The Status of Fishes in the Missouri River, Nebraska: Lake Sturgeon \u3ci\u3e(Acipenser fulvescens)\u3c/i\u3e

Lake Sturgeon (Acipenser fulvescens) occurrences in the Missouri River along Nebraska’s eastern border are historically sporadic and rare. Presently, the wild Lake Sturgeon population in this river reach may be extirpated. A Recovery Program initiated by the Missouri Department of Conservation (MDC) has stocked almost 150,000 hatchery-reared Lake Sturgeon into the lower Missouri River at several sites in Missouri. As a result, the number of Lake Sturgeon collected has increased. Since monitoring began in 2003, no Lake Sturgeon have been collected above Gavins Point Dam while 40 fish were collected downstream of Gavins Point Dam. The majority of captures occurred in the lower channelized reach downstream of the confluence of the Platte and Missouri rivers. All fish collected are assumed to be progeny of MDC’s Recovery Program as either they were hatchery marked or their size (mean fork length = 764 mm, range = 602–997 mm) correlated with the expected growth rates. At present, their rarity warrants continued listing as a state threated species

The Status of Fishes in the Missouri River, Nebraska: Lake Sturgeon \u3ci\u3e(Acipenser fulvescens)\u3c/i\u3e

Lake Sturgeon (Acipenser fulvescens) occurrences in the Missouri River along Nebraska’s eastern border are historically sporadic and rare. Presently, the wild Lake Sturgeon population in this river reach may be extirpated. A Recovery Program initiated by the Missouri Department of Conservation (MDC) has stocked almost 150,000 hatchery-reared Lake Sturgeon into the lower Missouri River at several sites in Missouri. As a result, the number of Lake Sturgeon collected has increased. Since monitoring began in 2003, no Lake Sturgeon have been collected above Gavins Point Dam while 40 fish were collected downstream of Gavins Point Dam. The majority of captures occurred in the lower channelized reach downstream of the confluence of the Platte and Missouri rivers. All fish collected are assumed to be progeny of MDC’s Recovery Program as either they were hatchery marked or their size (mean fork length = 764 mm, range = 602–997 mm) correlated with the expected growth rates. At present, their rarity warrants continued listing as a state threated species

Prospective Validation of the Emergency Heart Failure Mortality Risk Grade for Acute Heart Failure: The ACUTE Study

Background: Improved risk stratification of acute heart failure in the emergency department may inform physicians\u27 decisions regarding patient admission or early discharge disposition. We aimed to validate the previously-derived Emergency Heart failure Mortality Risk Grade for 7-day (EHMRG7) and 30-day (EHMRG30-ST) mortality. Methods: We conducted a multicenter, prospective validation study of patients with acute heart failure at 9 hospitals. We surveyed physicians for their estimates of 7-day mortality risk, obtained for each patient before knowledge of the model predictions, and compared these with EHMRG7 for discrimination and net reclassification improvement. We also prospectively examined discrimination of the EHMRG30-ST model, which incorporates all components of EHMRG7 as well as the presence of ST-depression on the 12-lead ECG. Results: We recruited 1983 patients seeking emergency department care for acute heart failure. Mortality rates at 7 days in the 5 risk groups (very low, low, intermediate, high, and very high risk) were 0%, 0%, 0.6%, 1.9%, and 3.9%, respectively. At 30 days, the corresponding mortality rates were 0%, 1.9%, 3.9%, 5.9%, and 14.3%. Compared with physician-estimated risk of 7-day mortality (PER7; c-statistic, 0.71; 95% CI, 0.64-0.78) there was improved discrimination with EHMRG7 (c-statistic, 0.81; 95% CI, 0.75-0.87; P=0.022 versus PER7) and with EHMRG7 combined with physicians\u27 estimates (c-statistic, 0.82; 95% CI, 0.76-0.88; P=0.003 versus PER7). Model discrimination increased nonsignificantly by 0.014 (95% CI, -0.009-0.037) when physicians\u27 estimates combined with EHMRG7 were compared with EHMRG7 alone (P=0.242). The c-statistic for EHMRG30-ST alone was 0.77 (95% CI, 0.73-0.81) and 30-day model discrimination increased nonsignificantly by addition of physician-estimated risk to 0.78 (95% CI, 0.73-0.82; P=0.187). Net reclassification improvement with EHMRG7 was 0.763 (95% CI, 0.465-1.062) when assessed continuously and 0.820 (0.560-1.080) using risk categories compared with PER7. Conclusions: A clinical model allowing simultaneous prediction of mortality at both 7 and 30 days identified acute heart failure patients with a low risk of events. Compared with physicians\u27 estimates, our multivariable model was better able to predict 7-day mortality and may guide clinical decisions. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02634762

