Thousands of coho salmon eggs (Onchorhyncus kisutch) were recently destroyed at two hatcheries in Wisconsin, USA after testing showed that ovarian fluid taken from ‘donor’ female coho caught in the Root River in Racine, WI, last fall was carrying a reportable infectious virus. The announcement was made by the state’s Department of Natural Resources last December.
Viral Haemorrhagic Septicemia virus (VHSv), first detected in Wisconsin in 2007 is subject to controls designed to protect state hatcheries from contamination. Unfortunately, says the agencies announcement, the positive test results were obtained some time after eggs from the wild-caught fish had been transferred to the Kettle Moraine Springs Hatchery Annex in Sheboygan County and the Les Voigt Hatchery in Bayfield County.
A department spokesperson, Director Ron Bruch, offered reassurance that the infected eggs had undergone the usual disinfection process before being sent to the hatcheries, and there was no risk to either fish or other eggs at the facilities. He said surveillance and biosecurity procedures had long-since been put in place to address just that kind of a scenario, and confirmed that the eggs had been destroyed. He stressed that the virus had not hitherto been detected in the state hatchery system, and added that culling the infected eggs had been fully supported by sports anglers in the area.
“We feel fortunate they [the agency staff] found it [VHSv] and have systems in place to keep it out of the hatcheries,” said Bob Wincek, president of the Milwaukee chapter of Great Lakes Sport Fishing Clubs.
The water- and fish-borne VHS pathogen was first reported in the mid-20th Century in Europe, and is likely to have travelled to North America in ballast tanks of trans-Atlantic ships.