No description available.

The measurement of total suspended solids (TSS) concentrations through water quality monitoring programs is laborious, costly, and time-intensive. Winter conditions further hinder water quality monitoring programs. The use of Acoustic Doppler Current Profilers (ADCPs) is currently being explored as a surrogate for estimating total suspended solids concentrations. TSS concentration and ADCP measurements were collected during the winter at the Lower Nelson River and the Red River such that ADCP backscatter data could be calibrated to TSS concentrations. Different calibration schemes were pursued, some involving flow parameters determined from ADCP data, in order to accurately model the data. Due to limited ranges in the data, further TSS concentration and ADCP measurements were taken during the open water period. Calibrations were achieved with varying degrees of accuracy, however the they failed to perform well beyond the ranges for which they were developed.

The measurement of total suspended solids (TSS) concentrations through water quality monitoring programs is laborious, costly, and time-intensive. Winter conditions further hinder water quality monitoring programs. The use of Acoustic Doppler Current Profilers (ADCPs) is currently being explored as a surrogate for estimating total suspended solids concentrations. TSS concentration and ADCP measurements were collected during the winter at the Lower Nelson River and the Red River such that ADCP backscatter data could be calibrated to TSS concentrations. Different calibration schemes were pursued, some involving flow parameters determined from ADCP data, in order to accurately model the data. Due to limited ranges in the data, further TSS concentration and ADCP measurements were taken during the open water period. Calibrations were achieved with varying degrees of accuracy, however the they failed to perform well beyond the ranges for which they were developed.

Master of Science / This project aims to develop computational tools for analyzing an underwater acoustic system designed to deter invasive fish species in the Mississippi River Basin. It leverages an established numerical framework (OpenFOAM) and deals with understanding how to model the system. The study prioritizes enhancing the accuracy of the methods developed and ways to improve its computational efficiency.

No description available.

This investigation examined the adequacy of the forage base to meet current demand of piscivores in Smith Mountain Lake, Virginia. Surplus production, or the maximum sustainable supply, of alewife (Alosa pseudoharengus) and gizzard shad (Dorosoma cepedianum) were determined using data on the biomass, growth, and mortality of each species. Mean hydroacoustic alewife biomass from 1993-1998 was 37 kg/ha and mean gizzard shad cove rotenone biomass from 1990-1997 was 112 kg/ha. Mean annual alewife surplus production was determined to be 73 kg/ha and mean annual gizzard shad surplus production totaled 146 kg/ha. Bioenergetics modeling and population density estimates were utilized to derive the annual food consumption (realized demand) of the two most popular sport fish in the system, striped bass (Morone saxatilis) and largemouth bass (Micropterus salmoides). The striped bass population consumed 46 kg/ha of alewife and 27 kg/ha of gizzard shad annually. Largemouth bass ate 9 kg/ha of alewife and 15 kg/ha of gizzard shad annually. Annual consumption by ancillary predators was estimated to be 13 kg/ha of alewife and 35 kg/ha of gizzard shad. Prey supply to predators is limited by morphology, behavior, and distribution. The cumulative effect on prey availability of these three factors, in addition to consumption by other predators, was quantified. For largemouth bass, available supply of alewife and gizzard shad exceeded demand by 20% and 53% respectively. For striped bass, available supply of gizzard shad surpassed demand by 30% but available alewife supply was only 4% greater than demand. Annual demand of all predators was 94% of total available clupeid supply. Striped bass stockings were increased by 50% in 1998 and will remain at this level in the near future. A predator-prey simulation model of alewife and striped bass populations was developed to explore the consequences of increased predator demand. This model incorporated dependencies between alewife abundance and mortality and the mortality, abundance, and growth of striped bass. Model output showed that a 50% stocking increase has a near-zero probability of increasing the mean annual number of legal and citation striped bass in Smith Mountain Lake. / Ph. D.

Seismic waterguns produce acoustic energy that has the potential to affect aquatic organisms. This study examined the effects of exposure to a 1,966.4 cm³ watergun array (two units) on the abundance, behavior, and spatial distribution of Asian carp (Hypophthalmichthys spp.) and native fish species (i.e., bigmouth buffalo, Ictiobus cyprinellus; black buffalo, Ictiobus niger; channel catfish, Ictalurus punctatus; flathead catfish, Pylodictis olivaris; freshwater drum, Aplodinotus grunniens; gizzard shad, Dorosoma cepedianum; smallmouth buffalo, Ictiobus bubalus). Waterguns were deployed, approximately centered and perpendicular to the shoreline, in a channel that connects the Illinois River to a set of backwater gravel pits. To evaluate the effect of waterguns, six mobile side-looking split-beam hydroacoustic surveys were conducted at fixed times over a period of 12 days, during and between replicated watergun firing periods. Acoustic data collected over a five day period before placement of the waterguns were used as a control. Proximity to the waterguns of the first detected Asian carp while the watergun array was operational (52.95 ± 7.41 m, mean ± SE) was not different relative to when turned off (36.53 ± 6.08). In contrast, the closest detected native fish were farther from the waterguns while firing (32.38 ± 3.32 m) compared to when they were off (15.04 ± 1.6 m). The waterguns did not affect the abundance of acoustically detected Asian carp within the survey area, but the abundance of native fish was reduced during the firing treatment (115.82 ± 10.19) compared to both the control (203.46 ± 12.12) and off treatment (175.84 ± 12.16). The cumulative abundance of Asian carp relative to distance from the waterguns, examined at 50 m intervals up to 480 m bi-directionally away from the waterguns, was sporadically different (i.e., reduced abundance while the waterguns were firing) between treatments (i.e., at the 250, 300, 350, and 480 m intervals). In contrast, there was a significantly lower cumulative abundance of native fish during the firing treatment at every distance interval tested. The spatial distributions, relative to distance away from the waterguns, of both fish groups were affected by the firing of the waterguns. During active operation of the waterguns, there were proportionally less targets of both fish groups detected within a 50 m radius. While firing, there were proportionally more native fish farther than 400 m away on either side of the waterguns, and a larger proportion of Asian carp farther than 400 m from the waterguns on the northern side of the channel (i.e., closer to the Illinois River main channel). Asian carp and native fish were both more likely to be detected closer to the HMS pits when the waterguns were turned off. The watergun array did not influence the directional movement of detected Asian carp. In contrast, native fish were less likely to swim towards the IL River while the waterguns were firing versus not firing. The size distributions of both Asian carp and native fish species that remained in the survey area did not change across watergun treatments. It is concluded that the seismic watergun array examined in this study had a greater impact on native fish species than on Asian carp. Due to the lowered abundance, but not complete suppression of fish, it is suggested that the watergun array (as tested) is not suitable as a barrier for areas where absolute exclusion of fish is desired. The results from the spatial distribution analyses suggest the tested watergun array could be more suitable as a herding tool to facilitate removals of large fish aggregations. Caution should be taken to the extrapolation to other fish species and to fish exposed to seismic waterguns in different environments (i.e., deeper water, reduced shoreline interaction) or exposure to a larger array of waterguns.

