TWENTY-SECOND ANNUAL EASTERN FISH HEALTH WORKSHOP ROYAL PAVILLION RESORT, ATLANTIC BEACH, NC MARCH 18 - 20, 1997 Multiple Factors Contributing to Morbidity and Mortality at a Pennsylvania Trout Hatchery Bill Lagoda, Lynda Champlin, and Fred Rommel State Veterinary Laboratory, Pennsylvania Department of Agriculture, Harrisburg, PA 17110 A trout hatchery in Pennsylvania began to experience serious mortality in November 1996. Heavy rains in September caused severe flooding. By November 7-10,000 fish had died. The facility maintains its own broodstock. All rainbow eggs perished. Additional rainbow eggs were purchased from Trout Lodge. Brook and brown trout eggs were obtained from broodstock after the flooding. The facility first requested assistance in December and brought a small number of live trout (a mix of mostly brown and some rainbow and brook) to the laboratory. Gross appearance included lethargy, open lesions, severe fin erosion and obvious saprolegnia. The fish were heavily infested with Ich and Gyrodactylus. Subsequently Yersinia ruckeri was isolated from the kidney of one fish. IPN was found in low numbers of 102.3-3.3 TCID50/mL. Several weeks later a visit was made o the hatchery site and additional fish (yearling rainbow and a mix of mostly brown and some brook) were collected. Parasite infestation of Gyrodactylus was even heavier but the Ich was subsiding. Aeromonas salmonicida was isolated from kidneys of several fish. Motile Aeromonas sobria and A. veronii were isolated from lesions. Prior to seeking assistance from the laboratory, treatments included formaldehyde and medicated feed (terramycin and romet 30). Measurements were made of water quality. The hatchery reputedly had a nitrogen problem from the spring water source. Additional examination of fish in the hatchery house and in the upper raceways are in progress. Return to 22nd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page