Department of Natural Resources
Piscirickettsia - A New Pathogen in Lake St. Clair Muskies - A Fact Sheet of our Current Knowledge
Resource Background: The muskellunge fishery of Lake St. Clair has a reputation among muskie anglers for unusually high catch rates. The fishery draws anglers from the local area as well as from across the continent. Numerous charter fishing businesses specialize in muskie trips. Countless individual anglers fish exclusively for muskellunge while the season is open. A large Detroit area angling club is dedicated to the sport of muskie fishing. Many Lake St. Clair muskellunge anglers espouse a strict catch-and-release ethic. The Lake St. Clair muskellunge fishery is completely self-sustaining, thus any threat to the continued successful recruitment of muskellunge in the lake is a serious concern for fisheries managers.
Pathogen Detection in Lake St. Clair: : In May of 2002, the Michigan Department of Natural Resources (MDNR) collected several muskellunge exhibiting unusual red skin rashes from the Anchor Bay area of Lake St. Clair. The rounded rashes reached up to one inch in diameter (Figure 1). Laboratory analysis at Michigan State University by Dr. Mohamed Faisal, revealed the association of these lesions with a Gram-negative, curved, intracellular bacterium that occurred as rings or curved rods (Figure 2). Based on their shape and culture characteristics, the organism was determined to be a Piscirickettsia-like organism.
Pathogen Impacts in Lake St. Clair: While the Piscirickettsia-like organism has been found in Lake St. Clair, DNR surveys and reports by fishermen have not indicated negative impacts in the muskellunge fishery.
Fisheries Division Action Plan: The discovery of this infection in Lake St. Clair muskellunge has raised the following questions:
In response to public concerns, the DNR has assembled a team of fishery biologists, managers, and specialized veterinarians that continue to monitor this case. Muskie anglers wishing to assist in this effort and anglers that catch a muskie in Lake St. Clair bearing red sores similar to those shown below are asked to report their observation to the Lake St. Clair Fisheries Research Station using the following contact information.
For more information on Piscirickettsia in Lake St. Clair's muskellunge:
Todd Wills, Area Research Manager
Lake St. Clair Fisheries Research Station
Tel: 586-465-4771 ext. 22
Gary Whelan, Program Manager
MDNR Fisheries Division Research Section
Figure 1. A Lake St. Clair muskellunge bearing the red lesions or sores characteristic of the Piscirickettsia infection.
Figure 2. Electron microscopy image of the Piscirickettsia sp. bacterium isolated from Lake St. Clair muskellunge in 2002.