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.

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. / Master of Science