Public and private concern over the decline of Virginia's oyster industry prompted the General Assembly (GA) in 1977 and 1983 to commission its Joint Legislative Audit and Review Commission (JLARC) to examine the State's oyster grounds management policies. In response to JLARC's findings the GA directed Virginia Marine Resources Commission (VMRC) to construct and implement an oyster fisheries management plan. The GA set as the plan's objective to achieve the greatest production level possible subject to limits of physical resource availability and technical feasibility. That the plan should be attentive to cost-effectiveness was also expressed by the GA. In developing its management plan VMRC must consider a variety of environmental, economic and political factors affecting the production and harvest of market oysters. A linear programming model developed for VMRC's use in evaluating alternative oyster grounds management strategies is described. The objective of the programming model is to minimize the public plus private cost of producing a prespecified level of market oyster harvest over a ten year planning horizon. The model includes as its activities the different aquacultural techniques used by private planters and VMRC in its repletion program. The many environmental, economic and political factors are incorporated into the model's constraints and technical coefficients. Several management alternatives are evaluated with the model. The results of these analyses indicate that without a fundamental in the oyster repletion program, even if new oyster grounds management policies are considered, there would be little change in public grounds market oyster harvest over current levels. Under revised repletion program practices, however, marked increases in public grounds harvest could be effected for relatively small increases in repletion program budget allocations over current levels. / Master of Science

The Virginia oyster industry changed markedly in the period between 1950 and the present. This change has been the result of a variety of forces which can be conveniently classified as economic, biological and institutional. In general, biological forces initiated a series of changes in the fishery which have had economic impacts and impacts on the institutional structure of the fishery. The biological forces have had a much more severe impact on the seed-planting, or private grounds, sector than on the public grounds sector. The dependence of the seed planting sector on public seed beds and the different regulatory regimes applicable to the public and private grounds makes it difficult to draw firm conclusions on the relative merits of alternative tenure structures. The magnitudes of economic, biological and public policy forces as contributing factors to the decline of the oyster fishery are estimated and it is concluded that the biological forces have played the dominant role in the decline of the Virginia oyster fishery. It is suggested that attention be focused on the physical and management inputs to the production of oysters and on methods for bringing forth an appropriate resource mix. It is argued that either a predominantly private grounds fishery, a predominantly public grounds ‘' fishery, with appropriate institutional modifications to allow efficient harvest technologies to be used without threatening the viability of the resource base, or a mixed tenure system could be used and with appropriate management could result in substantial revitalization of the Virginia oyster industry. However, because of the biological changes which have occurred, management, whether public or private, takes on a much more important role in determining the future of the Virginia oyster fishery. / Ph. D. / incomplete_metadata

In recent years, the blue crab fishery has become the main source of income for Virginia's watermen. This fact, along with growing concerns of overharvesting and uncertainty about the amount of effort in the fishery, has led to calls for more complete data on the fishery. This study examined the characteristics of Virginia's blue crab fishery, through an extensive survey of crab pot license holders conducted on a monthly basis from March to November of 1992. Along with a description of the people in the fishery, this study also modeled prices, harvest levels, and income levels for the blue crab industry. Because the models were interactive in nature, the effects of various fishery management strategies were also analyzed. The main emphasis of the policy simulations was to discover what impacts the different strategies had on harvest and income levels. The results of the simulations showed that many of the policies currently under consideration will have only a small impact on overall harvest and income levels, but there are some larger distributional effects among different firm classes. The findings of this study suggest that in order to gather accurate and useful data on the fishery, the random surveying techniques of this study should be continued over a period of years. / Master of Science

Phosphorus is often the limiting nutrient of primary productivity in southern Appalachian reservoirs, but its impact on higher trophic levels has not been assessed. Regression analysis was used to examine the relationship between total phosphorus concentrations and estimates of fish standing stock in Smith Mountain Lake (SML) over time and for 22 southern Appalachian reservoirs (SAR) at the same time. ln SML, which had responded to a nutrient reduction program, total phosphorus concentration and fish biomass concurrently declined over an 12-year period; phosphorus concentration accounted for one-third (cove-specific) and two-thirds (whole-Iake) of the annual variation in fish standing stock. Total phosphorus concentration was also the best predictor of fish abundance in SARs, accounting for 84% of the variation in standing stock despite great diversity in reservoir physical, chemical, and biological characteristics. Predictive power was generally higher at lower levels of the food chain (i.e. planktivores, younger fish) than for piscivores. Planktivore response to phosphorus was found to be immediate. Piscivore biomass did not vary significantly with phosphorus, owing in part to poor energy transfer up the food chain and variable management practices. Phosphorus concentration and total fish standing stock appear to have stabilized in SML since 1980. Losses in fish standing stock due to deceased fertility in SML have been partly offset by an increase in coolwater habitat. Aesthetic versus fishery benefits and the complexity of dealing with a longitudinal trophic gradient need to be considered for future management of SML. / Master of Science / incomplete_metadata