VTechWorks Repository :: Browsing by Author "Nielsen, Larry A."

Browsing by Author "Nielsen, Larry A."

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An analysis of the contamination by and effects of highway- generated heavy metals on roadside stream ecosystems
Mudre, John M. (Virginia Polytechnic Institute and State University, 1985)
This study examined the consequences of the opening and operation of a new highway north of Richmond, Virginia with respect to contamination of the aquatic environment with heavy metals (Zn, Cd, and Pb), and the effects of these metals on the biota of roadside streams. Sixteen sites located on six small, soft-water streams that were crossed by the highway, encompassing six reference sites located upstream of the highway, six sites located directly at the highway, and four sites located downstream of the highway, were sampled over a two and a half year period, allowing both spatial and temporal analyses. Traffic densities on the highway averaged about 12,000 vehicles per day (vpd). Significant increases in the metals concentrations of sediment, benthic invertebrates, fish whole-bodies, and fish tissues (liver, kidney, and bone) were noted over the course of the study, although the increase varied in magnitude, and were not always consistent. Sediment metals concentrations followed a dynamic plateau. Fish whole-body concentrations of Cd and Pb increased steadily over the course of the study. Spot-sampling for the same parameters along another nearby, more heavily traveled highway (50,000 vpd) indicated that increases in metals concentrations in the different ecosystem components at the study streams would have been greater had there been more traffic. A number of biotic parameters were investigated to determine whether metals contamination was affecting the biological integrity of the study sites. These were: benthic macroinvertebrate diversity and density; the percentage of the aquatic insect community that was composed of chironomids; and fish community diversity, density, and biomass. Only benthos density, the percent chironomids, and fish species diversity showed changes that could be related to metals contamination. Indications from spot sampling along the more heavily traveled highway were that if more contamination had been experienced, more biotic parameters would have been disturbed, and to a larger extent. Fish community structure analyses using the Pinkham-Pearson coefficient of similarity indicated that fish community structure became increasingly altered at highway sites, and to a lesser degree downstream sites, over the study period.
Approaches to management effectiveness in state fish and wildlife agencies
McMullin, Steve L. (Virginia Tech, 1993-04-01)
Agency directors, program administrators and planners as well as U. S. Fish and Wildlife Service regional federal aid supervisors provided input that defined 22 factors considered most important in determining management effectiveness of state fish and wildlife agencies. I grouped the factors into the following six categories: public support and awareness, conflict resolution, politics, planning and funding, agency management and personnel. State agency directors, commissioners and legislators ranked the factors. In cooperation with the U. S. Fish and Wildlife Service and Organization of Wildlife Planners, I conducted case studies of nine state fish and wildlife agencies widely recognized by their peers as being particularly effective relative to the identified factors. Questionnaires and interviews with 845 agency members and constituents revealed effective fish and wildlife agencies had much in common with the excellent companies described by Peters and Waterman (1982) in In Search of Excellence. Effective agencies were proactive in dealing with issues and frequently among the nation's leading agencies in dealing with issues of national scope. Effective agencies used a variety of techniques to understand public desires and involve the public in making important decisions. Effective agencies grant their employees much freedom to make decisions and try new ideas without fear of punishment for making mistakes. They are committed to the personal development of employees. Effective agencies are good planners, with well defined missions and goals. Personal missions of employees are highly congruent with agency missions, resulting ina missionary-like zeal for their work. Effective agencies have a strong biological basis for their decisions and maintain credibility by balancing biological factors with public opinion. Effective agencies have stable political environments and experienced, enlightened resource management professionals as their leaders. Leaders emphasize participative decision making and teamwork. Finally, effective agencies have strong public support and are effective in mobilizing that support when important policy decisions are made. Many specific examples that illustrate the characteristics of effective agencies are discussed.
Assessing potential navigation impacts to the Kanawha river ecosystem: a modeling approach
Hershfeld, Donald Christopher (Virginia Tech, 1987-12-05)
An extensive study of the biota of the Kanawha River was integrated to examine the trophic basis of fish production and predict potential impacts of increased tow traffic at two sites in the Winfield Pool. Total standing stock and production of adult fish were estimated as 242 kg/ha and 188 kg/ha/yr, respectively. Sixtyâ one species were categorized into six trophic groups. Trophic generalists (omnivores and herbivore/detritivores) consumed a variety of foods including considerable detritus. These groups accounted for 73 to 83% of total ichthyomass and 81% of total adult production. Total fish consumption at the more riverine upper site was partitioned into 35% l detritus, 28% invertebrates, 20% plant matter, 12% other fish, and 5% crayfish. At the lower, more lentic site the diet consisted of 34% detritus, 25% plant matter, 21% other fish, 17% invertebrates, and 3% crayfish. The overall basis of production relies upon imports of allochthonous materials.
