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AUTHORS: Stephen M. Tyszko, Matt A. Hangsleben, Richard D. Zweifel, Jeremy J. Pritt, Joseph D. Conroy - Ohio Division of Wildlife
ABSTRACT: Standardizing fisheries assessment methods to minimize variation in catchability, maximize catch, and use appropriate sample sizes allows collection of rigorous datasets which in turn facilitate hypothesis testing and statistical inference. Although there is a growing awareness of the importance of standardization, there are few examples where standard methods have been evaluated to confirm that the data they collect meet management needs. We used mark-recapture methods to estimate Largemouth Bass Micropterus salmoides electrofishing catchability using Ohio Division of Wildlife standard methods and confirmed that those standard methods minimized catchability variation and maximized catch. Using a resampling analysis, we confirmed that electrofishing CPUE statistically differed between reservoirs that had a real difference in Largemouth Bass density, thereby validating CPUE determined via standard Ohio methods as an index of density. The resampling analysis also estimated statistical power and false positive rate as number of sample sites changed. We are now using this approach to develop and validate a standard hoop net survey designed to sample Channel Catfish Ictalurus punctatus in Ohio reservoirs. We fished tandem, baited hoop nets during a mark-recapture experiment from May - July, 2016 to estimate catchability and identify the temporal period with minimal variation and maximum catch. Additional effort in 2017-2018 at reservoirs that likely differ in Channel Catfish density will allow tests for differences in CPUE and assessments of how power and false positive rate changes with sample size. Here we describe a general, logical approach to validating standard methods, provide an example where the approach validated aspects of an existing standard survey design, show how the approach can be used to develop a new standard assessment, and demonstrate application of the approach to fundamentally different gear types.
Monday February 6, 2017 4:00pm - 4:20pm CST
Garrat