Factors Influencing Largemouth Bass Recruitment: Implications For The Illinois Management And Stocking Program

During the past segment, all activities outlined in the annual work plan were accomplished and within the specified budget. The goal of this study is to develop management strategies that maximize growth, recruitment, and harvest of largemouth bass Micropterus salmoides in Illinois impoundments. Largemouth bass are frequently stocked in many Illinois impoundments to compensate for variable recruitment. Even so, the long-term contribution of stocked fish to recruitment and harvest of natural bass populations is unknown and we are addressing these questions. In addition, information on the importance of rearing technique, size of stocked fish, forage base, cover, resident predators, physical-chemical conditions, and stocking stress in determining largemouth bass stocking success is needed to optimize use of hatchery produced fish. Because stocking is only one of several management options for this species, it is critical that additional information on factors limiting recruitment processes be identified.There was no new activity in Job 101.1 as final recommendations were presented in previous reports. In Job 101.2, we continued our evaluation of stocking success of largemouth bass. We conducted additional dataanalysis ina study comparing intensive and extensive rearing techniques. Intensively reared fish were raised in raceways and fed pellets, whereasextensively reared fish were raised in ponds and fed zooplankton and minnows. Extensivelyreared fish experienced better survival through the spring following stocking, but by the following fall (age-1) there was no difference in abundance between the two rearing techniques. We observed a high level of variation inthe number of fish producedinthe rearing ponds. Cost of rearing was much higher for the extensively reared fish for both hatchery ponds and lake side rearing facilities. Higher initial survival and larger size in the fall of extensively reared fish initially appears to justify the added cost. However, long term survival was low for both rearing types and very few stocked fish were recruited to the fishery. In this segment, we also continued to evaluate different stocking techniques to improve survival of stocked largemouth bass. Three lakes were stocked with largemouth bass, with half the fish stocked at the boat ramp and half dispersed throughout the lake and into woody or vegetated habitat. Very few stocked fish have been recaptured from any stockings conducted thus far regardless of method. We plan to continue additional stockings and adjust stocking time to minimize high temperatures and potential related mortality. CPUE of stocked fish in this experiment has been lower than observed in stockings conducted asprevious partsof this project and we hope to observe greater survival in the future in order to evaluate the success of these two stocking strategies.In Job 101.3, we evaluated the survival and reproductive success of stocked largemouth bass relative to resident populations. To determine the contribution of stocked fish, the MDH B2B2 allele was used as a genetic tag for fingerlings stocked into six study lakes. Once these fish were part of the reproducing population, it was possible to assess the reproductive success and recruitment of these stocked fish in five of the six lakes by comparing the pre-stocking with post stocking MDH B2 allele frequencies. We also looked at lake size and resident bass CPUE as a possible factors that may have influenced reproductive success. Stocked fish survival to adulthood was variable in the five study lakes, ranging from less than 10% to around 35%. Contribution of stocked fish to reproduction was also variable and was higher in small lakes than in larger ones. The density of resident bass as measured by CPUE had no relationship to the contribution of stocked bass reproduction in the lakes that we studied. Based on the proportion of stocked adults in the populations we could predict the change in the frequency of the MDH B2 allele to determine how reproductive success of stocked fish compared to wild fish. We found that reproductive success of stocked fish was similar to wild fish. Our results indicate that stocking is most likely to be successful in small lakes and that the genetic influence of stocked fish will persist in successive generations. In future reports, we will examine how prey availability could affect stocked largemouth bass condition and ability to secure good nesting sites differently than wild fish. In Job 101.4, we continued a multi lake experiment examining the influence of vegetation on largemouth bass recruitment. Lakes were divided into treatments by the vegetation management strategy. Two lakes (Stillwater and Airport) were treated for vegetation to reduce the vegetation present and yield more intermediate vegetation densities. The vegetation treatments were initiated in this segment and have been successful at reducing vegetation in Stillwater Lake, but not Airport Lake. Two lakes (Paradise and Dolan) experienced management to increase vegetation. Vegetation planting was initiated in 2008in Lake Paradiseand planting efforts continued in this segment. We areevaluating the success of different species of vegetation and the size of cage used. American pondweed has shown the greatest long-term survival and the large cages have been most effective in producing vegetation. In this segment, American pondweed was planted in 5 additional cages and a number of cages were expanded to promotethe spread of successful cages. We also evaluated fish and invertebrate communities associated with vegetated and non-vegetatedcages and observed higher densities of both fish and invertebrates in vegetated cages. Rehabilitation at Dolan Lake has continued to yield higher vegetation and reduced gizzard shad and carp numbers. There is some evidence of gizzard shad populations rebounding. Four lakes with experimental treatments and 7control lakes were monitored for fish populations, vegetation densities, and prey organisms and will be compared through time as the management experiment continues.CPUE of young of year largemouth bass was higher in lakes with greater vegetation densities, but differences were not significant. The density of larval gizzard shad was significantly correlated with the proportion of lake area and perimeter that was vegetated. No other lake conditions that were measured were related to vegetation density. We will continue to monitor vegetation, fish, and prey communities in the 11 research lakes to evaluate the role of vegetation management to increase largemouth bass recruitment.In this segment, we also continuedto examine patterns in abundance of young-of-year largemouth bass, other fish species, and associated biotic communities a mong vegetated, woody, and