Bald eagle distribution, abundance, roost use and response to human activity on the northern Chesapeake Bay, Maryland
Buehler, David A. (Virginia Tech, 1990-01-11)
I studied bald eagle (Haliaeetus leucocephalus) distribution, abundance, roost use and response to human activity on the northern Chesapeake Bay from 1984-89. The eagle population consisted of Chesapeake breeding eagles, Chesapeake nonbreeding eagles, northern-origin eagles and southern-origin eagles; changes in overall eagle distribution and abundance reflected the net changes in these 4 groups. Breeding territories on the northern Chesapeake increased from 12 to 28 from 1984 to 1988. Breeding eagles were resident all year, always ~7 km from the nest. Chesapeake nonbreeding eagles moved throughout most of the bay, but rarely left it (~5% of the radio-tagged eagles were off the bay during any month). Northern eagles migrated into the bay in late fall (x = 21 December! n = 7! range = 61 days) and departed in early spring (x = 27 March, n = 14, range = 43 days). Southern eagles arrived on the northern bay throughout April-August (x = 6 June, n = 11, range = 94 days) and departed from June - October (x = 3 September, n = 22, range = 119 days). Northern Chesapeake eagle abundance peaked twice annually; in winter (261 eagles, December 1987), driven by the presence of northern eagles, and in summer (604 eagles, August 1988), driven by the presence of southern birds. Of 1,117 radio-tagged eagle locations, only 55 (4.90/0) occurred in human-developed habitat, which composed 27.7% of 1,442 km2 of potential eagle habitat on the northern Chesapeake Bay (P < 0.001). During 36 aerial shoreline surveys, eagles were observed on only 111 of 700 (15.9%) 250-m shoreline segments that had development within 100 m, whereas eagles were observed on 312 of 859 (36.30/0) segments when development was absent (P < 0.001). On average, eagles were observed on 1.0 segment/survey that had coincident pedestrian use within 500 m, compared to 3.6 segments/survey expected if eagles and pedestrians were distributed along the shoreline independently (n = 34 surveys, P < 0.001).
The case for environmental moderation (or why people who live in recycled bottles shouldn't throw stones)
Nielsen, Larry A. (University of California Press, 1981)
I am an environmentalist. I turn off the water while I brush my teeth, and I only buy beer in returnable bottles. I started a paper-recycling system in my department at the university. And, as soon as I can afford it, I'm going to trade my roomy, comfortable station wagon for a car that gets conscience-soothing gas mileage. Perhaps, though, I'm not an environmentalist at all. Perhaps I'm just overly conscientious. I use my turn signals when no one is around to notice. I always flush in public toilets, and I contribute a dime every time I get coffee from the departmental pot (well, almost every time).
Compatibility and complementarity of alewife (Alosa pseudoharengus) and gizzard shad (Dorosoma cepedianum) as forage fish in Smith Mountain Lake, Virginia
Tisa, Mark Steven (Virginia Polytechnic Institute and State University, 1988)
The attributes of alewife and gizzard shad as coexistent forage fishes for striped bass (Morone saxatilis), walleye (Stizostedion vitreum vitreum) and largemouth bass (Micropterus salmoides) were evaluated in Smith Mountain Lake, an 8,337 ha hydroelectric impoundment in south-central Virginia. Alewife and gizzard shad larvae exhibited strong spatial segregation which minimized the potential for direct trophic competition and increased feeding opportunities for piscivores. Gizzard shad spawning peaked in June while alewife spawning peaked in July. Daily growth rate of age-0 gizzard shad was 37% greater than for age-0 alewives. Later spawning and slower growth enhanced temporal and morphological availability of alewives to piscivores and reduced the potential for exploitative competition between the clupeids. Distributional analysis indicated that gizzard shad were primarily uplake and littoral while alewives were mostly downlake and pelagic. Alewives co-occurred with striped bass and walleye during the growing season and were crucial in providing forage for these piscivores. Largemouth bass shared a common distribution with gizzard shad and were more trophically dependent than other piscivores on them. Prey supply and predator demand were one year out of phase; gizzard shad and alewife production peaked in the first year of life while their predators' cohort production peaked in the second year. Cohort production analysis indicated that over their lifespan, striped bass prey demand (per 1000 fish) would exceed that of walleye and largemouth bass by 17% and 166%, respectively. Lifespan cohort production patterns and ingestibility limitations on prey assured that most predation pressure in Smith Mountain Lake came from piscivores ages 0-2 and was constrained to alewives ages 0 and 1 and young-of-the-year gizzard shad. Prediction of patterns of consumption of alewife and gizzard shad by piscivores was derived from analyses of morphological and distributional availabilities; these agreed closely with actual diets for most predator-prey location, season and age combinations. The alewife appears to be both compatible with, and complementary to, the gizzard shad as a forage species in Smith Mountain Lake. Suitability of alewives for introductions into other reservoirs will vary with the morphometry and management objectives for those waters.
