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ESTIMATION OF SURPLUS BIOMASS OF CLUPEIDS IN SMITH MOUNTAIN LAKE, VIRGINIA
Citation:
Cyterski, M J., J. Ney, AND M. Duval. ESTIMATION OF SURPLUS BIOMASS OF CLUPEIDS IN SMITH MOUNTAIN LAKE, VIRGINIA. TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY 132(2):361-370, (2003).
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:
Mean annual estimates of surplus biomass of alewife Alosa pseudoharengus and gizzard shad Dorosoma cepedianum in Smith Mountain Lake, Virginia, were calculated using data on the biomass, growth, and mortality of each clupeid species. Surplus biomass, defined as production over a time period, less the difference between biomass at the end and beginning of the time period, was determined for each cohort of both prey species. Mean total alewife biomass estimated from hydroacoustic surveys during 1993-1998 was 37 kg/ha. Mean total gizzard shad cove rotenone biomass from 1990-1997 was 89 kg/ha. Coupling biomass with estimated growth and mortality rates, mean annual alewife and gizzard shad surplus biomass, summed across all cohorts, was 74 kg/ha and 116 kg/ha, respectively. The surplus biomass of alewife barely meets piscivore demand (primarily largemouth bass Micropterus salmoides and striped bass Morone saxatilis) while predator demand might exceed gizzard shad surplus biomass when prey availability is taken into account.