Assessing the Sustainability of Fish Communities in Glacial Lakes: Habitat Inventories and Relationships Between Lake Attributes and Fish Communities

Broad-scale aquatic habitat inventories have rarely been done in South Dakota waters. Even less has been done to understand the relationships between habitat variables and the fish communities in large lakes. The objectives of my research were to: 1) quantify the available aquatic habitats in 15 South Dakota large lakes, 2) investigate the use of Geographical Information System technology to create aquatic habitat layers, and 3) determine the relation of abiotic and biotic habitat characteristics to fish growth, size structure, body condition, and relative abundance in large South Dakota lakes. Aquatic habitat types were surveyed during the sununer months of 2000, 2001, and 2002 and found to be highly variable among large South Dakota lakes. Some of the lakes were recently expanded (due to above normal precipitation) and others have been relatively stable. The percent coverage of hard substrates (e.g., sand, gravel, or rock) ranged from 2.4 to 42. l. Submergent macrophyte coverage ranged from 0.5% to 31.1 %. The range of maximum depths was 2.8 m to 4.9 m. Shoreline development indices ranged from 1.4 to 4.5. There was between 15.9% and 66.7% cropland in Hydrologic Units associated with the study lakes. Total phosphorous levels ranged from 0.01 ppm to 0.46 ppm. Trophic State Indices based on chlorophyll-a ranged from 47.9 to 73.7. Secchi visibilities ranged between 0.5 m and 2.5 m. These characteristics result largely from the geology and land-use practices found in this region. The accuracies of Geographical Information System raster maps created from vector (point) data were assessed. Lake substrate data sets consisting of individual sample points were used to create interpolated substrate coverages. The accuracies of the coverages were analyzed based on sample point density. Analysis suggested that substrate sample point densities should be at least 1 point / 8 hectares to achieve an accuracy of 65% on interpolated maps of lakes having relatively homogenous substrates (e.g., Lake Madison). Lakes having substantial substrate heterogeneity (e.g., Pickerel Lake) should be sampled at a density of at least 1 point / 4 hectares to achieve the same accuracy. Correlation analysis suggested that a number of relationships existed between habitat and fish population characteristics. Submergent vegetation was negatively correlated with yellow perch Perca flavescens relative weight (Wr), yellow perch proportional stock density (PSD), and northern pike Esox lucius PSD. Lake basin ruggedness was negatively correlated with black crappie Pomoxis nigromaculatus PSD, northern pike Wr, and walleye Stizostedion vitreum Wr. Lake surface area was positively correlated with walleye Wr, walleye length at age 3, and yellow perch Wr. Nitrate levels were positively correlated with black bullhead Ameiurus me/as CPUE and northern pike CPUE, but negatively correlated with northern pike PSD and walleye Wr. Total phosphorous levels were positively correlated with black bullhead Wr and black crappie Wr. Chlorophyll-a levels were positively correlated with black crappie CPUE. Principal components analysis of the physical and biological habitat data produced three habitat component groupings. Maximum depth, basin slope, and two measures of basin complexity loaded highly on the Lake Basin a negative correlation between this component and northern pike Wr. Surface area, component. There was maximum fetch, and watershed area loaded highly on the External component. Yellow perch Wr was positively correlated to this component. For the Landscape component, submergent macrophyte coverage (positive), shoreline development index (positive), and the percent cropland in the Hydrologic Unit (negative) loaded highly. Black crappie PSD and black bullhead relative abundance were negatively correlated with the Landscape component. This study should serve as a foundation for future studies. The habitat sampling and GIS methodology should be duplicated on additional lakes for further comparisons. Habitat data can be used to monitor changes over time or implemented into fisheries management activities and research efforts. Correlations between habitat attributes and fish population characteristics may be considered when planning further studies, fish stockings, or habitat improvement projects

The Status of Fishes in the Missouri River, Nebraska: Blue Sucker Cycleptus elongatus

