INDIANAPOLIS, Ind. — With expired federal regulation for a serious fish disease, the Indiana Board of Animal Health (BOAH) has proposed its first rule to specifically protect Indiana aquaculture.
Viral hemorrhagic septicemia, or VHS, is a fatal disease to which most fish species are susceptible, said Dr. Jennifer Strasser, aquaculture veterinarian for BOAH. VHS first showed up in the Great Lakes in 2006, causing hundreds of thousands of fish to die, she said.
Under the proposed state legislation, fish must be tested before permitted into Indiana. Other states around the Great Lakes already have laws in place, Strasser explained last week.
One of the signs of VHS is bloody spots on the fish – but those are indicative of other diseases, as well. A lab must confirm the diagnosis, Strasser said. VHS does not threaten human health because it thrives only within the cooler temperatures of a fish, she added.
It does, however, pose a significant threat to the economic survival of most fisheries should they be contaminated. To date, VHS has not been detected in Indiana’s inland waters, Strasser said. She cautioned continued vigilance.
"We hope it won’t get here. It is still present in the Great Lakes, even though fewer fish are dying. We can’t relax our vigilance. If it infects our water or fish, all populations will see devastating effects," she said.
Strasser further explained Indiana’s fish have not encountered VHS before, so exposure would likely "wipe out all the fish in the facility." The only food fish in Indiana that is not susceptible to VHS is tilapia.
"Different kinds of fish are different species, not breeds. They are like cattle, hogs, chickens, so they can be side by side and affected by different diseases," Strasser explained.
"The vast majority of aquaculture farms in Indiana are cognizant and pay attention to biosecurity. They see the regulations and get new fish tested because they don’t want to bring pathogens onto their farm."
Her greater worry are boaters in the general public who may not empty bilge water from their boats or disinfect outer surfaces when leaving the Great Lakes. She said Indiana’s wild trout are at greatest risk, based on historic trout fatalities and the potential for exposure in rivers and streams.
"Most (aquaculture) facilities are contained, but some use public waters, and those facilities could be at risk, depending on where (contamination) happens," she added.
Since 2005, various fish die-offs attributed to VHS have occurred in Lake Ontario, Lake Erie and Lake St. Clair, according to the BOAH website. They have affected muskellunge, smallmouth bass, yellow perch, bluegill, crappie, gizzard shad, freshwater drum, round goby and others.
VHS has also been detected in samples of walleye, white bass and others that were not part of a die-off.
Strasser said scientists believe the remaining fish in the Great Lakes have developed a degree of immunity to the disease, which may explain why the die-offs have decreased in recent years.