Controlled cultivation techniques for the recovery of threatened fishes in Virginia
Stoeckel, Joseph Norman (Virginia Tech, 1993)
The goal of this research was to develop captive propagation methods for the Federally threatened spotfin chub, Cyprinella monacha, and yellowfin madtom, Noturus flavipinnis, by using closely related, but unthreatened species, to evaluate potential techniques. The surrogate species used were the whitetail shiner, Cyprinella galactura, and the margined madtom, Noturus insignis. I investigated methods to promote gonadal maturation, induce spawning, and rear larvae of these fishes. Captive whitetail shiners developed mature gonads under a variety of temperature and photoperiod conditions. Spawning condition was maintained for over two years when they were held at constant warm temperature (≈ 24 C) and long photoperiod (16 h light). Whitetail shiners did not readily spawn in aquaria, but were induced to spawn by hormonal injection with human chorionic gonadotropin (hCG) and carp pituitary extract (CPE) at mean dosages of 1688 I.U./kg and 20 mg/kg, respectively, or with luteinizing hormone releasing hormone analogue (LHRHa) and domperidone at mean dosages of 363 µg/kg and 36 mg/kg, respectively. Most females spawned within 30 h of the first injection. Stripped ova were effectively wet-spawned, and larvae hatched in 8 d at 25 C. I obtained a mean hatch rate of 55 %, but lack of swimbladder inflation resulted in very poor survival of several batches of eggs. Larvae began feeding within 2 d of hatching, and survival rates of 50 to 90 % after 16 d were obtained when larvae were fed twice daily on a diet of brine shrimp nauplii at a rate of ≈ 10/L/d, and a commercially prepared larval fish diet at a rate of ≈ 14 mg/L/d. Changing photoperiod, but not temperature, was required to induce oocyte maturation in most captive female margined madtoms. Sperm production in mature male madtoms was enigmatic; motile sperm were observed only once. Plasma testosterone concentrations in males peaked just prior to the spawning season at 6.5 ng/mL, but levels were not correlated with male gonadosomatic values. Plasma 17β-estradiol levels in females peaked just prior to the spawning season at 15 ng/mL, and were correlated with gonadosomatic values. Captive margined madtoms did not tank spawn unless they were hormonally injected with hCG and CPE at mean dosages of 5256 I.U./kg and 58 mg/kg, respectively, or with LHRHa and domperidone at mean dosages of 554 µg/kg and 55 mg/kg, respectively. Most females ovulated within 78 h of the first injection. Inclusion of more than one breeding pair per tank inhibited tank spawning. Embryos did not develop in 55 % of tank-spawned ova, or from any strip-spawned ova. Parents consumed spawned egg masses if they remained with the nest. Hatch rates > 65 % were obtained by suspending egg masses in a large-mesh basket over turbulent aeration at 28 to 30 C. Larvae hatched in 7 d at 28 C. Survival rates > 50 % after 15 d were obtained when larvae were fed salmon starter twice daily at a rate of 20 mg/L/d, and tanks were thoroughly cleaned daily.
Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survival
Odom, Michael Cooper (Virginia Tech, 1987-09-15)
Distributions of larval fishes in the Winfield Pool, Kanawha River, West Virginia, were determined by sampling two sites with bongo and push nets. Cyprinids, clupeids, and Aplodinotus grunniens dominated collections. Main channel densities were a fraction of the densities along the shoreline, indicating the importance of the shoreline as a nursery. Diel trends in abundance were evident for several taxa, but were likely caused by diel changes in gear avoidance and distribution of larvae. Vertical trends in abundance were apparent for several taxa at the deeper and more lentic sampling site (lower pool). Aplodinotus grunniens were generally more abundant near the bottom, especially during daylight. Cyprinids were more abundant near the bottom in mid-June, but displayed no vertical trends on other sampling dates. Clupeids were more abundant at middepth or surface during daylight, while equally dispersed or near the bottom at night. Vertical trends were not evident at the shallower and more lotic site (upper pool) except for Aplodinotus grunniens, which displayed the same preference for the bottom, as at the lower site.
The effects of acid and water hardness on bluegill embryo-larvae determined by laboratory and on-site toxicity tests
Moynan, Kathleen M. (Virginia Tech, 1989-11-15)
The sensitivity of bluegill (Lepomis macrochirus) to low pH in soft (12 or 18 mg/L CaCO₃) and hard (165 or 197 mg/L CaCO₃) water was compared in five day laboratory toxiclty tests. Embryo-larval bluegill were exposed to pH levels ranging from 3.8 to 7.0 in soft water and from 3.8 to 8.0 in hard water. An on-site toxicity test, using lake water (3.4 mg/L CaCO₃) adjusted to pH levels ranging from 3.5 to 7.3, was conducted to compare laboratory and field results. At low pH, hatching was reduced, the hatching period prolonged, and the incidence of partial hatching increased. Increased water hardness mitigated acid toxiclty, enhanced larval survival, and promoted hatchability. Hatching rates were decreased over those of the controls by 76 percent in soft water and by 23 percent in hard water at pH 4.0, and hatching was negligible at pH 3.8. The length of the hatching period was prolonged by 24 to 48 hours at pH levels ≤4.6. Partial hatching averaged 43 percent in pH 4.4. Increasing acidity resulted in increased embryo-Iarval mortality, averaging >62 percent at pH levels ≤4.6; mortality was 100 percent at pH levels <4.4 in soft water and 3.8 in hard water. Bluegill larvae were more sensitive than eggs. The embryo-larval LC50's were pH 4.67 in soft water and pH 4.06 in hard water; LC1's were pH 5.66 in soft water and 5.04 in hard water. In the on-site field experiment, approximately 50 percent mortality occurred at pH 4.6 which was nearly identical to the LC5O of pH 4.67 in laboratory (soft water). Growth of larvae was not affected by low pH. As acid levels increased, yolk-sac volumes decreased, physical deformities (fin, eye, and spinal abnormalities) increased and behavioral abnormalities were evident. Yolk-sac volume was decreased at pH levels <5.5 in soft water and <5.1 in hard water, perhaps reflecting higher energy expenditures by larvae held at sublethal pH levels. Spinal curvature and fin erosion of larvae were apparent at pH levels <5.25 in soft water. Larvae were lethargic and swimming ability was impaired at pH levels ≤5.5 in soft water and ≤5.1 in hard water. Exposure of embryo-larval bluegill to low pH levels (<5.7) in soft water may compromise their ability to survive, forage efficiently, and escape predation under natural conditions.
