54 Years of Monitoring and Assessing Ohio River Fish Populations

The Ohio River Valley Water Sanitation Commission (ORSANCO) is an interstate water pollution control agency that operates programs for water quality monitoring and assessment, spill detection and notification, pollution control standards, and public information and education.  Biological sampling has been one aspect of monitoring and assessment since 1957.  Historically, biological sampling consisted of collecting fish community information from lockchamber rotenone sampling, which has provided an extremely useful dataset for assessing long-term trends in fish community condition. From the first surveys in 1957 to the last collections in 2005, 384 lockchamber sampling events had been conducted resulting in the collection of over 3 million fish comprised of 167 species.  Beginning in 1991 ORSANCO began exploring nighttime boat electrofishing as a supplemental technique to the lockchamber surveys.  For a variety of reasons, boat electrofishing quickly became the primary collecting technique for providing data for the routine monitoring and assessment efforts.  From 1991 to 2010, 1,788 electrofishing events, each 500 meters long, have been conducted resulting in the collection of 406,303 fish from 118 species.  In 2003, a subset of these collections was used to create an Ohio River Fish Index (ORFIn) which was useful in the assessment of the Ohio River’s Aquatic Life Use for 305(b) reporting.  Using an updated subset of these collections, the ORFIn has since been modified (mORFIn) incorporating continuous rather than discrete scoring methods and directly incorporating instream habitat into the final index scores.  Besides lockchamber rotenone and boat electrofishing surveys, benthic trawling had also recently been explored as a useful fish sampling technique on the Ohio River.  From 2006-2008, four trawl hauls (each 1-2 minutes in duration) were conducted at each of 146 locations which were also sampled via boat electrofishing within six months of trawling.  Trawling sampling resulted in 3,250 individuals from 33 fish species.  Future monitoring and assessment protocols will consist of night-time boat electrofishing surveys annually at 15 randomly drawn 500 meter sites in each of four navigational pools as well as at 18 riverwide fixed stations which have been sampled each year since 2004.  In addition to fish collections at each sampling site, macroinvertebrates, water and sediment chemistry, and instream and riparian habitat data will be collected to holistically assess the condition of the aquatic life of the Ohio River.