open lakeshore habitat types in two Illinois lakes. While we did not find significant differences in age-0 largemouth bass densities among the microhabitat types sampled in our enclosure surveys, we did find significant differences in the community composition and abundance of potentially important prey items (juvenile sunfishes, caddisflies, chironomids, stoneflies and cyclopoid copepods). Increases in abundance of potential invertebrate and fish prey in vegetated and wooded sites supports the idea that these habitats are important sources of littoral productivity. There is potential for dam escapement to influence largemouth bass recruitment. To assess dam escapement, we sampled downstream of the dam on two reservoirs, Ridge Lake and Forbes Lake via backpack electrofishing and seines. Some largemouth bass were observed in sampling below the dam at both Forbes and Ridge Lake following high water events however there were few fish in all sampling. The assessment of dam escapement is in the very early stages of implementation and evaluation and much more data is needed to draw conclusions about the effect of escapement on largemouth bass populations and recruitment. Additional data will be collected so that a baseline can be established in order to compare largemouth bass numbers after an increased discharge event to largemouth bass numbers during low flow periods. There is potential for angling to have a large influence on largemouth bass populations. Competitive tournament fishing for black bass has grown rapidly over the past several years. Previous work has shown high levels of mortality associated with these tournaments in other parts of the United States. However, little is known about the effects of tournaments on largemouth bass recruitment. In Job 101.5, we continued to examine effects of tournaments for largemouth bass. In this segment, we also continued monitoring largemouth bass spawning activities at Lincoln Trail Lake. Water clarity limited our ability to identify largemouth bass nests in spring 2011. We will continue to evaluate nesting activity, nest guarding behavior, vulnerability to angling, and nest predation in future segments. In this segment, we continued to conduct largemouth bass tournaments in alternating years on Ridge Lake to evaluate their effect on recruitment. A series of spring tournaments were conducted in 2007 and 2010 and largemouth bass populations were compared among tournament and non-tournament years. Initial results show no differences in recruitment between tournament and non-tournament years. In addition, no changes were observed in adult largemouth bass abundance or size structure. These results are preliminary and additional years will be needed to evaluate treatment effects. We are continuing a pond experiment examining the population effects of tournament angling during the spawning season on largemouth bass recruitment. In the current segment, we initiated the second year of the two-year study. Results from the first year indicate that tournament angling has a moderate effect on largemouth bass recruitment in terms of numbers, and a rather large effect on young-of-year largemouth bass biomass. After adjustment for summer zooplankton abundance, which was a significant covariate for largemouth bass recruitment, ponds in which tournament angling was conducted had approximately 22% less recruits and 64% less young-of-year biomass than control ponds. In the future segment, we will include data from the second year to strengthen results. In this segment we also continued to evaluate tournament activity on nine Illinois lakes as well as 5 control lakes with no tournaments. Tournament data was used to calculate total tournament angler hours per acre as well as catch rates and statistics on the sizes and types of tournaments on each lake. We evaluated the largemouth bass population in each lake by performing electrofishing transects in the spring. CPUE of young-of-year largemouth bass and largemouth bass over 14 inches was not correlated with tournament pressure (angler hours/acre). The mean number of fish weighed in at a tournament was correlated with CPUE of largemouth bass over 14 inches and was also correlated with lake size. Tournament lakes did not have reduced recruitment when compared to lakes with no tournament angling. Tournament lakes had higher CPUE of largemouth bass larger than 14 inches than control lakes, but it is difficult to separate the effects of tournaments from the size of the lake and the fact that tournaments may target lakes with more abundant adult largemouth bass. We will continue to collect tournament and largemouth bass population data in future segments to further evaluate and understand how tournaments influence largemouth bass populations. In Job 101.6, a portion of Clinton Lake that was closed to fishing was sampled to continue assessment of the effects of a refuge on largemouth bass populations. Electrofishing samples yielded a higher abundance of adult largemouth bass in the refuge than in the main lake. No increase in the number of largemouth bass has been observed throughout the lake. Sampling will continue at Clinton Lake to monitor largemouth bass populations for changes resulting from the refuge. We also continued sampling Otter Lake as an additional location to evaluate refuges. Electrofishing and seine samples were conducted in two refuge sites as well as three control sites. The refuge was closed to fishing in June 2010 and we initiated sampling for post refuge conditions. We also began assessing effects of harvest regulations on largemouth bass populations. In this segment, we expanded our database of lakes using the Fisheries Analysis System (FAS) containing electrofishing data from 2000-2007 collected by DNR biologists. We grouped lakes by regulation type into 7 groups; Bag by Size(Bag limit above and below a specified size), Catch-and Release (no harvest allowed), Standard (14” length limit, 6 fish creel), Lowered Bag (14” length limit, 14” length limit, 6 fish bag limit), Raised Length/Low Bag (>14” length limit, <6 fish bag limit), No Length (No minimum size limit), and Slot (no fish harvest slot). We compared catch rates of young-of-year and adults (greater than 14 inches), memorable (greater than 510 mm), and proportion stock density (PSD). Lakes with slot limit regulations had the highest CPUE of young-of-year, total, and memorable sized largemouth bass. No other significant differences existed among groups. In future segments, we will combine FAS, INHS sampling and creel data to further evaluate regulations and how they affect angler catch rates. These data can then be used to guide future discussions about various management experiments that might be implemented.Division of Fisheries, Illinois Department of Natural Resources Grant/Contract No: F-135-Runpublishednot peer reviewe

