Yolk-sac fry undergoing 30 second Bacterin vaccination. (photo: USFWS)

Ron Stone, California-Nevada Fish Health Center
Enteric redmouth disease caused by the bacterium Yersinia ruckeri has affected Fall-run Chinook salmon reared at Coleman National Fish Hatchery for a number of years.  While mortality tends to be moderate, fish must be treated with antibiotics and their disease state interferes with tagging operations. Other than the initial movement of sac-fry from their egg incubators in January to the raceways, there are few opportunities to vaccinate these salmon prior to when outbreaks can occur in early March.  As part of the Coleman Hatchery Evaluation team, the California-Nevada Fish Health Center designed an experiment to examine if yolk-sac fry (alevin) could be vaccinated against the bacterial infection.  Young salmon and trout are typically vaccinated when they are much older. 

Both the vaccinated and control salmon were challenged with live Yersinia ruckeri in the California – Nevada Fish Health Center wet laboratory two months after vaccination with the Yersinia Bacterin.  This facility has biosecurity elements and is used to examine the effects of adverse water quality as well as fish pathogens on fish health issues in California, Nevada, and southern Oregon. We observed no statistical difference in survival of vaccinated to unvaccinated control fish.  It is assumed that the immune systems of the young fish had not developed to the point where they could produce protective antibodies to the bacterium.  While unsuccessful, this effort demonstrates how a Hatchery Evaluation Team can address National Fish Hatchery issues.

The California-Nevada Fish Health Center would like to thank Coleman National Fish Hatchery and its crew, Kurtis Brown, John Silva and Jeff Laurie for their assistance in rearing and maintenance of fish prior to the start of this experiment as well as, conducting each of the Yr. Bacterin applications.  The Fish Health Center would also like to thank Ryan Fogerty for his participation in the wet laboratory during this study.