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TROPHIC DYNAMICS OF STRIPED BASS IN SMITH MOUNTAIN LAKE, VIRGINIA
Citation:
Cyterski, M J. AND J. Ney. TROPHIC DYNAMICS OF STRIPED BASS IN SMITH MOUNTAIN LAKE, VIRGINIA. Presented at American Fisheries Society Annual Meeting, Baltimore, MD, August 18-22, 2002.
Impact/Purpose:
This research project sets out to design and conduct an assessment of the long-term ecological consequences of alternative watershed management choices. As the first project to be done at this scale using predictive ecological endpoints, we will seek to identify the appropriate components of such an analysis. We will use experience gained in the conduct of this analysis to identify key research and data needs for future analyses. We will extend this analysis beyond previous and ongoing studies in two ways: by incorporating biological endpoints, primarily properties of fish communities, and by introducing the concept of sustainability of ecological state under future scenarios contrasted with the present state of those same ecological resources. Requirements that are identified during the course of this study will permit the recommendation of specific capabilities that should be incorporated in a general modeling system currently under development to support environmental assessments. Finally, the analysis is intended to be of value for establishing environmental management choices that will be beneficial and those that would be detrimental to the sustainability of ecological resources. Specific objectives are listed below:
1. Develop watershed-based modeling systems to forecast the effectiveness of alternative management plans in meeting sediment-related, nutrient-related, pathogen-related, and toxics-related criteria and standards, and biologically-based criteria and standards; and
2. Develop and maintain a comprehensive technical support capability that directly links environmental TMDL exposure research activities and products for the EPA Office of Water, EPA Regional Offices, and the States to be used for implementation of policy, regulatory development, remediation, and enforcement needs.
Description:
We examined the adequacy of the forage base to meet demand of striped bass in Smith Mountain Lake, Virginia. In regards to prey supply, mean alewife biomass from 1993-1998 was 37 kg/ha and mean gizzard shad biomass from 1990-1997 was 112 kg/ha. Mean annual alewife surplus production was 73 kg/ha and mean annual gizzard shad surplus production totaled 146 kg/ha. Bioenergetics modeling coupled with population density estimates showed that striped bass consumed 46 kg/ha of alewife and 27 kg/ha of gizzard shad annually. The cumulative effect of morphology, behavior, and distribution on prey availability, in addition to consumption by other predators, was also quantified. For striped bass, available supply of gizzard shad surpassed demand by 30% but available alewife supply was only 4% greater than demand. Striped bass stockings were increased by 50% in 1998 and have remained at that level. A model that simulated the relationship between alewife abundance and mortality and the mortality, abundance, and growth of striped bass examined the consequences of increased striped bass stocking. Model output showed that a stocking increase had a near-zero probability of increasing the mean density of legal and citation striped bass in this system.