Blue Sucker Cycleptus elongatus are a large-bodied, benthic fish that are considered an indicator species for riverine health. A combination of historic commercial fishing and anthropogenic modifications to riverine habitat led to blue suckers being listed as a candidate species for the federal threatened or endangered species list in 1993. However, they were never designated a federally protected species. Locally, Blue Suckers are currently listed as a Nebraska Natural Legacy Project’s Tier 1 species but population changes and trends have not been quantified. Therefore, the objective of this paper was to evaluate the current population status of Blue Sucker in the Missouri River along Nebraska’s border. Over 12,000 Blue Suckers were sampled in Nebraska from 2003 to 2012 as part of a targeted effort to characterize the benthic fish community in the Missouri River. Blue Suckers were rarely sampled upstream of Gavins Point Dam. Sampling results from this reach indicate this remnant population is comprised of mostly large adults with very limited reproduction. Capture frequency increased downstream of Gavins Point Dam with adequate reproduction and recruitment to sustain the population in these reaches. Gill net catch consisted of 14% Blue Suckers in the unchannelized reach downstream of Gavins Point and 23% of the benthic fish community in the channelized reach upstream of the Platte River. Age-0 Blue Suckers were most frequently detected in 2011 during the extreme flooding conditions but were also detected in higher abundance in 2006 when the river remained in its channel. The overall population downstream of Gavins Point Dam appears stable or perhaps slightly increasing. Blue Suckers, as with most native fish populations, were negatively affected when the Missouri River was highly modified through dam construction and channelization. However, reproduction and recruitment is occurring and Blue Sucker are not as imperiled as Pallid Sturgeon Scaphirhynchus albus or the native Macrhybopsis species

The Status of Fishes in the Missouri River, Nebraska: Sauger (\u3ci\u3eSander canadensis\u3c/i\u3e)

Early fisheries investigation of the Missouri River fish community indicated that Sauger were common throughout Nebraska, including all major Missouri River tributaries. However due to many factors, their current range is restricted to the Missouri River and the lower reaches of a few tributaries. Hesse (1994) recommended listing Sauger as a state endangered species but this recommendation was never implemented. Therefore, the objective of this paper is to reevaluate the current population status of Sauger in the Missouri River along Nebraska’s border. Over 2,100 Sauger have been captured from the Missouri River along Nebraska’s eastern border since 2003. Sauger were most frequently captured in the riverine reach above Gavins Point Dam where they comprised 10% to 14% of the adult fish community captured. Sauger populations appear to be relatively stable throughout this reach over the past decade. Sauger were infrequently captured below Gavins Point Dam, representing less than two percent of the adult fish community. The Sauger population below Gavins Point Dam is highly variable making any long-term trends difficult to determine. The Sauger population reacted positively to the extreme flood conditions throughout the Missouri River in 2011, especially below Gavins Point Dam. As river management has not changed over the past half century, Sauger are just one of several native fish species experiencing greatly diminished population levels and rage contraction due to major river modifications

The Status of Fishes in the Missouri River, Nebraska: Shovelnose Sturgeon (\u3ci\u3eScaphirhynchus platorynchus\u3c/i\u3e)

The Shovelnose Sturgeon Scaphirhynchus platorynchus remains the most abundant riverine sturgeon species in North American despite the anthropogenic modifications that have occurred throughout their historic range; however, their populations have declined throughout Nebraska since the construction of Fort Randall and Gavins Point Dams. Therefore, the objective of this study was to present the current status of Shovelnose Sturgeon in the Missouri River along Nebraska’s border. Data was acquired from 2003 to 2012 from all reaches of the Missouri River along Nebraska’s eastern border. Catch rates of Shovelnose Sturgeon increased in a downstream trend and were highest in the reach below the Missouri and Platte River confluence. Based on gill net samples which collected the majority (39%) of Shovelnose Sturgeon, annual catch per unit efforts indicate a declining population above Gavins Point Dam and a stable population below in the open Missouri River. The length frequency distributions of Shovelnose Sturgeon collected were similar across all reaches with the exception of those captured between Fort Randall and the headwaters of Lewis and Clark Lake which were significantly larger than fish captured below the Platte River confluence. Although no age-0 Shovelnose Sturgeon were captured in the unchannelized reaches, age-0 abundance increased in a downstream trend throughout the channelized reaches. Preferred-sized fish (510-640 mm, N = 53,741) were the most common size category of Shovelnose Sturgeon captured throughout all reaches and across all years followed by quality-sized (380-510 mm, N = 12,089) and memorable-sized (640-810 mm, N = 4,569) fish. Our data concludes the overall population of Shovelnose Sturgeon above Gavins Point Dam appears to be slightly declining while the population in the open, lower river appears to be stable

