No description available.

Lake Moomaw, a 1,024-ha flood control reservoir in Bath and Allegheny counties, Virginia contains a migratory population of smallmouth bass that congregate in the headwaters of the reservoir during the spring spawning period, where they are vulnerable to a shore-based, harvest-oriented fishery. The extent of this fishery and resulting effects on the small mouth bass population were analyzed by means of a creel survey in the headwaters area during the spring spawning seasons of 1995 and 1996. Effort, catch, and harvest, as well as user characteristics and motivations data were obtained from direct interviews with anglers using this area. Estimates for 1995 indicated extensive fishing pressure per ha, with 1,167 angler hours per ha spent fishing for smallmouth bass in the headwaters, while in 1996 almost 1,400 angler hours per ha were spent in this area. Catch and harvest rates were relatively low and sustainable during both years, with 124 small mouth bass caught and 82 harvested in 1995, while 318 small mouth bass were caught and 222 harvested in 1996. An extensive capture-recapture study yielded estimates of exploitation rates for small mouth bass in the reservoir of 12- 15% annually. Exploitation of the whole-lake population occurring in the spring headwaters fishery was estimated at 4-6%, while the exploitation rate on the subset of the population using the headwaters during the spring was 11-14%. Analysis of movements of snlallmouth bass in the reservoir using ultrasonic telemetry and dart tag recaptures indicated that the subset of the population using the headwaters was mainly drawn from the upper and middle portions of the reservoir, and that significant amounts of spawning occurred in the lower section of the reservoir as well. Areas used by smallmouth bass for reproduction were documented with summer and fall electrofishing to determine relative abundance of young-of-the-year smallmouth bass in the reservoir, and showed spawning to take place throughout the reservoir. Densities of young-of-the-year shifted as fall progressed, with highest densities in the middle portion of the reservoir in early fall, indicating that reproductive inputs from the headwaters were realized in the lake as fall progressed. The headwaters fishery is a high-profile activity which, during 1995-96, had a low and sustainable impact on the Lake Moomaw smallmouth bass population. / Master of Science

No description available.

The influence of physical parameters on spawning times of smallmouth bass and subsequent growth of young-of-the year was studied via the otolith aqeinq technique. Daily rings on the saqittae of young-of-the-year smallmouth bass were first formed the day of swim-up, and continued to be formed until growth was significantly reduced in the fall. Daily age estimates of young-of-the-year smallmouth bass collected from one unregulated section of the New River, two regulated sections of the New River, and two tributary streams of the New River were used to back-calculate spawning dates. Growth rates of young-of-the-year declined as fish got older. Smallmouth bass spawned early in the spawning season did not initially grow as rapidly as those spawned later. Spawning occurred from late-April through mid-July, 1982, at mean daily water temperatures ranging from 12.5 to 23.5 C. Frequency distributions of spawning dates were nearly identical among study sites, as were hydrological events. A major flood in June separated the spawning season at all study sites into t)lo distinct periods. Discriminant functions were developed from four water temperature variables that differentiated between daily stream conditions prior to the spawning season and daily stream conditions during the spawning season. Mean daily water temperature was the most important of the four variables in differentiating between groups of conditions. / Master of Science

Smallmouth bass (Micropterus dolomieu) were collected from a reach of the James River, Virginia undergoing American shad (Alosa sapidissima) restoration and fish passage projects. Diet and growth of these specimens were compared to specimens collected prior (1987-1990) to American shad restoration and fish passage. The Piedmont James River was stocked with >5 million American shad larvae annually since 1995 and was re-opened to migratory fish in 1999. Mean lengths-at-age (ages 1-4) were back-calculated from scales and compared using the Mann-Whitney Test. Smallmouth bass collected in 2002 had a significantly lower mean length-at-age for age 2 specimens compared to 1987-1989 smallmouth bass (P=0.04). Stomach contents were placed into four major categories (fish, crayfish, aquatic insects, terrestrial insects) and compared using Schoener's Diet Overlap Index. Schoener's Index produced a score of 0.94; indicating very high diet overlap. In 2002, Centrachidae was the dominant fish prey family and redbreast sunfish (Lepomis auritus) was the dominant species. American shad was not observed in stomach samples during 1987-1990, but was the second most common fish species prey species identified in 2002. Recovery of American shad from smallmouth bass indicates smallmouth bass are utilizing forage produced by restoration stockings. No semi-migratory fish species using new fish passage structures were recovered fiom smallmouth bass stomachs. Fish prey was measured by weight, number of items, and by occurrence; and placed in six family categories for comparison. Schoener's Index produced scores ranging from 0.26 for prey weight to 0.40 for prey occurrence, indicating low fish prey diet overlap. These data indicate that smallmouth bass are utilizing new forage resulting from restoration activities, but growth rates have not changed significantly. Smallmouth bass may not be forage-limited in the study area.