Foraging ecology of two piscivores in woody habitat and effects of their introduction on lake ecosystems

Predation is a major ecological force affecting the abundance and species composition of natural communities. Predation from piscivorous fish is a strong driver of these patterns in freshwater aquatic communities. My research is directed at testing whether the introduction and augmentation of piscivore populations, as well as the alteration of littoral habitats, in Illinois lakes affects the consequences of predation for other ecologically and recreationally important species in these ecosystems. Some studies in lentic ecosystems have found large effects of introducing piscivores to systems that previously lacked them, as well as, to the artificial enhancement of piscivore populations. While the evidence for such “trophic cascades” is plentiful, a large body of subsequent research has suggested that certain properties of lakes found in lower latitude systems in the central and southern United States may buffer these systems from cascading effects of piscivore manipulations. Therefore, there is a need to test the generality of cascading trophic interactions in these lower latitude lentic ecosystems. Thus, in chapter 1 I tested for the effects of supplemental piscivore enhancements on the food webs of several Illinois lakes in a series of whole-lake experiments incorporating unmanipulated control systems. I found that piscivore enhancements in Illinois lakes did not cause the predicted pelagic food web changes predicted by the traditional trophic cascade theory; however, there was a significant effect upon littoral macroinvertebrates. This effect was driven by a reduction in the abundance of small bodied littoral fishes (primarily juvenile bluegills) after the initiation of supplemental largemouth bass stocking. My results highlight the importance of system-specific characteristics in determining the effects of piscivore enhancement measures. In addition to piscivore enhancement, there is a need to better understand the effects of introducing new piscivore species. Previous studies suggest that the introduction of new species can drive a nearly limitless array of food web consequences, with the most common including direct and indirect interactions between top predators and changes in prey mortality rates. In a controlled experimental design, I tested for changes in population characteristics including size structure, condition, and relative abundance of several ecologically and recreational important resident fish species in response to muskellunge introduction across several Illinois lakes. I found that contrary to popular concerns, the dominant resident piscivore largemouth bass generally increased in relative abundance in response to muskellunge introduction. I also found few effects of introduced muskellunge on common prey species, with the exception of Pomoxis spp., which exhibited increases in size structure and/or decreases in relative abundance. My results indicate that the current trend of muskellunge introduction in lower Midwestern lakes does not appear to be significantly harming resident populations; however, much future work remains in this area. Physical habitat can be an important determinant of the strength of piscivory on freshwater fish populations. Thus, I conducted a manipulative laboratory experiment to test for the effects of coarse woody habitat complexity on the piscivore-prey interaction between four species with contrasting predatory and anti-predatory behavioral traits. I found that woody habitat in the form of deadfall conifer branches did not reduce total prey fish mortality rates inflicted by piscivores in experimental arenas. I did find an increase in mortality rate with increasing coarse woody habitat complexity for an obligate shoaling prey fish. Furthermore, there were significant effects of coarse woody habitat complexity on foraging efficiency of piscivores, which may influence metabolic costs and therefore piscivore energy balance (as net energy for reproduction and growth is equal to energy consumption minus losses due to excretion, egestion and metabolism). Collectively, my results suggest that coarse woody habitat may influence piscivore-prey interactions principally through behavioral mechanisms and subsequent effects of behavior on piscivore energy balance as defined above

Factors Influencing Largemouth Bass Recruitment: Implications for the Illinois Management and Stocking Program Annual Progress Report July 1, 2009 to June 30, 2010

The goal of this study is to develop management strategies that maximize growth, recruitment, and harvest of largemouth bass Micropterus salmoides in Illinois impoundments. Largemouth bass are frequently stocked in many Illinois impoundments to compensate for variable recruitment. Even so, the long-term contribution of stocked fish to recruitment and harvest of natural bass populations is unknown and we are addressing these questions. In addition, information on the importance of rearing technique, size of stocked fish, forage base, cover, resident predators, physical-chemical conditions, and stocking stress in determining largemouth bass stocking success is needed to optimize use of hatchery produced fish. Because stocking is only one of several management options for this species, it is critical that additional information on factors limiting recruitment processes be identified.During the past segment, all activities outlined in the annual work plan were accomplished and within the specified budget. The goal of this study is to develop management strategies that maximize growth, recruitment, and harvest of largemouth bass Micropterus salmoides in Illinois impoundments. Largemouth bass are frequently stocked in many Illinois impoundments to compensate for variable recruitment. Even so, the long-term contribution of stocked fish to recruitment and harvest of natural bass populations is unknown and we are addressing these questions. In addition, information on the importance of rearing technique, size of stocked fish, forage base, cover, resident predators, physical-chemical conditions, and stocking stress in determining largemouth bass stocking success is needed to optimize use of hatchery produced fish. Because stocking is only one of several management options for this species, it is critical that additional information on factors limiting recruitment processes be identified.Division of Fisheries, Illinois Department of Natural Resources Federal Aid Project F-135-R-12unpublishednot peer reviewe

Evaluation of Growth and Survival of Different Genetic Stocks of Muskellunge: Implications for Stocking Programs in Illinois and the Midwest.