The effects of coal mining on sedimentation and fish assemblages in the Powell River, Virginia
Temple, Alan J. (Virginia Tech, 1997)
An ecological study was undertaken on the Powell River system in Virginia from 1988 - 1990 to evaluate the effects of land uses on hydrology, water quality, sedimentation (particle size < 2 mm), and fish assemblages and to derive ecological indicators for monitoring. The hydrologic (disturbance) regime of the sixth order reach was Classified. Although surface coal mining appears to have reduced flow variance, the changes were not sufficient to alter the hydrologic classification. Tributaries draining coal-mined lands had elevated specific conductivity, iron, manganese, sulphate, and turbidity relative to tributaries in unmined watersheds or in the sixth order mainstem (p ≤ 0.05). The fifth order reach, which had a greater proportion of watershed area surface-mined, exhibited higher specific conductivity, iron, sulphate, turbidity, and total solids than the sixth order (p ≤ 0.05). Despite the upstream-to-downstream, lower-to-higher water quality gradient, there was no compelling evidence from the use of state water quality standards and a nine-variable water quality index that water quality differentially affected fish assemblages. The primary physical habitat gradient in the lower river was sedimentation. Upstream, embeddedness increased in shallow-water habitats (p ≤ 0.001) and sediment depth increased in pools (p ≤ 0.001). Stepwise multiple regression analysis indicated that variation in sediment level was explained primarily by the proportion of the watershed surface-mined (R² = 0.75). Index of Biotic Integrity scores for fish assemblages were not correlated with sedimentation in shallow-water or in pool habitats (p > 0.066). Functional metrics, as opposed to taxonomic metrics, however, varied with sedimentation (p ≤ 0.002). In shallow-water habitats, omnivore relative abundance increased and specialized insectivore abundance decreased in higher sedimented sites. Top carnivore abundance decreased in pools with higher sedimentation levels. Abundance of lithophilous benthic spawners, postulated as the most sediment-sensitive reproductive guild, was not consistently correlated with sedimentation. Nine fish species were classified as sediment-intolerant and eight were classified as sediment-tolerant. The sediment-intolerant group was composed mostly of benthic insectivores. Habitat analyses indicated that sediment-intolerant species, as a category, utilized microhabitats with low sedimentation levels relative to the sediment-tolerant species group (p ≤ 0.0001). Species not classified as either sediment-intolerant or sediment-tolerant utilized microhabitats intermediate in sedimentation level (p ≤ 0.0001).
Effects of liming on plankton and young-of-the-year bluegill growth in Flat Top Lake, West Virginia
Coahran, David Alan (Virginia Tech, 1990-01-15)
The responses at three trophic levels (phytoplankton, zooplankton, young-of-the-year bluegill) were compared between a limed and unlimed arm in a moderately fertile, circumneutral reservoir that was sensitive to acidification, but had not yet shown signs of damage. The east arm (25.5 ha) of Flat Top Lake was treated with 28.8 dry metric tonnes of calcite using slurry box technology between July 13-20, 1987. The design was confounded because calcite dissolution products diffused into the unlimed (west) arm after the treatment which made total alkalinity similar between the arms within 1 month. Phytoplankton gross productivity and chlorophyll a was similar between the arms for the pre- and post-treatment samples as well as for the period after the treatment when total alkalinity was relatively higher in the limed arm. Zooplankton biomass was higher in the unlimed than limed arm in the pre-treatment samples but was similar between the arms in the post-treatments samples; however, the changes in zooplankton biomass after treatment in the limed arm could not be attributed to the treatment. Phytoplankton community composition for the common netplankton and nannoplankton was similar between the limed and unlimed arms for the combined pre- and post-treatment samples: however, Gemellicystis spp., Gloeocystis spp., and Dinobryon spp. showed an order of magnitude higher density in the limed relative to the unlimed arm on the initial post-treatment sample. This difference, as well as the observed post-treatment differences in zooplankton community composition between the two arms could not be attributed to the treatment because there were minimal impacts on nutrient levels (e.g., CO2, total phosphorus) and zooplankton-phytoplankton interactions. Lake transparency was significantly deeper in the limed arm relative to the unlimed arm for the post-treatment samples; however, a corresponding lower dissolved organic carbon concentration was not measured in the limed arm. Young-of-the-year bluegill (e.g., primarily those 15-20 d old) showed significantly higher growth rates in the unlimed arm during the period when total alkalinity was higher in the limed arm, apparently due to a higher density of suitable pelagic zooplankton in the unlimed arm during this period. In conclusion, no significant positive or negative responses to the treatment were detected because of trophic level interactions. The high pre-treatment pH (7.07), small change in post-treatment pH, low dissolution percentage (8-10%), the inability of the sediment dose to neutralize the acidic sediments and induce phosphorus release, and phosphorus rather than carbon dioxide limited primary productivity were the main factors why no significant post-treatment biological responses were detected.
