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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: LAKES & RESERVOIRS) Otolith Microchemistry as a Tool to Understand Contributions of Stocked Channel Catfish in Reservoir Populations

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AUTHORS: Cory Becher, The Ohio State University, Aquatic Ecology Laboratory, EEOB; Stephen M. Tyszko, Ohio Department of Natural Resources-Division of Wildlife; Dr. John Olesik, The Ohio State University, Trace Elements Research Laboratory; Dr. Stuart A Ludsin, The Ohio State University, Aquatic Ecology Laboratory, EEOB

ABSTRACT: Stocking is a key management tool used to establish or enhance fisheries in reservoir ecosystems. Quantifying the contribution that stocked individuals make to the fishable population should be an essential component of any stocking program. However, such post-stocking assessment is oftentimes neglected, likely owing to difficulties associated with using conventional (i.e., artificial) tags to discern stocked individuals from wild-produced ones. To help the Ohio Division of Wildlife (DOW) better assess its Channel Catfish (Ictalurus punctatus) reservoir stocking program, we have been evaluating the use of otolith microchemistry—quantified using laser-ablation plasma-mass spectrometry—as a natural tag to discriminate between stocked and wild-produced individuals. Herein, we first present results from predictive quadratic discriminate function (QDF) models that were developed for three reservoirs, which we used to differentiate wild-produced individuals from hatchery-reared individuals. These models were built using known signatures from the hatchery and reservoirs. We used core and edge chemistry of hatchery-reared broodstock and juveniles, as well as the recent edge chemistry of individuals captured in the three reservoirs. Afterwards, we present findings from our predictive analyses, which used the QDF models to classify reservoir individuals unknown core signatures as either stocked (hatchery origin) or wild-produced. Our preliminary findings indicate that otolith microchemistry can be used as a tool to identify the natal origin of wild-caught fish in our study reservoirs, with stocked fish comprising less than half of the population at large in each reservoir. We ultimately discuss the value of this approach for helping management agencies such as the Ohio DOW assess the effectiveness of their channel catfish stocking programs.

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