A virus, most commonly associated with the ornamental Koi fish people raise as pets, was responsible for killing several hundred fish in the St. Joseph River this summer.
The disease — known as Koi herpes virus — had not been found in Indiana previously, but is suspected to be one of the main factors in a kill off of carp in the upper St. Joseph River in Elkhart County this past July, according to the Indiana Department of Natural Resources press release.
Neil Ledet, a fisheries biologist whose district includes St. Joseph and Elkhart counties, said the fish-kill occurred upstream of the Elkhart hydro dam.
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Although he isn’t sure how many fish died — there had been sporadic reports of dead fish for a couple of weeks — Ledet said he saw 200 to 300 floating dead fish when his team investigated.
Tissue samples from the fish were sent to Purdue, where the Koi herpes virus pathogen was discovered.
According to the DNR, the virus and the month’s hot weather — which raised water temperatures and lowered oxygen levels in the river — both contributed to the die off.
Ledet said the Koi herpes virus is more commonly known in the pet world, where the disease is a major concern for breeders of the ornamental fish native to Asia.
But the disease has been showing up increasingly in American waters and wild populations of fish, suspected to be contamination from outdoor Koi ponds or illegal releases of fish into the wild.
The good news, at least to everyone but members of the carp species, is that the virus is not known to harm other fish species. It’s also not dangerous to humans who swim in or who eat fish from the river.
More good news is that despite the discovery in the river, Ledet said there had been no other reports of fish kills along the St. Joseph River this year, a hopeful indication that the disease hasn’t spread very far.
But the bad news, said Ledet, is that there’s now another exotic disease threatening the stability of Indiana’s waters.
“It’s another reminder that you’ve got to think about what your doing,” Ledet said.
The DNR advises boaters to help stop the spread of exotic diseases and species like zebra mussels, by draining, drying and cleaning all boats when moving from one body of water to another. Fishermen should only release fish into the same water from which they were caught.
“People have to have the mindset that they can prevent these things from happening,” Ledet said.
“Hopefully, the virus will run its course and things will stabilize, but its one of those things you just have to wait and see.”
Staff writer Dave Stephens:
Article source: http://www.wsbt.com/news/wsbt-st-joseph-river-fish-kill-blamed-on-new-virus-20111004,0,1699241.story