Muskellunge Esox masquinongy are an important sportsfish that are commonly stocked throughout Illinois and much of the Midwestern United States. In Illinois, as in many other states, the demand for these fishes far exceeds the supply. Stocking has become the primary management tool for establishing and maintaining muskellunge populations. The high costs associated with producing these fishes create the need for efficient management practices. Previous research efforts have determined the size of fish and timing of stocking to maximize growth and survival. However, additional information on muskellunge stocking strategies is needed. Specifically, more biological data on different genetic stocks of muskellunge is needed to determine the best population to stock in a particular body of water to maximize growth and survival. In addition little research has focused on the response of fish communities and lake ecosystems to muskellunge stocking. As muskellunge increase in popularity and stocking becomes more widespread, potential impacts of muskellunge introduction on existing fisheries and aquatic communities must be considered. Morphological and geographic characteristics have suggested multiple distinct groups of muskellunge. More recently, genetic analysis identified several different genetic stocks of muskellunge (Ohio River drainage, Upper Mississippi River drainage, and the Great Lakes drainage stocks), each with multiple populations. Previous work with young-of-year from these populations found differences in growth and food consumption as a function of temperature. As a trophy species, anglers and managers are interested in utilizing populations of fish that grow the fastest, live longest, and obtain a largest maximum size. Because muskellunge populations are either not naturally found or have been extirpated in many Illinois lakes and reservoirs, it is not clear which population to use in stocking efforts. The muskellunge population currently used as brood stock for the stocking program in Illinois is of an unknown origin and may be made up of several different populations. Muskellunge stocks from various populations may perform differently in Illinois waters in terms of growth and survival. Additional information is needed on differences in growth and survival among stocks in waters at varying latitudes in Illinois before management recommendations can be made on which stock is most appropriate. Determining which stock has the highest levels of growth and survival under the various conditions found in Illinois waters will increase stocking success and angler satisfaction. The first two jobs of this study examine differences in growth and survival among different stocks of muskellunge in order to make recommendations regarding stocking in Illinois. Previous research on interactions of muskellunge with the aquatic community has been sparse or generally inconclusive. In addition, the existing literature on muskellunge diet focuses on natural lakes in northern states which limit the utilit y o f this informat ion to managers in the lower Midwest. A few studies exist in the literature which report fishery effects of muskellunge introductions. For example one study attributed muskellunge with the decline of largemouth bass populations in two Wisconsin lakes and another study documented a decline in black crappie and white sucker populations in Iron Lake, Michigan in response to muskellunge stocking. There also exists a conflicting body of literature on interactions between muskellunge and northern pike. The utility of these studies to inform managers about the potential effects of muskellunge introduction in lakes of the lower Midwest is limited by a lack of replication or adequate comparison to control systems. The third job o f this study will provide a rigorous evaluation of the diet and community effects of muskellunge across a number of Illinois lakes in order to inform managers about the potential effects of muskellunge introductions. During segment six, all activities outlined in the annual work plan were accomplished and were completed within the specified budget. During this segment, two jobs related to 6 muskellunge stock evaluation and one job related to food habits and effects of muskellunge introduction were completed. In previous segments of the study, we compared initial growth and survival of muskellunge from the Upper Mississippi River drainage stock, the Ohio River drainage stock, and the Illinois North Spring Lake progeny in two Illinois lakes. During this segment muskellunge fingerlings from four sources were introduced into Pierce Lake, Lake Mingo, and Sam Dale Lake at rates ranging from 3.3 ñ 4.9 fish per hectare during fall 2007. Electrofishing was conducted during fall 2007 and spring 2008, and combined with modified fyke net surveys during spring 2008 in all lakes. Across years and lakes, the Ohio River drainage stock and the Illinois population appear to have similar growth rates; both consistently higher than the Upper Mississippi River drainage stock. Results from lake introductions suggest that after the first summer, the Ohio River drainage stock and Illinois population typically have similar survival and both are higher than the Upper Mississippi River drainage stock. These, and future introductions will need to be monitored over additional years to further assess long-term growth and survival differences among stocks. Muskellunge diet samples were collected from 280 fish across 4 Illinois lakes. These lakes included Lake Shelbyville, Lake Mingo, Ridge Lake, and Pierce Lake. Diet analysis showed that where present, gizzard shad dominated muskellunge diet in both numbers and biomass across all size classes and seasons. Diet of muskellunge in Ridge Lake consisted primarily of bluegill although a small percentage of the samples contained largemouth bass. Diet in this lake is limited by low species diversity and the lack of preferred prey such as gizzard shad. Diet breadth was highest in Lake Shelbyville likely due to its large size and diverse fish community. Preliminary results from diet analysis indicate that where available gizzard shad are the primary forage of muskellunge in Illinois lakes followed by bluegill. While this data provides a preliminary analysis of muskellunge diets in these lakes over the past year, more data is required to adequately characterize annual and seasonal fluctuations occurring over time. Specifically it is unclear how food habits of muskellunge may change in response to annual fluctuations in prey availability or whether consistent seasonal trends are present. In the current segment we began examining two sets of analyses on the community and fishery effects of muskellunge introductions. The first analysis utilizes a community data set collected as part of previous Federal Aid in Sport Fish Restoration Projects (F-135-R, Factors influencing largemouth bass recruitment and stocking and F-128-R, Quality management of bluegill populations). Data from each trophic level including fish communities, zooplankton, larval fish, benthic macroinvertebrates, and nutrients has been collected on a series of control lakes as well as lakes Mingo and Ridge which have received muskellunge stockings. Lake Mingo has received muskellunge since fall of 2002 and Ridge Lake has been stocked since fall 2006. Data from Mingo and Ridge Lake will be compared to control lakes before and after muskellunge introduction to determine if these stockings cause any changes in the aquatic communities of these two lakes. Preliminary results indicate that largemouth bass and bluegill abundance have not been negatively affected by muskellunge stocking in Lake Mingo. In addition gizzard shad abundance has remained relatively constant although the average size of gizzard shad sampled in Lake Mingo has increased relative to controls. The increase in size structure of gizzard shad in Lake Mingo may be due to increased predation pressure on smaller size classes by juvenile muskellunge. The second set of analyses on effects of muskellunge stocking involves a larger sample of lakes taken from the state FAS database. Examination of muskellunge stocking records has identified several lakes that received concurrent initial stockings of muskellunge. This analysis 7 will focus specifically on fish communities and creel data comparing trends before and after muskellunge introduction with a series of control lakes. Controls will be selected by choosing lakes which have similar geographic, physiochemical, morphometric and fishery characteristics to lakes receiving muskellunge stockings. This analysis will provide a more rigorous examination of muskellunge effects on existing fisheries due to a larger number of replicate lakes. In future years we will continue to monitor populations of muskellunge in lakes Mingo, Pierce and Sam Dale to evaluate long term growth and survival differences between stocks and populations. The results obtained from initial years will be combined with those from future years to identify the long-term growth and survival differences among genetic stocks of muskellunge. Results will be used to develop guidelines for future muskellunge stockings that maximize growth, survival, and angler satisfaction in lakes throughout Illinois. As the management of muskellunge fisheries improves due to increased understanding of intraspecific variation, the effects of these highly predacious fishes on the existing aquatic community also needs to be considered. In future segments we will continue to examine the food habits and effects of muskellunge on existing and native communities. This information, combined with an increased understanding of appropriate stocks, will contribute to a more informed and holistic approach to muskellunge management in Illinois and the lower Midwest.Division of Fisheries Illinois Department of Natural Resourcesunpublishednot peer reviewe

