Authors: Katie Russell, Kim de Mutsert

River herring, the collective name for Alewife (Alosa pseudoharengus) and Blueback Herring (A. aestivalis), are anadromous fish that utilize Potomac River tributaries to spawn from mid-March to mid-May. In recent decades, river herring populations have declined drastically. This study examines the size of anadromous river herring spawning populations in three Potomac River tributaries - Cameron Run (CR), Pohick Creek (PC), and Accotink Creek (AC) and how water quality variables correlate with larval and adult river herring. Each creek experiences different amounts of human activity, from high to low urbanization (CR, PC, and AC, respectively). Additionally, CR and PC receive treated wastewater discharge, while AC does not. From 2015-2019 larval and adult herring were surveyed, along with water quality parameters, to determine if human activities (i.e., effluent and urban runoff), influenced river herring population size and water quality parameters including water temperature, pH, dissolved oxygen, and specific conductivity. For data collected in 2019, ANOVAs were used to compare the catch per unit effort in the three creeks. Initial results suggest that PC had the largest population of river herring likely due to the elevated water temperatures generated by the effluent, as Blueback Herring generally select warmer rivers for spawning. Linear regressions were then used to determine linear relationships between water quality parameters and river herring abundance from 2015-2019. A significant positive correlation was found between both larval Blueback Herring (p=0.02) and Alewife (p=0.01) abundance and water temperature from 2015 – 2019. This correlation supports the suggestion that the largest spawning population of river herring in PC is related to the temperature increase caused by the treated wastewater effluent. This also suggests that the wastewater is treated sufficiently to support river herring populations. Other non-linear relationships between larval and adult river herring abundance and water quality parameters including pH, dissolved oxygen, and specific conductivity are currently being examined.