Factors related to angler compliance in a black bass fishery, James River, Virginia
Kokel, Ron W. (Virginia Tech, 1991-01-05)
An on-site interview and mail survey questionnaire of anglers on the James River, Virginia, was conducted to compare the characteristics of anglers, estimate angler compliance and illegal harvest, and determine the factors related to angler compliance with a black bass slot length limit regulation of 280 to 356-mm (11 - 14 in) and a daily creel limit of five bass. Boat and bank anglers differed significantly in yearly tackle expenditures, travel distances, knowledge of existing regulations, and species preference. Angler compliance with the slot limit averaged nearly 85% for the entire river, while angler compliance with the creel limit was over 99%. The total illegal harvest of black bass averaged approximately 10% of the total bass harvested. Comparisons between known complying anglers and known non-complying anglers showed differences in daily bait expenditures and yearly tackle expenditures. Non-complying anglers had a yearly tackle expense that was one-half that of complying anglers, and a daily bait expense that was more than twice that of complying anglers. All other characteristics were similar. Comparisons between anglers who knew the regulations and those who did not showed differences in species preference and yearly tackle expenditures. For fishery managers, understanding the factors related to an angler's probability of complying will be an important criteria when establishing or changing fishing regulations. By understanding those factors that cannot be manipulated by managers and serve only as predictors of compliance (i. e., angling methods), and those factors that can be modified (i. e., regulation knowledge), managers should better comprehend angler behavior.
Feeding ecology of age-o smallmouth bass in the New River, West Virginia
Easton, Robert S. (Virginia Tech, 1992-03-05)
The purpose of this study was to determine the food habits of age-O smallmouth bass (Micropterus dolomieu Lac~p~de) in the New River and to examine spatial, temporal, and size-related differences in foraging success. Understanding factors that regulate foraging success of age-O smallmouth bass may provide further insight into factors regulating yearclass strength in smallmouth bass populations. Larval and juvenile smallmouth bass (8.5-85 mm Total Length; TL) were collected from two sites in the New River, West Virginia in the late spring and early summer of 1990. Stomach analysis revealed that the first foods of smallmouth bass (TL - 9 mm) were primarily Chironomidae and Copepoda. Aquatic insects, primarily Ephemeroptera, became more abundant in the stomachs as TL increased. A shift in the proportions and types of prey consumed occurred at approximately 15 mm TL and was attributed to increased mouth width and fin development.
A fisheries and wildlife resource indicator system for use in natural resource management
Knuth, Barbara Ann (Virginia Polytechnic Institute and State University, 1986)
The development of a fisheries and wildlife indicator system is described. The system is intended to serve as a planning and policymaking aid for state fisheries and wildlife agencies and to enhance communications between state agencies and the public. The conceptual basis for the indicator system derives from the field of social indicators research and rests on the premise that explicit decisionmaking methods are more desirable than intuition and subjective methods. Four major steps were involved in developing the fisheries and wildlife indicator system. The first step was assessing the current availability of resource information and involved analyzing state fisheries and wildlife agency annual reports. Administrative information was emphasized in reports over fisheries and wildlife resources and their use. States rarely reported trend statistics that allow comparisons over time to be made. Reports contained a mixture of quantitative and qualitative information, but contained few tables and graphs compared to the amount of text. Assessing the type, quality, and quantity of performance information currently available laid the base for subsequent work on the indicator system. The second step was developing a comprehensive classification framework representing all aspects of the fisheries and wildlife resource. The framework, a 16-cell matrix including the resource categories of People, Populations, Habitat, and Administration, and the resource components of Inputs, Processes, Outputs, and Impacts, contained 82 separate resource characteristics representing the universe of concerns and responsibilities faced in state-level fisheries and wildlife management. The third step was identifying indicators representative of each characteristic in the framework. Through an extensive analysis of fisheries and wildlife literature, agency documents, and social assessment literature, 377 indicators were identified. Based on appropriateness and availability of each indicator, 242 indicators were recommended for monitoring by state fisheries and wildlife agencies. The last step in the process was describing the use of the fisheries and wildlife indicator system, how the system can fit into an agency's administrative structure and planning programs, and how its use may affect the future of fisheries and wildlife management.