Evaluation Of Growth And Survival Of Different Genetic Stocks Of Muskellunge: Implications For Stocking Programs In Illinois And The Midwest

Muskellunge Esox masquinongy are an important and increasingly popular sportfish that are commonly stocked throughout Illinois and much of the Midwestern United States. Stocking has become the primary management tool for establishing and maintaining muskellunge populations in Illinois and across the Midwestern United States. Great demand for these fish and the high costs associated with producing them create the need for efficient management practices. Previous research efforts have determined the size of fish and timing of stocking to maximize growth and survival. However, additional information on muskellunge stocking strategies is needed. More data on performance of different genetic stocks of muskellunge, both within and outside their native range, is needed to determine the best population to stock in a particular body of water to maximize growth and survival. Little research has focused on the response of fish communities and lake ecosystems to muskellunge stocking. As the muskellunge range is artificially expanded by more widespread stocking it becomes increasingly important to understand the potential impacts of muskellunge introduction on existing fisheries and aquatic communities. Morphological and geographic characteristics have suggested multiple distinct groups of muskellunge. More recently, genetic analysis identified several different genetic stocks of muskellunge (Ohio River drainage, Upper Mississippi River drainage, and the Great Lakes drainage stocks), each with multiple populations. Genetically distinct stocks are quickly becoming the new operational unit in fisheries management to optimize performance regionally. Understanding stock differentiation becomes increasingly important with a trophy species like muskellunge where anglers and managers are interested in utilizing populations of fish that grow the fastest, live longest, and obtain a largest maximum size. Because muskellunge populations are either not naturally found or have been extirpated in many Illinois lakes and reservoirs, it is not clear which population to use in stocking efforts. The muskellunge population currently used as brood stock for the stocking program in Illinois is of an unknown origin and may be made up of several different populations. Additional information is needed on differences in growth and survival among stocks in waters at varying latitudes in Illinois before management recommendations can be made on which stock is most appropriate. The first two jobs of this study examine differences in growth and survival among different stocks of muskellunge in order to make recommendations regarding stocking in Illinois. Previous research on interactions of muskellunge with the rest of the aquatic community has been sparse and generally inconclusive. In addition, the existing literature on muskellunge diet focuses on natural lakes in northern states, which limits the utility of this information to managers in the lower Midwest. Few studies exist in the literature that report fishery and community effects of muskellunge introductions. One study attributed muskellunge with the decline of largemouth bass populations in two Wisconsin lakes and another study documented a decline in black crappie and white sucker populations in Michigan in response to muskellunge stocking. The utility of these studies to inform managers about the potential effects of muskellunge introduction in lakes of the lower Midwest is limited by a lack of replication or adequate comparison to control systems. The third job of this study provides a rigorous evaluation of the diet and community effects of muskellunge across a number of Illinois lakes in order to inform managers about the potential effects of muskellunge introductions. During segment nine, all activities outlined in the annual work plan were accomplished and were completed within the specified budget. During this segment, two jobs related to muskellunge stock evaluation and one job related to food habits and effects of muskellunge introduction were continued. In previous segments of the study, we compared initial growth and survival of muskellunge from the Upper Mississippi River drainage stock, the Ohio River drainage stock, and the Illinois North Spring Lake progeny in three Illinois lakes. In this segment population sampling by electrofishing was conducted during fall 2010 and spring 2011. These data were combined with modified fyke net surveys during spring 2011.Across years and lakes, the Ohio River drainage stock and the Illinois population generally appear to have similar growth rates through age-1. Through adulthood growth of the Upper Mississippi River drainage stock appears to be somewhat higher based on limited samples thus far that need to continue to be expanded in the future. Analysis of body morphology indicates that fish from the Upper Mississippi River drainage are consistently more lean than those of the other stocks. Results thus far from lake introductions suggest that after the first summer following stocking, the Ohio River drainage stock and Illinois population typically have similar survival and both are higher than the Upper Mississippi River drainage stock. This pattern led to consistently lower survival of Upper Mississippi River drainage stock year classes to adulthood. The Ohio River drainage stock and Illinois population show similar survival both to adulthood and annually through adult age classes. These introductions will need to be monitored over additional years to further assess potential differences in long-term growth, maximum length, and survival differences among stocks. Muskellunge diet samples were collected from fish across 7 Illinois lakes from fall 2007 to spring 2011. These lakes included Lake Shelbyville, Lake Mingo, Ridge Lake, Pierce Lake, Lake of the Woods, Otter Lake, and Sam Dale Lake. Thus far food habits data has shown that where present, gizzard shad dominate muskellunge diet in both numbers and biomass across all size classes and seasons. Gizzard shad are not present in Ridge Lake where muskellunge diets consist primarily of bluegill, although a small percentage of the samples contained largemouth bass. Results thus far from diet analysis indicate that where available gizzard shad are the primary forage of muskellunge in Illinois lakes followed by bluegill. This pattern is generally consistent between seasons, although there is some evidence that bluegill become a more important prey item in the spring. While this data provides a preliminary analysis of muskellunge diets in these lakes, more data is required to adequately characterize annual and seasonal fluctuations occurring over time. It is unclear how food habits of muskellunge may change in response to annual fluctuations in prey availability or whether size related trends are present. In the current segment we continued two sets of analyses focused on the community and fishery effects of muskellunge introductions. The first analysis expands a previously reported community analysis incorporating a data set collected as part of previous Federal Aid in Sport Fish Restoration Projects (F-135-R, Factors influencing largemouth bass recruitment and stocking and F-128-R, Quality management of bluegill populations). Data from multiple trophic levels including fish communities, zooplankton, nutrients, larval fish and benthic macroinvertebrate densities have previously been compared between lakes Mingo and Ridge and two reference lakes. In this segment we included data on larval fish and macroinvertebrate density from 2010.Lake Mingo has received muskellunge since fall of 2002 and Ridge Lake has been stocked since fall 2006. Data from Mingo and Ridge Lake is being compared to reference lakes before and after muskellunge introduction to determine if these stockings cause any changes in the aquatic communities of these two lakes. Preliminary results indicate that muskellunge stocking in Lake Mingo or Ridge Lake has not negatively affected largemouth bass and bluegill abundance and no significant effects on other parts of the aquatic food web have been detected. The second set of analyses on effects of muskellunge stocking will involve a larger sample of lakes taken from the state Fishery Analysis System (FAS) database. Examination of muskellunge stocking records has identified a series of lakes that received concurrent initial stockings of muskellunge. To ensure that lakes selected for analysis have substantial muskellunge populations, we are selecting lakes where stockings have been successful based on both standardized electrofishing and spring trap netting surveys. This analysis will focus specifically on fish communities comparing trends before and after muskellunge introduction with a series of reference lakes. Reference lakes have been selected, which have similar geographic, physiochemical, morphometric and fishery characteristics to lakes receiving muskellunge stockings. This analysis will provide a more rigorous examination of muskellunge effects on existing fisheries due to a larger number of replicate lakes. Our results suggest that across 8 lakes in a time series ranging from 3-10 years after muskellunge introduction abundance of largemouth bass increased while no negative effects on size structure were observed. With the exception of decreasing white crappie abundance, muskellunge introductions had either nonnegative or positive effects on size structure and abundance of sport and prey fishes including bluegill, redear sunfish and crappie. Muskellunge introductions appear to have very little impact on common carp or gizzard shad populations. In future years we will continue to monitor populations of muskellunge in lakes Mingo, Pierce and Sam Dale to evaluate long-term growth and survival differences between stocks and populations. The results obtained from initial years will be combined with those from future years to identify the long-term growth and survival differences among genetic stocks of muskellunge. These long-term data will be used to examine attributes such as longevity, maximum size-at-age, and size-at-maturity. Results will be used to develop guidelines for future muskellunge stockings that maximize growth, survival, and angler satisfaction in lakes throughout Illinois. As the management of muskellunge fisheries improves due to increased understanding of intraspecific variation, the effects of these highly predacious fishes on the existing aquatic community also needs to be considered. In future segments we will continue to examine the food habits and effects of muskellunge on existing fish populations. This information, combined with an increased understanding of appropriate stocks, will contribute to a more informed and holistic approach to muskellunge management in Illinois and the lower MidwestDivision of Fisheries Illinois Department of Natural Resourcesunpublishednot peer reviewe