Ichtyofauna with emphasis on fish fry community was studied in cascade reservoir complex of the Vltava River. Fish spatial distribution and species composition was observed along longitudinal axis of Kamýk, Slapy, Štěchovice and Vrané reservoirs using hydroacoustic, trawling and beach seining.

Annotation Long-term fixed-location hydroacoustic study with uplooking transducer was performed during 2005 in Římov reservoir, Czech Republic. It dealt mainly with fish behaviour in the open water of reservoir, especially with sinusoidal swimming behaviour. The dependence of pelagic fish behaviour on environmental conditions was also studied.

Informing monitoring and surveillance efforts for invasive species is crucial for effective management to minimize negative ecological, economic, and social impacts. Management responses to the invasion of silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis)—collectively termed bigheaded carps—in the upper Illinois waterway involve removal efforts to maintain low abundance near the invasion front and surveillance to detect any spread farther upriver. However, the efficiency and effectiveness of these efforts may be limited by the low abundance and patchy distributions of bigheaded carps near the invasion front, as well as the spatial scope of the gears used to sample them. My thesis applied mobile hydroacoustic sampling to understand the factors influencing the distributions of silver carp near the invasion front in the upper Illinois waterway, and factors influencing the observability and detectability of fishes with this gear. These results will be useful to inform removal and surveillance efforts in the upper Illinois waterway and reduce the risk of further upstream invasion into the Great Lakes. To assess factors influencing abundance, bi-monthly (March – October) mobile hydroacoustic sampling was conducted from 2017-2018 and paired with continuous environmental variable data collection in the Dresden Island and Marseilles pools, the upper two invaded pools of the Illinois waterway. Environmental variables collected were water temperature, dissolved oxygen, total dissolved solids, turbidity, chlorophyll-a concentration, blue-green algae concentration, and depth. Logistic and multiple regressions were performed within pool during each sampling period to describe factors associated with silver carp presence, and factors associated with their densities in areas where they were present. Silver carp densities fluctuated across space and time, suggesting environmental variables influenced distributions. Depth was the most consistent predictor of silver carp presence and density, with shallower depths associated with higher abundance. Specifically, in summer months, areas in large backwater habitats with lower temperature, higher dissolved oxygen, and higher chlorophyll-a concentration tended to hold more silver carp. These results suggest removal efforts should be focused on shallower depths within sites, and should target areas in backwaters with lower water temperature, higher dissolved oxygen, and higher chlorophyll-a concentrations during summer months. To inform bigheaded carp surveillance efforts upstream of the invasion front, the influence of factors of vessel speed, wind speed, and beam compensation on the observability (the proportion of the true abundance of fish that fall within the acoustic beam) and detectability (the proportion of observable fish that are detected) of fishes in large rivers with mobile horizontal hydroacoustic sampling was also evaluated. To accomplish this, 23 sets of paired trawl floats (buoys) were deployed in a 2.1 km stretch of the Dresden Island Pool, and four sets of replicate hydroacoustic surveys were conducted past them at three vessel speeds. Mean wind speed during each survey was obtained, and proportion of buoys observed and detected were quantified under two different maximum beam compensation values (6 dB and 12 dB). Results revealed significant interactions between vessel speed and wind speed, with observability increasing with wind speed at slow and fast vessel speeds, but decreasing at intermediate vessel speeds. Detectability decreased with greater wind speed across all vessel speeds, with more pronounced effects at slower vessel speeds. Significant positive effects of beam compensation occurred for both observability and detectability. These results suggest, to improve detection of bigheaded carps, sampling should be focused on calm days under moderate vessel speeds when analyzing with standard beam compensation values. Broadening beam compensation was shown to increase observability and detectability, but needs further investigation. Ultimately, these studies provide valuable information to assist management efforts to control bigheaded carps near the invasion front in the upper Illinois waterway, and detect any individuals that may spread farther upriver towards the Great Lakes.