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DEC: Bacteria to blame for ‘significant’ die-off of fish in Seneca Lake

  • / Updated:
  • Staff Report 

The New York State Department of Environmental Conservation (DEC) has identified a common parasite and bacteria as the cause of a significant fish die-off in Seneca Lake last week. After being alerted about the mass mortality on June 20, DEC fisheries staff gathered samples of the Alewife, a prey fish species, from the affected area.


The DEC, in collaboration with the Cornell University College of Veterinary Medicine, determined that Chilodonella, a common parasite found in most waters, and Aeromonas hydrophila, a bacteria causing a disease known as Motile Aeromonas Septicemia in fish, were responsible for the die-off. Importantly, the DEC clarified that neither the parasite nor the bacteria pose any threat to human health.

This incident mirrors a similar die-off in Seneca Lake in 2017, attributed to Chilodonella. No significant impact to the Alewife population has been observed in the wake of the recent event, but the DEC continues to monitor the fishery. The DEC encourages the public to report any instances of fish kill in DEC Region 8 to facilitate timely sample collection and cause determination.