Evaluation Of Growth And Survival Of Different Genetic Stocks Of Muskellunge: Implications For Stocking Programs In Illinois And The Midwest

Muskellunge Esox masquinongy are an important sportfish that are commonly stocked throughout Illinois and much of the Midwestern United States. In Illinois, as in many other states, the demand for these fishes far exceeds the supply. Stocking has become the primary management tool for establishing and maintaining muskellunge populations. The high costs associated with producing these fishes create the need for efficient management practices. Previous research efforts have determined the size of fish and timing of stocking to maximize growth and survival. However, additional information on muskellunge stocking strategies is needed. Specifically, more biological data on different genetic stocks of muskellunge is needed to determine the best population to stock in a particular body of water to maximize growth and survival. In addition little research has focused on the response of fish communities and lake ecosystems to muskellunge stocking. As muskellunge increase in popularity and stocking becomes more widespread, potential impacts of muskellunge introduction on existing fisheries and aquatic communities must be considered. Morphological and geographic characteristics have suggested multiple distinct groups of muskellunge. More recently, genetic analysis identified several different genetic stocks of muskellunge (Ohio River drainage, Upper Mississippi River drainage, and the Great Lakes drainage stocks), each with multiple populations. As a trophy species, anglers and managers are interested in utilizing populations of fish that grow the fastest, live longest, and obtain a largest maximum size. Because muskellunge populations are either not naturally found or have been extirpated in many Illinois lakes and reservoirs, it is not clear which population to use in stocking efforts. The muskellunge population currently used as brood stock for the stocking program in Illinois is of an unknown origin and may be made up of several different populations. Additional information is needed on differences in growth and survival among stocks in waters at varying latitudes in Illinois before management recommendations can be made on which stock is most appropriate. The first two jobs of this study examine differences in growth and survival among different stocks of muskellunge in order to make recommendations regarding stocking in Illinois. Previous research on interactions of muskellunge with the aquatic community has been sparse and generally inconclusive. In addition, the existing literature on muskellunge diet focuses on natural lakes in northern states, which limits the utility of this information to managers in the lower Midwest. Few studies exist in the literature, which report fishery effects of muskellunge introductions. One study attributed muskellunge with the decline of largemouth bass populations in two Wisconsin lakes and another study documented a decline in black crappie and white sucker populations in Iron Lake, Michigan in response to muskellunge stocking. The utility of these studies to inform managers about the potential effects of muskellunge introduction in lakes of the lower Midwest is limited by a lack of replication or adequate comparison to control systems. The third job of this study will provide a rigorous evaluation of the diet and community effects of muskellunge across a number of Illinois lakes in order to inform managers about the potential effects of muskellunge introductions. During segment seven, all activities outlined in the annual work plan were accomplished and were completed within the specified budget. During this segment, two jobs related to muskellunge stock evaluation and one job related to food habits and effects of muskellunge introduction were completed. In previous segments of the study, we compared initial growth and survival of muskellunge from the Upper Mississippi River drainage stock, the Ohio River drainage stock, and the Illinois North Spring Lake progeny in two Illinois lakes. In this segment electrofishing was conducted during fall 2008 and spring 2009, and combined with modified 6fyke net surveys during spring 2009. Across years and lakes, the Ohio River drainage stock and the Illinois population appear to have similar growth rates; both consistently higher than the Upper Mississippi River drainage stock. Results from lake introductions suggest that after the first summer, the Ohio River drainage stock and Illinois population typically have similar survival and both are higher than the Upper Mississippi River drainage stock. These introductions will need to be monitored over additional years to further assess long-term growth and survival differences among stocks. From summer 2007 to spring 2009 muskellunge diet samples have been collected from 591 fish across 6 Illinois lakes. These lakes included Lake Shelbyville, Lake Mingo, Ridge Lake, Pierce Lake, Lake of the Woods and Sam Dale Lake. Analysis of this data has shown that where present, gizzard shad dominated muskellunge diet in both numbers and biomass across all size classes and seasons. Diet of muskellunge in Ridge Lake consisted primarily of bluegill although a small percentage of the samples contained largemouth bass. Diet in this lake is limited by low species diversity and the absence of gizzard shad. Results thus far from diet analysis