Despite numerous studies indicating that fishing has a negative effect on the reproductive output of individual fish and therefore could negatively influence populations, analyses from the present study suggest that there is no evidence of a strong negative effect of spring tournaments on spring recruitment of largemouth bass in Ridge Lake. In Job 103.1 we continued to evaluate artificial and natural habitat structure additions for improving sportfish populations. A pond experiment was conducted during fall 2017 at the Sam Parr Biological Station to evaluate the relative responses of fish and macroinvertebrates to natural wood versus artificial structures. Each pond was assigned a single habitat type (n = 5 ponds/treatment), was colonized naturally by macroinvertebrates, and then stocked with juvenile largemouth bass. The experiment was run for three months, after which time each pond was drained and surviving largemouth bass were collected to estimate fish growth and production. Abundance, biomass, species richness, and Shannon Diversity of benthic macroinvertebrate taxa were assessed after each month and upon completion of the experiment. Mean largemouth bass growth within ponds with artificial habitat was not influenced by habitat type. Macroinvertebrate assemblages contained more taxa on artificial structures, but diversity biomass were not different between structure types Abundance of macroinvertebrates was higher on natural wood structure compared to artificial structure upon completion of the study. Results of this experiment suggest that both natural and artificial structure types may be sufficient for habitat enhancement as they both concentrate prey resources that provide forage for predatory fishes such as largemouth bass. We will evaluate the influence of habitat complexity and habitat arrangement on predator-prey interactions in a second pond experiment conducted August-October 2018. As part of a collaborative effort with the Illinois Department of Natural Resources and Army Corps of Engineers, the Kaskaskia Biological Station is evaluating the efficacy of artificial habitat structures in Lake Shelbyville. A field experiment was initiated during fall 2017 in which six reservoir coves of similar size, depth, shoreline morphometry, and existing submerged habitat were identified as candidate areas for habitat manipulation. Pre-habitat conditions within all coves were sampled for fish, benthic macroinvertebrates, and zooplankton during August 2017. During October 2017, three coves received PVC fish attractors, while three coves remained un- 8 manipulated to serve as control coves. All coves were sampled for fish, benthic macroinvertebrates, and zooplankton post habitat addition during fall 2017 and spring 2018. More fish were collected in treatment coves than control coves with deep water AC electrofishing during the two sampling periods post habitat enhancement. Preliminary data from electrofishing structures at depth indicate that fish community composition within treatment coves has already shifted to structure-oriented sport fishes (e.g., bluegill and crappie species). Data processing of zooplankton and macroinvertebrates is underway and will be reported in future segments. We have initiated sampling as part of a whole-reservoir habitat manipulation that was conducted on Walnut Point Lake during January 2018. Sampling of Walnut Point started in April 2018 and the reservoir has subsequently been sampled at one-month intervals, for a total of four sampling events. Each monthly sampling event consisted of collection of water for nutrients and other water quality parameters, zooplankton, and larval fish. Sportfish will be sampled by DC electrofishing and fyke netting during fall 2018. Lincoln Trail Lake, which is under an identical sampling regime, has been selected as a reference site for the habitat enhancement on Walnut Point Lake. Recommendations on the efficacy of whole-lake habitat enhancements will be made in future segments. The role of habitat in structuring sportfish populations in mid-sized rivers is not well understood compared to larger rivers and small streams. In mid-sized rivers, which are generally defined as 5th to 7th order streams, there currently 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. We conducted habitat and fish sampling of the Embarras and Kaskaskia Rivers from 2016 to 2018. Three reaches in both rivers were selected and sampled over a three-year time period to incorporate longitudinal and annual variation in fish assemblage and habitat conditions. Landscape level habitat conditions were assessed across each reach using the transect method and side scan sonar mapping. 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 similar biomass and densities of large woody debris among reaches of the Kaskaskia river, but temporal variation in densities may be due to flashy hydrological dynamics. The Embarras River has variable densities of large woody debris among reaches but remained constant across years. From the 15-minute electrofishing transects, we collected a total of 1,207 fish representing 45 species in the Kaskaskia River and a total of 928 fish representing 48 species in the Embarras River from 2016 – 2018. Significant differences were found in catch rates and fish assemblages within reaches of the Kaskaskia River but not the Embarras River and temporal variation was not detected for either system. Species richness remained similar across reaches with pooled data across years and rivers. Total CPUE and CPUE of sportfish species did not differ in microhabitat sites with or without CWD in the Embarras and Kaskaskia rivers. Similarly, total CPUE did not differ in microhabitat sites differing in channel position for the Embarras and Kaskaskia rivers. Preliminary microhabitat results suggest that large woody debris and inside bends are important sportfish habitats in Midwestern, warm-water, mid-sized rivers. In the next segment, we will have