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CONFERENCE SCHEDULE UPDATES & CHANGES: As a result of the prolonged government shutdown, we experienced a number of cancellations and changes to the schedule. Cancellations and changes are listed here (as of January 26, 2019). 
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Tuesday, January 29 • 10:20am - 10:40am
(FISHERIES: GREAT LAKES 2) Evaluating the Influence of Past and Current Environments on Lake Erie Walleye Growth Rates

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AUTHORS: L. Zoe Almeida, Ohio State University; Matthew D. Faust, Ohio Department of Natural Resources, Division of Wildlife; Stuart A. Ludsin, Ohio State University; Elizabeth A. Marschall, Ohio State University

ABSTRACT: Growth rates of animals are often assumed to be a response to recent environmental conditions; however, there is increasing evidence from numerous organisms that growth in one year may also be reflective of environmental conditions experienced earlier in life. Therefore, large-scale stressors, such as eutrophication and climate change may affect individuals immediately and latently, which is rarely considered in the management of exploited populations. Herein, we examined the factors that may influence growth rates of Lake Erie walleye (Sander vitreus), a system exposed to eutrophication and climate change. We used data from annual fall gillnet surveys (1978-2015) to characterize median size-at-age of individual annual cohorts in response to changes in physical conditions (e.g., temperature) and the food web (e.g., prey availability) during early life (= age-2), which may have arisen due to eutrophication and climate change (i.e., warming and increased precipitation). We hypothesized that environmental conditions in the current year, growth rates during early-life (as a reflection of early-life environmental conditions), and growth rates in the previous year (as a reflection of recent growth) would affect age-specific annual growth rates. We performed preliminary linear mixed model analyses with the median size within cohorts at age-2 representing early life growth, median growth rate in the previous year, and annual average temperatures. Using a model selection approach, no combination of these factors was better able to predict growth rates than the null model. However, we still need to test for effects of age-0 growth on growth rates later in life and for other environmental effects on growth, including annual cumulative degree days, prey-fish availability, and walleye population size. Our analyses will assist Lake Erie fisheries managers by assessing the relative importance of early-life versus contemporary growth conditions on recent growth performance.

Tuesday January 29, 2019 10:20am - 10:40am EST