Characterizing Environmental and Physicochemical Conditions in Nursery Areas of River Herring in Chowan River, North Carolina

Abstract

Anadromous fishes such as blueback herring Alosa aestivalis and alewife A. pseudoharengus, utilize sounds, rivers, and tributaries during spawning. Collectively known as river herring, these two ecologically important species spawn in Chowan River, North Carolina. River herring have been important commercially since the early 1900s. Over time, overfishing, declining water quality, and degradation of habitat likely caused population declines resulting in a moratorium in the state of North Carolina in 2007. This study examined how water quality and water chemistry of Chowan River influenced larval river herring abundance, health, and nutritional condition. I hypothesized that variability in abiotic conditions could structure nursery habitat into groups based on river herring abundances. Ichthyoplankton samples were collected weekly from March 18 through May 26, 2011 at nine stations in Chowan River basin. Biologically higher abundances (number/100m³ ± SD) of river herring were found in two creeks, Catherine's Creek (1583 ± 2698) and Wiccacon Creek (1316 ± 3027), when compared to the remaining sites (mean = 182 ± 384). Nutrient values (mean concentration ± SD), chlorophyll [alpha] (6.17 ± 6.23), phosphate (0.022 ± 0.019), and organic nitrogen (0.21 ± 0.012) were related to habitat with higher larval fish abundance. Larval nutritional condition does not seem to be significantly correlated with these physicochemical factors; however, standard lengths of larvae are significantly longer in high abundance sites. Results from this study will aid state agencies in completing surveys of larval river herring abundance in Chowan River and will also aid management agencies in sustaining and rebuilding nursery habitat for river herring and many other species in Chowan River, NC and other bodies of water.