Investigations of the Cause of Fishkills in Fish-Rearing Facilities in Raven Fork Watershed

摘要

An investigation was undertaken to determine the cause of fishkills in trout-rearing facilities located adjacent to Raven Fork Creek within the Cherokee Indian Reservation in North Carolina. Approximately 50,000 rainbow trout were lost at the Blankenship trout farm-a commercial facility-following eight storm events between March 31 and December 2, 1981. In addition, 524 trophy-size trout died in three ponds operated by the Cherokee tribe for stocking reservation streams. It was found fishkills in the trout farm could be prevented by adding lime to water from the creek as it was pumped into the facility; this strengthened the assumption acidity (H exp + ) was responsible for the fishkills. Mortality of trophy trout was stopped by routing water from nearby springs to the ponds during and following rain events. Because of concern that these fishkills might be caused by acid rain, TVA was requested by the Cherokee tribe to assist in determining the cause. Limited studies were conducted during March through August 1982 to test two hypotheses: (1) concentrations of H exp + and soluble aluminum in Raven Fork following storm events were high enough to kill rainbow trout and (2) atmospheric deposition was a greater source of stream H exp + than acid-producing geologic formations or the forest soils. (ERA citation 08:047484)