SummaryRelative abundance trend of key indicator species at different life stages (i.e. Delta smelt, Longfin smelt, juvenile striped bass, Chinook salmon, all salmonid populations). General Information about this IndicatorWhat is it?: The well-being of regulated and culturally-important fish species is important to measure in order to understand ecosystem condition, as well as actual and potential regulatory issues associated with water management. Both abundance and trends in abundance can be used.