The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on December 22, 2009). Thesis advisor: J. Mark Morgan, Ph.D. Includes bibliographical references.

Many fishes are planktivorous during early life and switch to piscivory or consume larger food items as ontogeny progresses. In contrast, paddlefish begin life as active feeders selecting for larger organisms and then switch to planktivory as they grow. Few studies have quantified these changes in early life foraging. I identified distinct early life foraging behaviors and prey preferences of age-0 paddlefish and how these change with habitat and paddlefish size. Gut contents of 189 age-0 wild paddlefish were used to determine which prey are most preferred and whether habitat variables and paddlefish size influence diet composition. I also performed an experiment to identify differences in foraging behavior and prey preference between age-0 and age-1 paddlefish. Dominant prey, based on percent by number and percent occurrence, of wild age-0 paddlefish ranging from 10 to 116 mm TL was trichoptera larvae (28.5%N, 67.7%O) and hemiptera (18.3%N, 51.3%O). Prey size increased with size of age-0 paddlefish. However, the highest ratio of zooplankton to invertebrates in the gut occurred in a 60 mm paddlefish. The size range of fish in this study was likely too narrow to confirm presence of an ontogenetic diet shift. Habitat had no effect on diet. My experimental study revealed that if provided a mixture of organisms, age-0 paddlefish will primarily consume macroinvertebrates while age-1 paddlefish will mainly filter zooplankton, but occasionally consume larger organisms. Features of river channels (e.g., woody snags, gravel beds in the photic zone) that contribute to the diverse diet paddlefish require in early life may ultimately increase survival and recruitment.

Paddlefish (Polyodon spathula) is a commercially and recreationally important species, with a native range that extends over 22 US states. This is a large, long-lived, highly mobile riverine species that has been negatively impacted by habitat fragmentation, historic overharvest, and hatchery supplementation. Dams are the primary cause of habitat fragmentation, blocking migration routes, flooding spawning grounds, and isolating populations. A common management action to mitigate the impacts of habitat fragmentation and maintain harvestable populations is hatchery propagation and stocking. Reduction in stock size, isolation of populations, and stocking can all negatively impact the genetic integrity of Paddlefish. I evaluated the impacts of isolation and hatchery supplementation on the effective population size (Ne) of Paddlefish as well as the range-wide genetic structure of Paddlefish.

Bio-structures owe their remarkable mechanical properties to their hierarchical geometrical arrangement as well as heterogeneous material properties. This dissertation presents an integrated, interdisciplinary approach that employs computational mechanics combined with flow network analysis to gain fundamental insights into the failure mechanisms of high performance, light-weight, structured composites by examining the stress flow patterns formed in the nascent stages of loading for the rostrum of the paddlefish. The data required for the flow network analysis was generated from the finite element analysis of the rostrum. The flow network was weighted based on the parameter of interest, which is stress in the current study. The changing kinematics of the structural system was provided as input to the algorithm that computes the minimum-cut of the flow network. The proposed approach was verified using two classical problems – three- and four-point bending of a simply-supported concrete beam. The current study also addresses the methodology used to prepare data in an appropriate format for a seamless transition from finite element binary database files to the abstract mathematical domain needed for the network flow analysis. A robust, platform-independent procedure was developed that efficiently handles the large datasets produced by the finite element simulations. Results from computational mechanics using Abaqus and complex network analysis are presented. The complex network strategy successfully identified failure mechanisms in the bio-structure by identifying strain localization in regions of tension, and buckling/crushing in regions of compression. The transdisciplinary strategy used in this study identified the failure mechanisms early, when the material was still in the linearly elastic regime, thereby tremendously reducing the computational time and cost as compared to running a finite element analysis to failure. This work also developed five proof-of-concept, bio-inspired models with varying lattice complexity based on the rostrum. Performance of these bio-inspired models was analyzed with respect to the stress and deformation. Numerical experiments were carried out on one of the bio-inspired model to demonstrate the application of newly developed similitude laws for blast loading. This research has laid the groundwork for an efficient design-test-build cycle for rapid prototyping of novel bio-inspired structures by using flow network analysis, finite element analysis, and similitude laws.