indicate that where available gizzard shad are the primary forage of muskellunge in Illinois lakes followed by bluegill. While this data provides a preliminary analysis of muskellunge diets in these lakes, more data is required to adequately characterize annual and seasonal fluctuations occurring over time. Specifically it is unclear how food habits of muskellunge may change in response to annual fluctuations in prey availability or whether consistent seasonal or size related trends are present. In the current segment we continued two sets of analyses focused on the community and fishery effects of muskellunge introductions. The first analysis utilizes a community data set collected as part of previous Federal Aid in Sport Fish Restoration Projects (F-135-R, Factors influencing largemouth bass recruitment and stocking and F-128-R, Quality management of bluegill populations). Data from each trophic level including fish communities, zooplankton, larval fish, benthic macroinvertebrates, and nutrients has been collected on two reference lakes as well as lakes Mingo and Ridge, which have received muskellunge stockings. Lake Mingo has received muskellunge since fall of 2002 and Ridge Lake has been stocked since fall 2006. Data from Mingo and Ridge Lake is being compared to reference lakes before and after muskellunge introduction to determine if these stockings cause any changes in the aquatic communities of these two lakes. Preliminary results indicate that muskellunge stocking in Lake Mingo or Ridge Lake has not negatively affected largemouth bass and bluegill abundance and no significant effects on other parts of the aquatic food web have been detected. The second set of analyses on effects of muskellunge stocking will involve a larger sample of lakes taken from the state Fishery Analysis System (FAS) database. Examination of muskellunge stocking records has identified a series of lakes that received concurrent initial stockings of muskellunge. To ensure that lakes selected for analysis have substantial muskellunge populations, we are comparing catch rates of muskellunge from candidate lakes to catch rates from lakes with known high-density populations (lakes Mingo and Pierce) based on both standardized electrofishing and spring trap netting surveys. This analysis will focus specifically on fish communities comparing trends before and after muskellunge introduction with a series of reference lakes. Reference lakes have been selected, which have similar geographic, physiochemical, morphometric and fishery characteristics to lakes receiving muskellunge stockings. This analysis will provide a more rigorous examination of muskellunge effects on existing fisheries due to a larger number of replicate lakes. Preliminary results based 7on three stocked and two reference lakes suggest that muskellunge introductions are having no effect on the size structure or relative abundance of largemouth bass populations. In future years we will continue to monitor populations of muskellunge in lakes Mingo, Pierce and Sam Dale to evaluate long-term growth and survival differences between stocks and populations. The results obtained from initial years will be combined with those from future years to identify the long-term growth and survival differences among genetic stocks of muskellunge. Results will be used to develop guidelines for future muskellunge stockings that maximize growth, survival, and angler satisfaction in lakes throughout Illinois. As the management of muskellunge fisheries improves due to increased understanding of intraspecific variation, the effects of these highly predacious fishes on the existing aquatic community also needs to be considered. In future segments we will continue to examine the food habits and effects of muskellunge on existing fish populations. This information, combined with an increased understanding of appropriate stocks, will contribute to a more informed and holistic approach to muskellunge management in Illinois and the lower Midwest.Division of Fisheries Illinois Department of Natural Resourcesunpublishednot peer reviewe

Factors influencing largemouth bass recruitment: implications for the Illinois management and stocking program

Division of Fisheries, Illinois Department of Natural Resources Grant/Contract No: Federal Aid Project F-135-R-11The goal of this study is to develop management strategies that maximize growth, recruitment, and harvest of largemouth bass Micropterus salmoides in Illinois impoundments. Largemouth bass are frequently stocked in many Illinois impoundments to compensate for variable recruitment. Even so, the long-term contribution of stocked fish to recruitment and harvest of natural bass populations is unknown and we are addressing these questions. Because stocking is only one of several management options for this species, it is critical that additional information on factors limiting recruitment processes be identified. In addition, information on the importance of rearing technique, size of stocked fish, forage base, cover, resident predators, physical-chemical conditions, and stocking stress in determining largemouth bass stocking success is needed to optimize use of hatchery produced fish.INHS Technical Report Prepared for Division of Fisheries, Illinois Department of Natural Resource

Evaluation Of Growth And Survival Of Different Genetic Stocks Of Muskellunge: Implications For Stocking Programs In Illinois And The Midwest Final Report