Food habits, population dynamics, and bioenergetics of four predatory fish species in Smith Mountain Lake, Virginia
Moore, Christopher Miles (Virginia Polytechnic Institute and State University, 1988)
The food habits, survival rates, and abundance of four predatory fish species (striped bass, walleye, largemouth bass, smallmouth bass) were determined and combined with information on energetics and growth to quantitatively assess predator-prey interactions in Smith Mountain Lake, a large hydroelectric reservoir in south-central Virginia. A total of 1871 stomachs of the four species was examined from fish collections between April 1983 and December 1984. Food habits of each predatory species were assessed and compared by season using Schoener's (1970) diet overlap index. Significant diet overlap occurred between the pelagic predators (striped bass and walleye) and between the littoral black basses (largemouth bass and smallmouth bass) in all seasons and locations where sufficient stomach samples were collected. Survival and abundance estimates for the four predators were derived from several data sets. First-year survival of striped bass fingerlings averaged 20.8% for an 11-year period (1973 to 1983) and ranged from 3.9% to 54.3%. Average survival of age-0 largemouth bass and smallmouth bass was 53% and 45%, respectively, for the period 1979 to 1983. Species-specific survival rates for predators age 2 and older ranged from 29% to 59%. Of the predators age 1 and older, largemouth bass were the most numerous at an estimated density of 61.2/ha, followed by striped bass at 16.3/ha. Age 1 and older smallmouth bass and walleye were less abundant, at densities of 8.2 and 2.0/ha, respectively. A bioenergetics model was developed for striped bass and, with models developed for walleye and largemouth bass, used to estimate annual consumption of alewives and gizzard shad by the four piscivorous species. Annually, striped bass consumed the greatest amount of adult and young-of-year alewives, whereas largemouth bass ate nearly 70% of the total shad biomass consumed by all predators. A comparison of predator demand to clupeid supply substantiated diet overlap data; namely, that native and introduced predators were compatible in Smith Mountain Lake. The striped bass bioenergetics model was used to make inferences about potential stocking strategies for striped bass based on availability of age-1 and older alewives. A stocking rate of 20-24 fingerlings/ha appears to maximize production of striped bass and minimize potential competitive interactions between striped bass and native black bass in Smith Mountain Lake.
Habitat suitability and population characteristics of smallmouth bass and rock bass in the Powell River, Virginia
Cummins, James L. Jr. (Virginia Tech, 1994-05-15)
A survey of the population characteristics of smallmouth bass (Micropterus dolomieu), rock bass (Ambloplites rupestris), and habitat conditions were conducted in the Powell River, Virginia, to identify potential habitat limitations for these species. The study area consisted of three reaches, which were determined in 1987. The upstream reach was used to monitor effects of coal mining in the upper watershed on the Powell River. The midstream reach, which was below the North Fork Powell River, was used to monitor the possible effects of this tributary and its watershed. The downstream reach appeared to have been impacted by sedimentation less than either of the other reaches. Habitat Suitability Index (HSI) models were used to identify habitat variables that were below optimum for these species in the Powell River, Virginia. Habitat sampling yielded HSI scores for smallmouth bass at each site ranging from 0.67 to 0.76, with a mean of 0.72; scores for rock bass ranged from 0.65 to 0.70, with a mean of 0.69. No trends in HSIs from upstream to downstream were evident. However, substratum, of which sand was dominant in pools, was the variable most frequently below optimum for smallmouth bass (Sl=0.21) and rock bass (SI=0.20). Values for sediment depth, embeddedness, waterborne sediment, and coal were collected in riffles, runs, and pools at 10 sites. Mean sediment depth in pools, embeddedness in riffles and runs, and waterborne sediment deposited in traps monthly in pools decreased from upstream to downstream; however, waterborne sediment in runs did not decrease. Content (by weight) of coal wastes in the substratum did not decrease from upstream to downstream. The embeddedness index in pools (= 1.0), riffles, and runs was not significantly different among the three river reaches. No differences in population abundance, biomass estimates, age and growth, or relative weights (Wr) of smallmouth bass and rock bass were found among the three river reaches. Population estimates of smallmouth bass (34.3/ha) and rock bass (116.6/ha) were lower than those in many other streams in the U.S. Catch-per-unit-effort and biomass of smallmouth bass (2.9/h, 2.6 kg/ha) and rock bass (6.6/h, 2.2 kg/ha) also were lower than those in most other streams. A total of 70 stomachs of smallmouth bass and 166 stomachs of rock bass was examined from fish collected between July 1988 and October 1989. Diets for each species, primarily crayfish and insects, showed no apparent differences among the three river reaches. Abundance of crayfish and hellgrammites were compared; greatest hellgrammite abundance was in the downstream reach (P = 0.032), and there were no significant differences in crayfish abundance among the three river reaches. HSI values showed no significant correlation with catch-per-unit-effort for smallmouth bass or rock bass. No significant correlation was found among sediment depth, catch-per-unit effort, biomass or relative weight of smallmouth bass and rock bass. No correlation was found between the embeddedness index in riffles and biomass of rock bass. There was a significant negative correlation between the embeddedness index in riffles and relative weight of smallmouth bass (P=0.016); however, no correlation existed between the embeddedness index and relative weight of rock bass. There was a significant negative correlation between the embeddedness index in riffles and growth of smallmouth bass (P=0.016); however, there was a significant positive correlation between the embeddedness index and growth of rock bass. There was a significant positive correlation between the embeddedness index in riffles and both hellgrammite abundance (P=0.031) and crayfish abundance (P=0.052) in riffles. No significant correlation was found between the amount of sediment deposited in pools and catch-per-unit-effort of smallmouth bass and rock bass. No significant correlation existed between the amount of sediment deposited in runs and biomass of rock bass. In addition, crayfish density was not correlated with relative weight of smallmouth bass or rock bass. With the available documentation that links population characteristics of smallmouth bass and rock bass to habitat, it is evident that habitat is usually the limiting factor in determining population characteristics; however, there was no significant trend in the correlations presented above. Habitat for smallmouth bass and rock bass in the Powell River, Virginia was suboptimum and sand was the dominant substratum in pools. Population estimates, catch-per-unit-effort, and biomass of smallmouth bass and rock bass in the Powell River are low compared to other U.S. streams. Although it appears that sedimentation has degraded habitat of smallmouth bass and rock bass and contributed to reduced population levels of these species in the Powell River, Virginia, my results were not statistically different among sites with measurable differences in sedimentation.
