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
