Expanded research detects

two new fish diseases

Increased disease surveillance identified two new fish pathogens that could affect the $7 billion Great Lakes fishery.


Disease can decimate fish populations by causing massive die-offs. The 2003 discovery of a new strain of viral hemorrhagic septicemia (VHS) in the Great Lakes caused concern among fisheries biologists. The disease, which has been called Ebola virus for fish, can cause widespread mortality in infected fish populations. With funding from the Great Lakes Restoration Initiative, the U.S. Fish and Wildlife Service’s Fish Health Center in Lamar, Pa., expanded its fish health and disease surveillance program in the lower Great Lakes basin, which includes Lake Erie and Lake Ontario. The project determined the geographic range and prevalence of VHS in the lower Great Lakes basin (the virus has been detected throughout the Great Lakes region). The project also expanded monitoring for exotic and emerging fish diseases in Lakes Erie and Ontario.

A related project enabled the Fish and Wildlife Service to expand monitoring of lake trout health in the lower Great Lakes basin. Scientists at the Fish and Wildlife Service’s Lamar Fish Health Center worked with researchers from the New York Department of Environmental Conservation, Pennsylvania Fish and Boat Commission, and the U.S. Geological Survey to collect and test 1,452 fish representing 15 different species. The fish were collected from 27 sites in Lakes Erie and Ontario and examined for the presence of VHS and other diseases.

Resource Challenges Addressed

  • Fish disease
  • Need for disease surveillance
  • Need for improved general fisheries management


Lake trout underwater

Lake trout, like this one here, will benefit from more effective disease monitoring. Credit: Mike Seider U.S. Fish and Wildlife Service.

Results and Accomplishments

The studies didn’t find the new strain of VHS at any new locations or in other host species of fish. But the research did reveal two new diseases that could affect wild fish stocks of salmon and trout in the Great Lakes: Lake trout herpesvirus and Nucleospora salmonis. Nucleospora salmonis was confirmed in two steelhead trout from Lake Erie, one collected at Trout Run Weir and the other from Chautauqua Creek. Testing for pathogens continues on archived samples. Another 500 lake trout that were for use in fisheries restoration programs the Great Lakes were tested at the Lamar Fish Health Center and found not to have these diseases.