Cooperative Fish and Wildlife Research Units Program: South Carolina
Education, Research and Technical Assistance for Managing Our Natural Resources

South Carolina Project

Quantifying the Effect of Instream Flow on Larval Fish Abundance in the Edisto River Basin

March 2020 - December 2021


Participating Agencies

  • South Carolina Water Board

Instream flow variability is widely considered as one of the principal factors shaping riverine ecosystems and biodiversity. Environmental variation linked with hydrology and seasonality interact with life history strategies of fishes to determine phenology of spawning in riverine systems. This study examines the patterns of larval fish abundance in relation to discharge and microhabitat water velocity to better understand fish spawning phenology and its connection to hydrology. From May 2021 to July 2021, we sampled larval fish weekly in Twelve Mile Creek using larval fish seines. We collected discharge data from an upstream USGS gage and microhabitat data was collected at each sample point within a 200m stream reach. We identified all larval fish specimens to family and measured their standard length. We detected temporal patterns in larval fish abundance, with peak Percidae and Leuciscidae abundance in late July and the highest Catostomidae abundance in late May-early June. We found Percidae abundance was associated with greater maximum discharge and increase variation in discharge, Leuciscidae was negatively related to mean discharge, and a negative association between Catostomidae abundance and variation in discharge. We also detected a positive association between Percidae abundance and microhabitat depth. Overall, our results suggest that the spatial and temporal patterns of larval fish abundance are influence by river hydrology and microhabitat variables.