This thesis has examined the influence of the environment on aspects of the acute stress response in juvenile and pro-larval Acipenser fulvescens.The acute stress response was examined in grouped and isolated juveniles. Catecholamines significantly increased in both treatments one minute post-stress and plasma glucose was significantly higher in isolated as compared to grouped fish one minute post-stress. In the second series of experiments fertilized eggs of A. fulvescens were raised at 9, 12 & 15°C. Chromaffin-like cells were studied using light and electron microscopy techniques. Development of renal tissue was also examined in these treatment groups. Two populations of chromaffin-like cells were identified, one in close association with the proximal tubule of the kidney, and the other in close association with the neural tube. Results suggest this latter population were immature pheochromoblast like-cells. Development of renal tissue followed a predictable pattern that was most rapid in the 15°C treatment.

This thesis has examined the influence of the environment on aspects of the acute stress response in juvenile and pro-larval Acipenser fulvescens.The acute stress response was examined in grouped and isolated juveniles. Catecholamines significantly increased in both treatments one minute post-stress and plasma glucose was significantly higher in isolated as compared to grouped fish one minute post-stress. In the second series of experiments fertilized eggs of A. fulvescens were raised at 9, 12 & 15°C. Chromaffin-like cells were studied using light and electron microscopy techniques. Development of renal tissue was also examined in these treatment groups. Two populations of chromaffin-like cells were identified, one in close association with the proximal tubule of the kidney, and the other in close association with the neural tube. Results suggest this latter population were immature pheochromoblast like-cells. Development of renal tissue followed a predictable pattern that was most rapid in the 15°C treatment.

Thesis (M.S.)--Michigan State University. Dept. of Fisheries and Wildlife, 2008. / Title from PDF t.p. (viewed on Aug. 7, 2009) Includes bibliographical references (p. 62-64). Also issued in print.

Thesis (Ph. D.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 7, 2007) Includes bibliographical references.

Due to habitat degradation and overharvest (Colombo et al. 2007) sturgeon populations are declining throughout their global distribution (Pikitch et al. 2005). In North America, five sturgeon species are listed as endangered or threatened due to overharvest and habitat degradation. One species of direct concern is the pallid sturgeon (Scaphirhynchus albus ) (Boreman 1997). The morphologically similar shovelnose sturgeon (S. platorynchus) is not listed as endangered but has become a cause for concern due to poor reproductive success and declining recruitment of their offspring to the adult population, likely a result of lack of proper spawning habitat and early life foraging opportunities (Wildhaber et al. 2007). Despite listing the pallid sturgeon as endangered and increasing concern about population decline, little information is available about the foraging ecology of age–0 Scaphirhynchus sturgeon. To ensure these sturgeon populations persist in the Middle Mississippi River, a better understanding of sturgeon foraging success during early life is imperative. I quantified age–0 Scaphirhynchus sturgeon (total length (TL) range: 14–200 mm; small < 50 mm TL, large 50–200 mm TL) diets during 2004–2008 to determine whether foraging behavior changed as a function of stage height, water temperature, water velocity, size class of sturgeon, and macrohabitat. I also examined whether energy density (cal/g) and selection of prey varied across size class and macrohabitat. Age–0 Scaphirhynchus sturgeon were collected from the Middle Mississippi River during spring (March, April, May), summer (June, July, August), and fall (September, October, November). Each prey item in diets was identified to family and measured to calculate dry weight. Ephemeroptera, Diptera pupae, and Chironomidae were the dominant taxa that were consumed across all years and seasons. Large sturgeon had a broader diet, consuming more non–dominant taxa. Abiotic factors differed across macrohabitats and thus influenced foraging behavior. Sturgeon occupying the island upstream tip (IUT) macrohabitat had the largest mean mass in diet and those at the island downstream tip (IDT) had the lowest mean mass in diet. Conversely, energy density of sturgeon was highest at IDT and lowest at IUT. Small sturgeon avoided macroinvertebrates that were outside the dominant prey taxa whereas large sturgeon selected for Chironomidae across all macrohabitats. Diets of age–0 Scaphirhynchus sturgeon vary as a function of size and are influenced by interacting of abiotic and biotic factors at each macrohabitat. As age–0 Scaphirhynchus sturgeon grow, their diet broadens. Diet of young sturgeon interacts with energy condition in counterintuitive ways that requires more study. Because foraging success differs among habitats and is likely linked to recruitment, habitat quality and quantity in the Middle Mississippi River is likely critical for sturgeon population density and growth.

No description available.

