Browsing by Author "Dr. Joseph E. Hightower, Committee Chair"

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Characterizing American Shad Spawning Habitat in the Upper Roanoke River Basin, Virginia
(2005-04-28) Read, Alesia Noelle; Dr. Joseph E. Hightower, Committee Chair; Dr. Kenneth H. Pollock, Committee Member; Dr. Thomas J. Kwak, Committee Member
Populations of American shad (Alosa sapidissima) have declined from historical levels due to overfishing, decreased water quality and habitat losses including those due to dam construction. One approach for restoring these populations is to identify suitable habitat upstream of dams that could be restored through dam removal or by providing fish passage. The goal of this research is to identify and characterize potential spawning habitat for American shad in the upper Roanoke River basin of Virginia, above Kerr Reservoir. Five mainstem rivers that are upstream of the Roanoke Rapids, Gaston, and Kerr dams (Big Otter, Staunton, Banister, Dan, Hyco) were the focus of this research. Roanoke Rapids Dam is the first obstruction to American shad spawning migration in the Roanoke River basin, and just completed the FERC (Federal Energy Regulatory Commission) relicensing process in 2004. One of the provisions of the new license is to evaluate a trap and transport program for spawning American shad. Characterizing the habitat above the dam, in terms of suitability, is an important step in predicting the benefits of fish passage. A detailed physical habitat assessment, including monthly water quality monitoring, indicated that the Banister and Hyco rivers consistently had lower dissolved oxygen concentrations and may provide lower quality habitat for American shad compared to the other rivers. However, according to the current published Habitat Suitability Index (HSI) model, which incorporates surface water temperature and current velocity as criteria for suitable habitat, the five rivers appear to contain suitable habitat with HSI values ranging from 0.83 to 1.00 during May. I constructed a modified HSI model with surface water temperature and current velocity, as well as dissolved oxygen, pH and a component for substrate composition. The modified model suggested that the Big Otter and Staunton rivers would provide the highest quality spawning habitat for American shad because of the presence of gravel, cobble and bedrock substrates. Larger substrates have been suggested to be preferred over smaller substrates by spawning adult American shad in the Neuse River, NC. Egg incubation experiments were conducted during the American shad spawning season, from mid-April to the end of May 2004, throughout the basin. Hatching success from incubation experiments was relatively high (69-94 percent). No significant differences (p<0.05) among incubation sites were found in terms of hatching success, which suggests that water quality throughout the basin is suitable for egg development. The combination of field data and habitat suitability modeling used to predict habitat quality was an efficient approach for assessing habitat and could be used by planners and managers working to restore American shad populations in other river systems. Results from the physical habitat assessment, the habitat suitability modeling and the egg incubation results suggest that a trap and transport program should be successful for spawning American shad in the Roanoke basin.
Estimating Run Size of Anadromous Fishes in the Roanoke River, North Carolina, using Hydroacoustics
(2006-08-14) Mitchell, Warren Anderson; Dr. Joseph E. Hightower, Committee Chair; Dr. Jeffrey A. Buckel, Committee Member; Dr. Kenneth H. Pollock, Committee Member
The annual arrival of American shad Alosa sapidissima, striped bass Morone saxatilis and hickory shad Alosa mediocris is ecologically and economically important in the rivers of North Carolina. Both species support commercial and recreational fisheries, and both are the focus of management efforts by state and federal agencies. Reliable information about population levels is essential for effective management. The goal of this study was to estimate the number of adult spawners returning to the Roanoke River. During April-May 2004 and March-May 2005, a stationary 430 kHz hydroacoustic system was deployed on the river bottom in a side-aspect orientation. Tracks of upstream-migrating fish were discernable from ambient noise. The number of fish migrating upstream was slightly lower during 00:00-08:00 compared to the other two 8-hr periods of the day. A majority of fish tracks were within 2 m of the river bottom in both years (89%), and were more associated with ranges near shore. Drift gill netting and boat electrofishing appear to provide an adequate measure of the seasonal presence and absence of target species, though electrofishing provides better samples size. These traditional fisheries methods confirmed the expected seasonal pulses of hickory shad, followed by striped bass, during both years. Counts of upstream fish tracks were low during periods between these pulses. Daytime electrofishing catch rates for 2005 were correlated with daily counts of upstream fish tracks. American shad occurred sporadically at low abundance throughout both years. It was the main target species in this study but made up less than 2% of the catch in both years. A majority of fish captured by gill netting (85%) were within two meters of the river bottom. Analysis methods were standardized in 2005 based on lessons learned in 2004. The 2004 species-specific estimates were 9,046 American shad and 126,176 striped bass. The default estimates (and SEs) for 2005, assuming a uniform cross-channel density of upstream migrants, were 7,054 (450) American shad and 118,778 (4,799) striped bass. Using alternative assumptions about detectability of fish tracks and the cross-channel distribution of upstream migrants, estimates ranged between 5,422 (346) and 13,604 (887) American shad and 94,529 (3,807) and 534,750 striped bass. This first large-scale assessment of the Roanoke River American shad population is difficult to compare with surveys of relative abundance. Estimates of striped bass abundance appear low when compared to traditional stock assessment results. The largest uncertainties regarding the hydroacoustic monitoring is the cross-channel distribution of upstream migrants. For American shad, our study points to the difficulty in assessing the abundance of a target species that is rare in biological samples. Using hydroacoustics to estimate run sizes appears to be feasible, but improvements to the study design are needed. Further validation will improve both accuracy and precision of estimates, and allow fishery managers to use hydroacoustic results with confidence in making management decisions.
