2005 Annual Report 4d.Progress report. This report documents research conducted under a Specific Cooperative Agreement between ARS and University of Mississippi. Additional details can be found in the report for the parent research project 6402-13320-003-00D, Optimizing Catfish/Water Quality Interactions to Increase Catfish Production. Development of effective inventorying methodologies is critical for the future of the catfish industry. National Center for Physical Acousitics (NCPA), Univ. of Miss. collaborated with Mississippi State University-Delta Research and Extension Center (MSU-DREC) and MS Valley State Univ. as well as some commercial operators Harvest Select Inc., Jim Murphy Farms to operate the Aquascanner Catfish SONAR to determine its effectiveness for performing such an inventory. This testing has confirmed that meteorological factors (wind and temperature gradients in the pond) as well as pond bottom features have a substantial impact on the SONAR's operation and fish enumeration. As signal processing routines and data acquisition techniques are improved, this SONAR system could act as a valuable tool for pond inventorying.