Are Round Goby a Model Species for Studying the Ecology of VHSV in the Wild?

Our initial research efforts examined the status of viral hemorrhagic septicemia virus (VHSV) infections in the wild and the susceptibility of Great Lakes fish species in the laboratory.  We, and others, have shown that VHSV type IVb displays varying levels of pathogenicity in different freshwater species.  Recent research included varying temperature conditions and studying the mechanisms of viral transmission during VHSV challenges.  We have followed shedding of VHSV weekly after injection and immersion challenges with fathead minnows and golden shiners.  We are determining whether feeding infected minnows or zebrafish to a predator fish species (tiger muskellunge) will result in disease transmission.  Although this baseline knowledge is important to establish the risks that VHSV poses to the Great Lakes fish populations, little information is available on dynamics of the pathogen within wild fish communities.  Taking a more direct approach by studying the effects of VHSV in wild populations is the next logical step, and the round goby may be the model species for studying the ecology of VHSV.

In 2006, round goby die-offs in the St. Lawrence River were the first events where significant VHSV-caused mortality was documented in New York.  VHSV surveys in late spring of 2008, 2009, and 2010 showed that VHSV prevalence in round goby has stayed at significant levels, near 52.6% (n=440) in the St. Lawrence River in 2010.  While round goby collected from the St. Lawrence River in fall of 2010 revealed a prevalence of 1.67% (n=180).  Seasonal variations in viral prevalence and limited home range of the round goby during the late spring and summer make this species a candidate for more intensive field studies. 

In 2011 we are sampling round goby in over-wintering locations in deep waters of Lake Ontario to look at fish densities and VHSV prevalence.  We also will begin mark-recapture work with round goby in the St. Lawrence River that will look at incidence, apparent survival, and other factors that drive disease dynamics in the wild while accounting for capture probability.  A non-lethal sampling of fin or gill tissue for VHSV testing is currently being compared with the lethal organ pool sample from our fathead minnow and golden shiner challenges.  This non-lethal technique should allow us to retest recaptured round goby for infection status, which will be key to the research effort.  An overview of our most recent research results will be presented in the context of this ecological approach.