Spawning Activity and Migratory Characteristics of American Shad and Striped Bass in the Cape Fear River, NC
(2009-08-05) Smith, Joseph Alan; Dr. Kevin Gross, Committee Member; Dr. Thomas J. Kwak, Committee Member; Dr. Joseph E. Hightower, Committee Chair
SMITH, JOSEPH ALAN. Spawning Activity and Migratory Characteristics of American Shad and Striped Bass in the Cape Fear River, NC. (Under the direction of Joseph E. Hightower) Anadromous fish populations within the Cape Fear River, NC have experienced declines since the late 1800s. Three low-head lock and dam structures contributed to this decline by limiting access to upstream habitat. I used egg sampling and sonic telemetry to characterize patterns of migration and spawning activity for American shad and striped bass. Plankton samples were taken below each lock and dam, and at two locations farther upstream. Distribution and stage of development of American shad eggs, as well as observed spawning activity, suggest that most American shad spawning took place below the lowermost lock and dam (river km (rkm) 97). Egg density decreased by an estimated 90% for each successive dam moving upstream. In 2007, 20 American shad and 20 striped bass were captured and transported to a release location upstream of the three locks and dams, where they were tagged with sonic transmitters and released. Sixty percent of American shad in 2007 moved 1 to 33 rkm upstream of the release site, at an average migration rate of 2.30 rkm/hr. All 2007 striped bass moved downstream upon release. However, two striped bass made secondary upstream migrations of 52 and 134 rkm, through two and three dams respectively, and at an average rate of 2.58 rkm/hr. In 2008, 20 American shad and 20 striped bass were captured, tagged with sonic transmitters, and released at their capture locations (all but two striped bass downstream of the first lock and dam). Sixty-five percent of American shad and 77% of striped bass made upstream movements past the lowermost lock and dam in 2008, with average migration speeds of 3.2 rkm/hr for American shad and 3.0 rkm/hr for striped bass. Furthermore, 35% of American shad and 25% of striped bass that made upstream movements were able to migrate upstream of the uppermost lock and dam (rkm 186). Combined results suggest that Lock and Dam #1 had the highest egg collections and a tie for the predicted proportion of the American shad run (35%, tied with the upper river), and Lock and Dam #3 had the highest egg collections and highest predicted proportion of the striped bass run. The locking program established for upstream fish passage provides some access to historical spawning habitat, although spawning of American shad is concentrated in areas below the dams. Further improvements in fish passage should benefit both species.
Status of shortnose sturgeon, Acipenser brevirostrum, in the Neuse River, North Carolina
(2003-07-17) Oakley, Nathaniel Corey; Dr. Joseph E. Hightower, Committee Chair; Dr. Richard L. Noble, Committee Member; Dr. Kenneth H. Pollock, Committee Member
The purpose of the research was to determine if shortnose sturgeon, Acipenser brevirostrum, occur within the Neuse River, North Carolina. Shortnose sturgeon historically occurred in most major Atlantic Coast rivers from Saint Johns River, New Brunswick, Canada to St. Johns River, Florida. Anecdotal evidence suggests that a population of shortnose sturgeon once occurred in the Neuse River, North Carolina, but their current status was unknown. In compliance with the National Marine Fisheries Service shortnose sturgeon sampling protocol, a two-year intensive gillnet survey was conducted in order to determine the population status of shortnose sturgeon within the Neuse River. Habitat surveys showed that the lower Neuse River, where shortnose sturgeon would be expected to occur during summer, was severely hypoxic in June - September of 2001 - 2002. No shortnose sturgeon were observed during the two-year survey (> 200 h of netting effort) although four juvenile Atlantic sturgeon were encountered. These two species occupy similar habitats in other river systems. A juvenile Atlantic sturgeon tagged with a transmitter moved upstream of the unsuitable habitat and remained in a restricted area until late fall, when water quality improved due to increased flows and lower temperatures. The probability of detection for varying population sizes of shortnose sturgeon was calculated in order to determine if adequate sampling had been completed to conclude an absence of shortnose sturgeon in the Neuse River. The detection analysis stated that a population size of 50 or more individuals should be detected in 200 h of netting effort. Therefore, based on our sampling efforts, we hypothesize that shortnose sturgeon are extirpated from the Neuse River. We believe that poor water quality is a key factor in the extirpation of shortnose sturgeon in the Neuse River. Population recovery may be impossible until habitat quality can be improved. Finally, we observed that shortnose sturgeon have a disjunct distribution with an absence spanning from Chesapeake Bay to Pamlico Sound tributaries. Logistic regression models based on river characteristics were developed to help predict presence of shortnose sturgeon within a river system. River characteristics included in the models: total length, estimated watershed area above the fall line, and distance to the first dam. These characteristics described size of the river system, available spawning habitat, and blockage to spawning migration. Current models suggested that large river systems with sufficient spawning habitat and no blockages to migration are more likely to contain a population of shortnose sturgeon. The models predict that the Neuse River should contain a population of shortnose sturgeon; therefore, leading to further evidence that poor water quality within the Neuse River may be the key factor to the recovery of the species.