No description available.

No description available.

This study examined the relationship between microhabitat use and growth of age-0 smallmouth bass in the North Anna River. The study objectives were to describe microhabitat use during summer, assess the profitability of microhabitats, and determine if and how microhabitat use could determine which individuals gained a growth advantage. Age-0 smallmouth bass changed their microhabitat use as they passed through stages of ontogenetic development and became familiar with their environment. More than 30% of the area available to brood larvae contained mean water column velocities greater than 4 cm/s and no cover. More than 80% of larvae observed after dispersing from the nest site occupied areas approximately one m deep with velocities near 0 cm/s, or large cover objects that created low velocity shelters throughout the water column. By six weeks after dispersal (when all juveniles were > 40 mm), more than 50% of juveniles occupied depths less than 60 cm and focal point velocities > 3 cm/s, and microhabitat use by large and small juveniles did not differ. In these shallow microhabitats with moderate to fast current velocities, juveniles foraged at a higher rate (5.1 bites/min on average) than in deeper and slower velocity areas (1.3 bites/min). When these foraging rates were translated into estimates of energetic profit, juveniles in the shallow-fast microhabitats gained approximately 5 j/min more than juveniles foraging in other microhabitats. Microhabitat use was the only aspect of behavior that affected the foraging rate or energetic profit gained by juvenile smallmouth bass. I examined daily rings on otoliths to track the growth of individual smallmouth bass through time. Temperature affected growth rates below 22-23°C, so that individuals spawned later grew in warmer thermal regimes and grew relatively fast during early life stages. However, individuals that spawned early and grew slowly in cooler temperatures did not suffer higher mortality and compensated for their slow growth by accumulating growth over a longer period of time. Above 22-23°C, relative growth rates were not consistent through time; a fast growing individual during one life stage could grow relatively slow during the next. If growth above the temperature threshold depended on foraging success and foraging success depended on microhabitat use, then few individuals were consistently occupying the most profitable microhabitats. In experiments in an artificial stream, juvenile smallmouth bass assessed the potential profitability of an area by the foraging rate they achieved there. They usually did not remain in an area unless they foraged well at the time they searched it, and did not appear to associate habitat characteristics with profitability. In the river, most of the microhabitats available were relatively unprofitable, so an individual that abandoned a profitable area might (depending on its foraging behavior) spend Significant time in unprofitable microhabitats and consequently reduce its growth rate. Increasing the availability or density of food resources may improve growth of juvenile smallmouth bass in the North Anna River by increasing the rate at which juveniles encounter profitable microhabitats and elevating their intake rates in profitable areas. / Ph. D.

Potential predation between fishes of recreational interest has incited many bitter conflicts between angler groups. Large predators, such as esocids, are often at the center of these conflicts because of their capacity to alter fish populations. Such a conflict certainly exists between the Muskellunge Esox masquinongy and Smallmouth Bass Micropterus dolomieu fisheries of the New River, Virginia. Following the institution of a 42-in minimum-length limit (MLL) on Muskellunge, bass anglers feared that increased Muskellunge abundance might be negatively affecting Smallmouth Bass via increased predation. In order to ascertain the impacts of the 42-in MLL, I estimated the demographics, abundance, and food habits of Muskellunge combined with bioenergetics modeling to assess changes (i) in the quality of the Muskellunge fishery and (ii) in Muskellunge predation on Smallmouth Bass. Additionally, given the likelihood of future regulations to incite similar concerns from bass anglers, I modeled alternative length-limit regulations (iii) to assess their potential to improve fishery quality, thereby laying the groundwork for managers to address angler concerns before they arise. I found substantial increases in population size structure and in average adult density of Muskellunge since the institution of the 42-in MLL, but bioenergetics modeling did not indicate a notable increase in the consumption of Smallmouth Bass. I also found that high MLLs (e.g., 48-in) were likely to promote the largest increases in trophy production of Muskellunge compared to low MLLs or protected-slot limits (PSLs). This study suggests that the current Muskellunge population likely plays a small role in shaping Smallmouth Bass population dynamics and production in the New River; and lays the groundwork for predicting how the impact of Muskellunge on Smallmouth Bass might change under alternative regulations. / Master of Science

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. / Master of Science