Water resources for Bluff Lake in Mississippi are managed to achieve objectives related to waterfowl, waterbirds, fish, anglers, and Paddlefish (Polyodon spathula). Annually, the reservoir undergoes a nine-stage seasonal drawdown and re-inundation to improve waterfowl habitat. In addition, weekly discharges are released from the water control structure to encourage Paddlefish spawning and migration each spring. However, additional discharges throughout the year may provide additional passage opportunities. In this study, multiple discharge states were evaluated to identify optimal water releases during each drawdown period given reservoir objectives. First, I developed a hydrodynamic model to predict daily changes in lake volume. Second, I defined functional relationships between water surface elevation and management objectives. A structured decision-making framework was then applied to determine the optimum additional discharge strategy. This approach allowed trade-offs between management objectives to be evaluated and optimal water releases to be identified for this multiuse reservoir.

Paddlefish are long-lived large river fish which are declining in many areas of their range due to habitat modifications and overfishing. A framework for management of paddlefish in Mississippi is proposed and a case study of its application to the paddlefish population of the Tennessee-Tombigbee Waterway (TTW) is presented. The framework includes four phases: (I) distribution and stock assessment; (II) determination of limiting factors; (III) design and implementation of management actions; and (IV) review and monitoring. Phase I of management in the TTW consisted of gill-net surveys in four impoundments. Paddlefish abundance was estimated at 1,581 to 8,851 in Demopolis Lake, Alabama. In Gainesville Lake, Alabama, CPUE was 16.8 times less than Demopolis Lake. No paddlefish were caught in Aliceville Lake, Mississippi/Alabama, or Columbus Lake, Mississippi. Demopolis Lake paddlefish grew faster than more northern populations, but slower than more southern populations (Lt = 971.8 [1 − e−0.2844 (t+0.6962)]) and had a high annual mortality rate (A = 0.406) comparable to other southern populations. Potential limiting factors related to spawning in Demopolis Lake and stocking programs in Columbus Lake were investigated pursuant to Phase II. Paddlefish eggs were collected in the Noxubee River and a unique flowing bendway habitat in Demopolis Lake during early April when discharge was ¡Ý2.74 m above 50% exceedance. Flow timing and magnitude in the Noxubee River was related to paddlefish year-class strength (linear regression P = 0.089; R2 = 0.830). Radio-tagged paddlefish exhibited seasonal site fidelity and 4 of 10 translocated fish returned to their area of initial capture.,Columbus Lake provides food resources and physiochemical characteristics adequate for paddlefish survival, but depth and zooplankton density are more favorable in Demopolis Lake. Emigration of stocked juvenile paddlefish was low in Columbus Lake habitats; survival (percent after one month ¡À SE) was 5 ¡À 5 in backwaters and 28 ¡À 9 in the mainstem after one month. Phase III recommendations include further investigation of early life history requirements and protection of bendway and tributary habitat in Demopolis Lake. The annual stocking of 4,000 juvenile paddlefish in the mainstem of Columbus Lake and up to 1 million larval paddlefish in a tributary is recommended.

Thesis (Ph.D.)--Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.

The purpose of the experiment was to verify of the influence of enriched artemia salina on the growth and survival of American paddlefish larvae (Polyodon spathula) in operating conditions. The control group was compared with group which was fed by artemia enriched by preparation Red pepper. Control group was fed by nonenriched artemia. This preparation contained increased amount of vitamins A, C, D3 and E, but especially HUFA, mainly DHA (docosahexaenoic acid). The larvae were fed by artemia only one week and then they were fed gradually by dry mixture for larvae. After a five-day co-feeding they were fed only by dry mixture for larvae. The whole experiment was 4 weeks. In the group which was fed by enriched artemia was statistically higher average weight (247.80 +- 40.36 mg) and average length of body (31.19 +- 1.03 mm) versus the control group. Average weight of control group was 140.76 +- 23.06 mg and average lenght of body was 25,27 +- 0.73 mm. Also average survival of the two groups was statistically different at the end of the experiment. The group which was fed by enriched artemia demonstrated an average survival 15.43 +- 2.90 %, while the control group only 2.20 +- 1.92 %. Only rate of cannibalism was not influenced by enrichment of artemia. But these results, mainly survival was negatively influenced by Ichthyophthirius multifiliis, which was detected on the skin after five days of the experiment. Another parameter was average amount of individual fatty acids in the body of larvae from both groups. In the group which was fed with enriched artemia was found statistically higher level of LA (linoleic acid), LNA (-linolenic acid) and DHA. On the other hand, higher levels of ARA (arachidonic acid), EPA (eicosapentaenoic acid) and DPA (docosapentaenoic acid) was found in control group.