The Status of Fishes in the Missouri River, Nebraska: Shoal Chub (\u3ci\u3eMacrhybopsis hyostoma\u3c/i\u3e), Sturgeon Chub (\u3ci\u3eM. gelida\u3c/i\u3e), Sicklefin Chub (\u3ci\u3eM. meeki\u3c/i\u3e), Silver Chub (\u3ci\u3eM. storeriana\u3c/i\u3e), Flathead Chub (\u3ci\u3ePlatygobio gracilis\u3c/i\u3e), Plains Minnow (\u3ci\u3eHybognathus placitus\u3c/i\u3e), Western Silvery Minnow (\u3ci\u3eH. argyritis\u3c/i\u3e), and Brassy Minnow (\u3ci\u3eH. hankinsoni\u3c/i\u3e)

Throughout the past century, the Missouri River has been highly modified which has negatively affected the native fish community. Previous research quantified the reduction of several native Cyprinidae species and made several recommendations to aid in recovery. However, these recommendations were not implemented. Therefore, the objective of this paper is to assess the current population trends of eight native cyprinid species and develop the current management objectives. Over 335,000 fish were collected from the Missouri River along Nebraska’s eastern border with mini-fyke nets and otter trawls from 2003 to 2012. Target Cyprinidae species consisted of less than five percent (n = 14,610) of the total catch with Silver Chubs (n = 11,804) comprising the majority (81%) of target species captured. State-wide all eight species were captured, although localized extirpations may have occurred. These native cyprinid species are extremely rare or extirpated upstream of Gavins Point Dam and populations continue to be limited downstream of Gavins Point Dam. Generally, relative abundance of these fish increased in the channelized reach, compared to the unchannelized reaches, but they no longer dominate the fish community. This shift in species composition and low relative abundance estimates continue to indicate imperilment of the Missouri River system

The Status of Fishes in the Missouri River, Nebraska: Pallid Sturgeon (\u3ci\u3eScaphirhynchus albus\u3c/i\u3e)

Anthropogenic alterations to the Missouri River have placed the Pallid Sturgeon (Scaphirhynchus albus) population in jeopardy and contributed to their listing as an endangered species. Pallid sturgeon were always less common than the sympatric Shovelnose Sturgeon (S. platorynchus); however, Pallid Sturgeon seemed to be more affected by river alterations as the river sturgeon ratio has become more skewed towards Shovelnose Sturgeon. Shortly after listing, population augmentation with hatchery produced Pallid Sturgeon began to supplement the diminishing wild population. Therefore, the objective of this study was to present the current population status of the Pallid Sturgeon in the Missouri River along Nebraska’s border. Moving upstream along Nebraska’s eastern border the population of wild Pallid Sturgeon declines and appears very minimal to non-existent upstream of Gavins Point Dam. The wild Pallid Sturgeon population below Gavins Point Dam appears unchanged over the past decade. Hatchery supplementation has stocked almost 12,000 hatchery-reared Pallid Sturgeon above Gavins Point Dam and over 135,000 below, these hatchery-reared fish are surviving and contributing to the overall population throughout all reaches as the capture frequency has increased annually. Currently, the Pallid Sturgeon population consists primarily of stock (66%) and quality- sized (22%) fish, most of which are of hatchery origin. Mean relative condition of quality and preferred-size Pallid Sturgeon varied spatially and temporally. As the Pallid Sturgeon population increases several population recruitment obstacles still exist. Until the bottleneck preventing natural recruitment is lessened, continued listing of the Pallid Sturgeon as an endangered species is critical to drive river management and restoration efforts which are likely to influence species recovery

The Status of Fishes in the Missouri River, Nebraska: Emerald Shiner (\u3ci\u3eNotropis atherinoides\u3c/i\u3e), Red Shiner (\u3ci\u3eCyprinella lutrensis\u3c/i\u3e), River Shiner (\u3ci\u3eN. blennius\u3c/i\u3e), Sand Shiner \u3ci\u3eN. stramineus\u3c/i\u3e), Spotfin Shiner (\u3ci\u3eC. spiloptera\u3c/i\u3e)

Despite major anthropogenic modification to the Missouri River system, relative abundance of five shiner species within Nebraska’s reach of the Missouri River has increased since the 1940’s. The combined abundance of five species: Red Shiner Cyprinella lutrensis, Spotfin Shiner C. spilopterus, Emerald Shiner Notropis atherinoides, River Shiner N. blennius, Sand Shiner N. stramineus, represented \u3e 50% of the small fish community in the Missouri River over the past ten years (2003-2012). More than 3,600 mini-fyke nets were deployed, resulting in over 158,600 shiners collected from the Missouri River along Nebraska’s eastern border between 2003 and 2012. Past literature has documented population declines of several native chub and minnow species; however, limited information exists about the magnitude of change in relative abundance and species composition amongst the fish community. A review of the population status for five shiner species and a discussion of population trends among four reaches along the borders of Nebraska are presented