This final report summarizes growth and survival comparisons among the three stocks from Mingo, Pierce, and Sam Dale Lakes. All activities outlined in the annual work plans were accomplished and were completed within the specified budget. Two jobs related to muskellunge stock evaluation and one job related to food habits and effects of muskellunge introduction have been completed. In the final report, we compare growth and survival of muskellunge from the Upper Mississippi River drainage stock, the Ohio River drainage stock, and the Illinois North Spring Lake progeny in three Illinois lakes. Populations were sampled by electrofishing and modified fyke net surveys during spring. Data was compiled from all years to describe long-term trends in growth and survival of muskellunge stocks in Illinois. Across years and lakes, the Ohio River drainage stock and the Illinois population generally appear to have similar growth rates through age-1. Few Upper Mississippi River drainage stock were available for growth comparisons and there is a need to continue to collecting these fish in the future. Analysis of body morphology indicates that fish from the Upper Mississippi River drainage are consistently leaner than those of the other stocks. Results from lake introductions suggest that after the first summer following stocking, the Ohio River drainage stock and Illinois population typically have similar rates of survival, both of which are higher than the Upper Mississippi River drainage stock. This pattern led to consistently lower survival of Upper Mississippi River drainage stock year classes to adulthood as well. The Ohio River drainage stock and Illinois population show similar survival both to adulthood and annually through adult age classes. The specific mechanism responsible for differences in survival rate among stocks is still unknown. Year classes will need to be monitored over additional years to further assess potential differences in long-term growth, maximum length, and survival among stocks, particularly in Lake Sam Dale where adult muskellunge from the Upper Mississippi River drainage stock have been recaptured with greater consistency. Growth and survival patterns among stocks through age-1 were also compared in a series of controlled pond studies. Muskellunge from the Ohio River drainage stock, the Upper Mississippi River drainage stock, and the current Illinois brood stock population were used in these comparisons. Overwinter survival was similar among stocks; however, growth varied overwinter, with Ohio River drainage stock muskellunge exhibiting higher growth rates than conspecifics. One-year post-stocking survival was generally similar between the Ohio River drainage stock and the Illinois stock, with both having higher survival than the Upper Mississippi River drainage stock. In experimental ponds, the Ohio River drainage stock grew faster than the Illinois and Upper Mississippi River drainage muskellunge. These survival results were very similar to lake evaluations showing greater survival of Ohio River Drainage and Illinois stock muskellunge than the Upper Mississippi River Drainage stock. Muskellunge diet samples were collected from fish across 7 Illinois lakes from fall 2007 to spring 2012. These lakes included Lake Shelbyville, Lake Mingo, Ridge Lake, Pierce Lake, Lake of the Woods, Otter Lake, and Sam Dale Lake. Thus far food habits data has shown that where present, gizzard shad dominate muskellunge diet in both numbers and biomass across all size classes and seasons. Gizzard shad are not present in Ridge Lake where muskellunge diets consist primarily of bluegill, although a small percentage of the samples contained largemouth bass. Results from diet analysis are conclusive in that where available gizzard shad are the primary forage of muskellunge in Illinois lakes followed by bluegill. This pattern is generally consistent between seasons, although there is some evidence that bluegill become a slightly more important prey item in the spring. While this data provides a preliminary analysis of muskellunge diets in these lakes, more data is required to adequately characterize annual and seasonal fluctuations occurring over time. Specifically it is unclear how food habits of muskellunge may change in response to annual fluctuations in prey availability or whether size related trends are present. Furthermore, more data is needed on muskellunge diet in systems where gizzard shad are not present. This final report summarizes a set of analyses on effects of muskellunge stocking involving a sample of lakes taken from the state Fishery Analysis System (FAS) database. Examination of muskellunge stocking records identified a series of lakes that received concurrent initial stockings of muskellunge. This analysis provides a rigorous examination of muskellunge effects on existing fisheries due to the inclusion of multiple replicate lakes. Our results suggest that across 8 lakes in a time series ranging from 4-10 years after muskellunge introduction abundance of largemouth bass increased while no negative effects on size structure were observed. With the exception of decreasing white crappie abundance, muskellunge introductions had either nonnegative or positive effects on size structure and abundance of sport and prey fishes including bluegill, redear sunfish and crappie. Muskellunge introductions appear to have very little impact on common carp or gizzard shad populations. This final report provides a summary of adult and juvenile muskellunge growth and survival trends observed in Lakes Mingo and Pierce since 2002. Muskellunge stocking in Lake Sam Dale did not begin until 2005. Additional years of sampling will be required to describe patterns of muskellunge survival in Lake Sam Dale. The results of this study will be combined with those from future years to identify the long-term growth and survival differences among genetic stocks of muskellunge. In particular, these long-term data will be used to examine attributes such as longevity, maximum size-at-age, and size-at-maturity. Results of this study can be used to develop guidelines for future muskellunge stockings that maximize growth, survival, and angler satisfaction in lakes throughout Illinois. Understanding intraspecific variation in muskellunge growth rate and survival as well as the effects of these highly predacious fishes on the existing aquatic community contribute to a more informed and holistic approach to muskellunge management in Illinois and the lower Midwest.IDNR Division of Fisheriesunpublishednot peer reviewe

Factors Influencing Largemouth Bass Recruitment Implications for the Illinois Management and Stocking Program

The goal of this study was to develop management strategies that maximize growth, recruitment, and harvest of largemouth bass Micropterus salmoides in Illinois impoundments. Largemouth bass are frequently stocked in many Illinois impoundments to compensate for variable recruitment. Even so, the long-term contribution of stocked fish to recruitment and harvest of natural bass populations is unknown and we addressed these questions. In addition, information on the importance of rearing technique, size of stocked fish, forage base, cover, resident predators, physical-chemical conditions, and stocking stress in determining largemouth bass stocking success is needed to optimize use of hatchery produced fish. Because stocking is only one of several management options for this species, it is critical that additional information on factors limiting recruitment processes be identified.IDNR Division of Fisheriesunpublishednot peer reviewe