completed all 2018 field collections and begin analyses incorporating all data. 9 The development of an effective management plan for a species of fish in a given lake is often predicated on a good understanding of that species’ demographics. Preliminary analyses indicate that models of age using eye diameter or total length are mixed, with some species from some lakes indicating that age is most accurately determined by eye diameter, others total length, and others still by a combination of the two. Preliminary multivariate analyses indicated separation for ages for both bluegill and crappie from Ridge Lake. Separation of bluegill was good for two- and three-year old fish, but not for four, five, and six-year old fish. This pattern is similar to what is observed in univariate analyses with total length. Crappie showed better distinction, but there were only three age classes evaluated (1, 2, and 4) and no comparison was therefore possible among older groups that are typically more difficult to compare. All preliminary results suggest that more data are necessary for evaluating the efficacy of these novel approaches. Job 104.2 was a study of factors driving variation among lakes in crappie recruitment. We used eleven populations and four year-classes of Black and White Crappie to quantify stock-recruitment relationships for these two Pomoxis species and the influence of reproductive productivity and prey resources on these relationships. Based on previous documentation of a dome-shaped stock-recruitment relationship for crappie species (Allen and Miranda 2001), we fit the data to a Ricker stock-recruitment function (Ricker 1975): R = S · e (a – bS), where R is relative abundance of recruits and S is adult stock size. Offshore zooplankton biomass, crappie reproductive productivity, and densities of larval Lepomis and Dorosoma were examined as potential sources of variation in crappie recruits produced per adult. Larval crappie density was treated as an index of reproductive output, and larval Dorosoma and Lepomis, two of the most abundant larval fishes in Illinois reservoirs, could be either competitors with crappie for zooplankton or a source of food for piscivorous crappie juveniles. These factors were added to the Ricker stock-recruitment models for each year class to test if these added variables increased the amount of variation explained by the model. Except for the 2016 Black Crappie year class, density-dependent stock-recruitment functions explained from 43-82% of recruitment variation, with both species exhibiting similar levels of density dependence. Both species, especially White Crappie, exhibited increasing recruitment with increasing stock abundance. This positive relationship between potential spawners and recruitment highlights the importance of appropriate harvest regulations for protecting a sufficient number of adults to maintain populations’ natural regenerative processes. There was also evidence that density-dependent processes limited recruitment past threshold stock sizes. Two of the most supported models included negative effects of conspecific larval density (2017 White Crappie year class) and density of larval Lepomis species (2015 Black Crappie year class), demonstrating the potential for recruitment to be limited by competitive interactions. In contrast to Black Crappie, the most supported models of White Crappie recruitment contained positive relationships with larval Lepomis. White Crappie’s earlier propensity for piscivory than Black Crappie (Ellison 1984), and therefore the greater importance of fish prey in White Crappie than Black Crappie diet, may explain the difference between these two species in the relationship of their recruitment to larval Lepomis density. Longer time series and more detailed examination of daily growth rates and foraging performance during early life stages should provide mechanistic insights into the recruitment relationships revealed by these analyses. In Job 105.1, we have continued to evaluate electrofishing power delivery and sampling efficiency of Smith Root and ETS electrofishing control units as part of a field experiment that was initiated during May 2018 and will run through October 2019. To control for variation in 10 shoreline habitat sampled, fish assemblages, and specific conductivity that may be encountered across different lakes, we have conducted all sampling in Lake Shelbyville, IL. Three electrofishing treatments are being evaluated. The first treatment consists of electrofishing with an ETS MBS-1D electrofisher set to a power goal based on temperature and conductivity of the local environment. The second treatment uses a Type VI-A electrofisher with its DC voltage selection set to 177 DC V, which based on previously collected data, is closest to the output of the standardized ETS unit within Lake Shelbyville (~ 180 V). The third treatment uses a Type VI-A electrofisher with its voltage output selection set to 354 DC V, representing a higher power setting that may be used with this control box. Three 15-minute electrofishing transects are conducted with each treatment at three fixed sites that are sampled monthly from May through October of each year using the same boat (cathode), 6500W generator, and anode array. The driving style, driver, and single dipnetter have been kept consistent for each treatment. As of July 2018, we have completed three months of sampling for a total of 27 electrofishing transects. Analyses of catch data will be completed after one full year of sampling (i.e., when all sites have been sampled with each gear twice). Recommendations on the use of different DC electrofishers and standardized sampling with pulsed DC electrofishing in Illinois will be made in future segments.
Original languageEnglish (US)
PublisherIllinois Natural History Survey
StatePublished - Aug 2018

Publication series

NameINHS Technical Report 2018 (25)


  • INHS


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