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.

Quality of populations of brown trout (Salmo trutta m. fario) influence of occurence of freshwater pearl mussel (Margaritifera margaritifera) in river in the Czech Republic. Freshwater pearl mussel is a critically endangered species of animals. It does not have a very specific requirements only on environment but mainly on a specific host for holding glochidia (larval stage of pearl mussel). Thus fish management and migratory permeability of flow for support of existing populations is very important. Basic and essential precondition to support populations of freshwater pearl mussels is the presence of viable populations of brown trout, which represents the only suitable host glochidia. There are five locations with the biggest occurrence of pearl mussel in the Czech Republic - river basins the Blanice, the Teplá Vltava, the Malše, the Rokytnice and the Jankovský potok. The management of these flows is under local organizations of Czech Fishing Union, the National Park and Protected Landscape Area of the Šumava, the Secondary School of Fisheries in Vodňany and Faculty of Fisheries and Protection of Waters. The present management was found in the questionnaire for representatives of farming organizations. According to the answers in the questionnaire, the change of plans of restocking was recommended in the river basins of the Teplá Vltava and the Jankovský potok. There is the cooperation with the Germany was recommended in the river basin of the Rokytnice. The restoration of fish nursery is suitable in the river basin of the Malše. There is the first-rate population of brown trout in the river basin of Blanice, thus the continue in the present fish management for next support of this population in sequence on the populations of freshwater pearl mussel was recommended

Fishpond ecosystems provide many other services besides fish production. One of them is the retention of nutrients and thus ability to change the quality of the through flowing water, thereby ability to influence the overall quality of surface waters. In the case of the fishpond Svět in Třeboň it is also recreation, as the pond is an integral part of the tourism of the town. Water quality in the fishpond and its retention capacity of phosphorus is connected with the fish management and the inflow of nutrients from the catchment basis, especially within a cascade of ponds and densely populated or agricultural regions. This thesis evaluates seasonal (2013, 2015) and long term (2007-2015) trend of water quality of pond Svět in Třeboň in relation to fish management. Furthermore, mass balance was calculated for 2015 and estimated for 2013. The years 2015 and 2013 (the first years of production cycle) varied considerably in amount of annual rainfall. The year 2015 was extremely dry and 2013 very aqueous. Different hydrological conditions caused different seasonal courses in hydrochemistry parameters and its concentrations. The water quality of fishpond Svět is in the most of parameters better in comparison with other production fishponds in the Třeboň region and also the intensity of fish management is...

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