R/FISH-101

Strategic focus area:

Description:

OBJECTIVES: The objectives of this study are to: 1) demonstrate proof of concept utility of BIA as a measure of nutritional status of Chesapeake Bay striped bass; 2) determine the relationship between BIA and observable body fat (BFI) to enhance the utility of historically collected data; 3) transfer the technology and established biological reference points to state resource management agencies; and 4) strategically implement BIA as part of MDNR's ongoing, routine health surveys in support of EBFM. Our working hypothesis is that proven technology based on resistance will provide an accurate, non-lethal means of estimating nutritional health of striped bass. The development of this approach will not only allow for the application of an annual index in support of EBFM, but facilitate future efforts in understanding trophodynamics and impacts in Chesapeake Bay.

METHODOLOGY: Our earlier work developed both a metric (lipid%) and a tool (BIA) to assess health of the striped bass population in Chesapeake Bay. In this proposal we complete the development of a model to estimate lipid% using impedance measures of striped bass. BIA measures were recently completed on 100 striped bass. We will conduct proximate analysis on these fish and develop statistical models to predict lipid%. We will validate the BIA models in year 1 using wild striped bass as part of MDNR surveys. Striped bass will be collected and necropsied by MDNR and we will collect BIA measures and tissue samples to estimate lipid levels from established relationships. Validation procedures will compare the ability of BIA to estimate lipid levels, determine degree of accordance between BIA and BFI measures, and evaluate sex or size influence on estimates. The technology will be transferred to managers for monitoring in Year 2.

RATIONALE: Crucial to effective ecosystem and species management decision making is the need for nutritional health indicators to assess the implications of changes in ecosystem trophodynamics. The energy reserves of individual fish and populations are essential in defining impacts of system-wide trophodynamic changes as they relate strongly to foraging success, potential prey density, habitat availability, environmental stressors, and subsequent fish health. An appropriate indicator must be easy to measure, sensitive to change, and have strong reference points and thresholds to trigger management decision making. We have developed biological reference points for nutritional health of Chesapeake Bay striped bass for use in EBFM and non-lethal methods for measurement. We propose to build upon these efforts by validating the use of bio-impedance analysis and observational indices for estimating lipid content in striped bass and transitioning the methodology to coastal resource managers by involvement in the validation effort, workshops, trainings sessions, and protocol publications.