Maryland Whirling Disease

[Rip Tide]

Recent news from the first state to ban felt soles




Whirling disease in trout bought for stocking

ASSOCIATED PRESS
Published 05/20/11

The Maryland Department of Natural Resources said whirling disease has been found in a delivery of 8,000 trout stocked in several western Maryland streams.

The department announced Thursday that DNR staff stopped stocking on May 11 after suspicious behavior was observed in fish being placed in the North Branch Delayed Harvest Area, Evitts Creek, Jennings Run and Sidling Hill Creek.

Tests later confirmed the presence of the parasitic disease, which is not harmful to humans but fatal to trout. The department said it will not accept further shipments from the unidentified vendor until an investigation is completed.

DNR said the disease was first discovered in Maryland in 1995 in the North Branch of the Potomac and that is the only area where it has become established.

[fredaevans]

That IS NOT a good read; any idea where they got the infected fish?

[silver creek]

Maryland is smarter than the Colorado Div of Wildlife. The State of Colorado stocked infected fish for years from it's own infected hatcheries. Maryland also has infected fish hatcheries but the fish are being destroyed "at two facilities in Garrett County"

"Trout from positive hatcheries will be stocked into waters where the parasite has been found to minimize the risk of contaminating other watersheds. Only trout from negative testing hatcheries can be stocked into waters where the parasite has not been found. "

Whirling Disease and Colorado's Trout - Colorado Division of Wildlife

"A disease that attacks the bone structure of young fish has wiped out 90% of Colorado's wild rainbow trout in six of the state's best trout streams, a state study shows. The study by the Colorado Division of Wildlife also found that Whirling disease has reached 12 of the state's 15 trout hatcheries, threatening the state's $420 million-a-year fishing industry."

Whirling disease, trout - USA (Colorado)

Subsequent research showed that parasite dose exposure in the environment increases infection rates and decreases survival. The Colorado Div of Wildlife stocking increased the infection rate.

"Parasite dose strongly determines the severity of whirling disease, which generally increases with the number of triactinomyxons the fish encounters (Hoffman 1974; O’Grodnick 1979; Markiw 1991, 1992a, 1992b; Hedrick et al. 1999a; Thompson et al. 1999; Densmore et al. 2001; Ryce et al. 2001; Ryce et al. 2004; Ryce et al. 2005)."

http://fwpiis.mt.gov/content/getItem.aspx?id=40473

BTW, Whirling Disease has spread beyond the Potomac River basin in Maryland. "Although whirling disease (WD) presence in Maryland was documented as early as 1995, it became a larger issue in early 2007 with the discovery of infected fish at the Bear Creek hatchery in the Youghiogheny River basin. This was the first documentation in Maryland outside of the North Branch Potomac River (NBPR)."

Maryland Department of Natural Resources Fisheries Service

---------- Post added at 04:46 PM ---------- Previous post was at 04:44 PM ----------

Originally Posted by fredaevans

That IS NOT a good read; any idea where they got the infected fish?

Could have been from one of it's own infected hatcheries before the infection was discovered. See my post above.

[fredaevans]

Lordie SC, I'd hope a hatchery would be 'testing the heck' out of their fish stock for this sort of thing. But that wouldn't be the first time I was 'wrong.'

[silver creek]

Unfortunately, as long as the fish act normally, I don't think the fish are routinely tested for WD. There is no reason for the DNR to think the hatchery is infected. Unless a hatchery gets its water by pumping it from underground, they get their water from a stream. If the stream gets infected upstream of the hatchery, then infected water gets into the hatchery and the fish get infected. Or by chance, the hatchery could get infected brood fish from another hatchery. Or hatchery personnel bring in the infection. Until this is found out, those fish get stocked.

With state DNR budgets being so tight, I doubt there is routine testing for WD. Now with several hatcheries infected, I would think all the hatcheries would be tested. The problem is if the water source for the hatchery is infected then you probably have to close the hatchery. I prefer hatcheries to get water from Artesian wells or a capped springs like this one. Bad things can happen to an open water source.