James River Mainstem Investigation: Executive Summary
Garman, Greg C.; Smock, Leonard A.; Nielsen, Larry A.; Orth, Donald J.; King, Mark A.; Stanovick, John J. (1991-07)
James River Mainstem Investigation: Fisheries Yield Model
Garman, Greg C.; Smock, Leonard A.; Nielsen, Larry A.; Orth, Donald J.; King, Mark A.; Stanovick, John J. (1991-07)
James River Mainstem Investigation: Recreational Use
Garman, Greg C.; Smock, Leonard A.; Nielsen, Larry A.; Orth, Donald J.; King, Mark A.; Stanovick, John J. (1991-07)
Larval fish abundance and habitat associations in backwaters and main channel borders of the Kanawha River
Scott, Mark Thomas (Virginia Tech, 1988-11-15)
Larval fish distributions were determined in the lower Winfield Pool, Kanawha River, West 85, Virginia, using a 0.5-m plankton net and a 1-m² dropbox. Five habitats were sampled with the plankton net, 3 habitats with the dropbox. The 5 deep water water habitats, greater than 1.5-m in depth, sampled by the plankton net included surface tows in Bill's Creek backwater, main channel border upstream and downstream of Little Guano backwater, and Little Guano Creek backwater, where deep tows (1.5 m deep) were also taken. The 3 shallow water habitats, less than 1 m in depth, sampled by the dropbox included open water over silt substrate, open water over a sand substrate, and emergent vegetation. Lepomis species, emerald shiners (Notropis atherinoides), and gizzard shad (Dorosoma cepedianum) were the dominant taxa. The emerald shiner taxa could also have included some larvae of Notropis species which are also present in the Kanawha River but whose larvae have not been described. Overall, the mean total larval density did not differ between the backwater or the main channel borders but the species associated with each habitat differed greatly. The Lepomis larvae were found predominantly in backwater areas. These areas provide suitable spawning sites for many centrarchids of this river. Upon leaving the nest, the Lepomis larvae moved into the deeper open water areas within the backwater. After reaching the juvenile stage, these same larvae returned to the shallow water habitats where they inhabited vegetated areas. Emerald shiner larvae, while present in both backwater and main channel habitats, were most abundant in the main channel borders. This is probably a result of their parent's pelagic spawning strategy. In all habitats, emerald shiner larvae predominated in the upper 1 m of water. Upon becoming larger, the emerald shiner larvae appeared in the backwaters. This increase in numbers could be due to movement, differential mortality, or higher growth rates. Other cyprinids (excluding emerald shiners and carp) were equally abundant in both backwater and main channel areas. These other cyprinid larvae were also distributed equally, Gizzard shad larvae were found predominantly in the main channel borders. Presumably, these higher densities were the result of main channel spawning. The gizzard shad larvae present in the backwater areas were distributed evenly throughout the water column. Overall, the backwaters were important for the nest-building species found in the river and also for the larger larvae of the pelagic species, and thus acts as a nursery area for these species. Therefore, the backwaters do seem to be important for the fishery of the Kanawha River.

Browsing by Author "Nielsen, Larry A."

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