Date of Award
Master of Science
Channel Catfish are broadly distributed in the U.S. and are important commercially and recreationally in many rivers, lakes, reservoirs, and streams. Since they are a popular sportfish, many state-owned lakes are stocked with a variety of sizes to enhance population sizes and provide angling opportunities. The goals of this study were to determine the contributions of stocked fish, determine the fish size at stocking, and to assess the contribution of yearling and catchable sizes to the stocked percentage. Fish samples were obtained from three hatcheries and six lakes within different ecoregions across Arkansas to assess whether chemical signatures were different among locations. Sectioned pectoral spines were analyzed for Sr:Ca and Ba:Ca using laser ablation-ICPMS to determine whether location-specific Sr:Ca and Ba:Ca signatures were reflected in pectoral spine samples, and to assess the accuracy with which fish could be assigned to their collection location using spine Sr:Ca and Ba:Ca. Fin spine core Sr:Ca and Ba:Ca data were also used to identify stocked fish and determine size at stocking for hatchery-origin fish sampled from each of the six lakes. Spine microchemistry represents a non-lethal approach to identify stocked catfish and infer size at stocking, which will better inform allocation of hatchery-produced fish. Differences in pectoral spine Sr:Ca edge signatures among locations were detected, which were primarily driven by differences in geology among ecoregions. Assignment accuracy of fish to collection location using Random Forest Modeling was 88% or greater for all but one of the study lakes. This allowed for application of the random forest model on pectoral spine core Sr:Ca and Ba:Ca to assign individuals sampled from the lakes as hatchery or wild origin. Among all the Channel Catfish sampled from the six lakes, 45% were identified as hatchery origin and 46% of those were stocked as catchable size fish. Contributions of stocked fish varied among study lakes from 0% to 100%. This was the first study to demonstrate that pectoral spine microchemistry can be used for assessing both stocking contribution and inferring fish size at stocking. Overall, this study will aid in the allocation of hatchery-reared catfish by management biologists, and could lead to more projects focused on exploring stocking contribution by microchemistry, such as assessment of how habitat enhancement may influence the contribution of natural reproduction to catfish populations.
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