Substrate composition plays a critical role in determining the spawning success of Atlantic sturgeon. A benthic analysis of the tidal freshwater portion of the James River, Virginia, was performed to locate and protect remaining sturgeon spawning habitat within the James River system. I modeled structural habitat, substrate distribution, and river bathymetry from Richmond, Virginia to the Appomattox River confluence. A classification model was developed to describe the dominant substrate type (mud/silt, sand, gravel, bedrock) using side scan sonar data collected from August 2011-Febuary 2012. River depth, bottom imagery, substrate density (hardness), and ground truth substrate samples were interpolated into a GIS model to spatially describe and quantify essential sturgeon spawning habitat. Finally, I attempted a change analysis of historical substrate composition throughout the study area. Gravel, cobble, and bedrock, swept clean of silt or mud, was deemed a hard bottom substrate suitable for spawning success. Mud and silt dominated the vast majority of river substrate, representing approximately 67 % of river bottom surveyed. Sand comprised 17 % of river bottom, gravel represented 11 % and bedrock represented 5 %. Sixteen percent of the reach was hard bottom habitat consisting of a bed substrate dominated by gravel, cobble, or bedrock. Regions of hard bottom habitat found at depths ≥ 10 m were selected to model essential sturgeon spawning habitat. The river bottom within the reach contained approximately 8 % essential spawning habitat. The majority of hard bottom habitat was located in major bends of the river where scouring occurs. The historical comparison of available hard bottom habitat identified a 28 % loss of hard bottom since 1853. The greatest losses in hard bottom occurred in the upper portions of the study area (55 % loss in hard bottom habitat). Hard bottom habitat lost in the lower portion of the study area was partially offset by the creation of new hard bottom habitat within the narrow channel cuts bypassing Jones Neck and Turkey Island. Historical comparison of the Hatcher Island, Turkey Island, and Jones Neck oxbows identified heavy siltation and reduced depths likely due to anthropogenic alterations in the meander bends linked to shipping channel creation. The altered flow regime has resulted in increased sedimentation and has drastically reduced available hard bottom substrate within the natural channel of Jones Neck and Turkey Island. The increased availability of hard bottom habitat within the confines of the shipping channel has indicated that the alteration of the river bottom, through flow modification and dredging practices, may have replaced a portion of lost historical spawning habitat. Fisheries managers could use the data from the substrate analysis to better understand and protect essential areas necessary for Atlantic sturgeon spawning success.

Research developing artificial propagation, husbandry, and nutrition of sturgeon species has developed greatly since the collapse of the Caspian Sea fisheries in the 1980s. Sturgeon species are commercially prized for their unfertilized roe which is marketed as the delicacy, caviar. Sturgeon production units commonly utilize commercial salmonid feeds, which contain large proportions of fish meal (FM) and fish oil (FO). Concerns regarding economics and sustainability have put pressure on aquafeed manufactures to efficiently utilize FM and FO, and to incorporate alternative protein sources, such as soybean meal (SBM). Therefore, the present studies estimated the optimal protein:energy ratio of juvenile Pallid Sturgeon Scaphirhynchus albus and evaluated the effects of increasing SBM composition on growth, feed efficiency, body and liver composition, and intestinal morphology of juvenile Shovelnose Sturgeon Scaphirhynchus platorhynchus, two species of Scaphirhynchus sturgeon of regional commercial importance. Protein:energy ratios were investigated using casein and dextrose based, semi-purified diets. Results indicated that Scaphirhynchus sturgeon are able to perform similarly across a wide range of protein:energy ratios (79 - 147 mg protein kcal-1), so long as adequate dietary energy (3,800 kcal kg-1 gross energy) is provided and essential amino acids are not limiting. Soybean meal was evaluated utilizing practical, isocaloric, isolipidic, isoenergetic test diets, designed to replace FM with increasing SBM. Juvenile Scaphirhynchus sturgeon were found to perform similarly on diets with up to 50% of FM replaced with SBM (336 g kg-1 diet). Evaluation of liver composition revealed that juvenile Shovelnose Sturgeon store less glycogen and crude lipid than other fish species, although no dietary differences were observed. Histological evaluation of the distal intestine revealed indications of SBM induced enteritis, though no statistical differences in measures were detected between treatments. This research is the first to describe optimal dietary formulation for the culture of Scaphirhynchus sturgeon.

No description available.

Rivers are inherently dynamic environments with fluctuations in water quality, hydrology, connectivity and geomorphology. Though geomorphology has long been recognized as an important driver defining biological, ecological, and physical habitat characteristics of rivers, a readily applied classification tool that links such characteristics has been lacking. The Geomorphic Response Unit (GRU) method provides a novel approach to identifying large scale patterns in geomorphic character that provide a link between the hydrological regime and different habitat types to which species respond. Specifically, I investigated whether Geomorphic Types and GRUs are related to the distribution and abundance of different fish species, reflecting unique physical habitat characteristics of individual GRUs. The thesis chapters are manuscript based. The second chapter identifies relationships between specific Geomorphic Types, identified using the Geomorphic Response Unit (GRU) methodology, and Lake Sturgeon overwintering locations in the South Saskatchewan and Saskatchewan Rivers. Habitat selection ratios suggest that Lake Sturgeon in the Upper South Saskatchewan River significantly selected for one of seven possible Types for overwintering. Logistic regression results found both Type 0 and Type 4 predicted significantly higher Sturgeon presence than all other Types (P = < 2e-16 for both). The third chapter examines relationships between GRUs and abundance of both mature and immature Carmine Shiner in the Birch River, Manitoba. Differences in the median mature Carmine Shiner CPUEs among the GRUs are not statistically different (Kruskal-Wallis test H =1.723; df = 3, p value = 0.632), though interesting qualitative relationships were identified which may inform further studies. The fourth chapter investigates whether GRUs derived using a large scale network approach are linked to the abundance of specific fish species in the Assiniboine River, Manitoba. A Kruskal-Wallis test identified significant differences in CPUE among GRUs for 10 of 14 tested species. Post-hoc pairwise multiple comparisons using Dunn’s Method with Bonferroni p-value correction for multiple paired tests isolated the GRUs that were different from one another. Overall, my findings suggest that Geomorphic Response Units (GRU) are an effective means of identifying patterns in geomorphic structure within Prairie Rivers at both reach and segment scales. Further, I identified links between both Geomorphic Types and GRUs and patterns in abundance of various fish species covering a wide range of life history traits. These findings suggest that GRUs have potential as a valuable fisheries habitat management tool, increasing efficiency of monitoring efforts through quantification of habitat availability, connectivity, and complexity in Prairie River systems.