1. US Geological Survey, National Fish Health Research Laboratory, Leetown Science Center, Kearneysville, WV 25430, USA
2. Pennsylvania Sea Grant College Program, Pennsylvania State University, Erie, PA 16505, USA
3. Pathology Department, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
4. Pennsylvania Fish & Boat Commission, Division of Fisheries Management, Harrisburg, PA 17106, USA