The Emiquon Preserve is a restored backwater with variable connectivity to the Illinois River managed by a gated pumping structure. Trends in composition and structure of the Emiquon fish community has been evaluated through standardized monitoring since initial stocking in 2007. However, evaluation of fish vital rates and their response to specific management actions have not been investigated. Our objectives of our study will determine the influence of biotic and abiotic predictors (water elevation, water temperature, vegetation abundance, plankton abundance) on 1.) year class strength using catch curve residuals, 2.) yearly growth using otolith increment width and biochronology, and 3.) growth (individual yearly and cohort specific using length at age and size structure) from largemouth bass, bluegill, and black crappie. We will leverage previously collected sagittae otoliths from 2015 (n=269) and 2016 (n=120) and collect additional structures in 2020 and 2021 to achieve an otolith record dating back to Emiquon’s initial stocking. Fishes will be collected in Spring using LTRM standardized electrofishing (60hz PDC), 10 fish per 10 mm size class for each species (min= 100 per species), and water elevation, water quality, and vegetation abundance will be collected as covariates. Sagittae otoliths will be sectioned, annuli identified and enumerated, and will use catch curves derived from age-length keys generated from standardized monitoring, to calculate catch curve residuals and evaluate year class strength. Additionally, incremental growth (response variable) will be measured and estimated using a linear mixed effects model accounting for variation in individual fish and age at capture to determine annual growth. Correlations for annual growth and year class strength will be tested with biotic and abiotic predictors such as water elevation, water temperature, vegetation abundance, plankton abundance. Determination of these relationships will help guide management actions to determine the effects of water level management on Emiquon sportfish communities.
|Title of host publication
|15th Annual Emiquon Science Symposium
|Published - 2021