Thought you aquaculture watchers might be interested in this. For the
aquaculture connection, see the moderator's note at the end.
pax
m
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COLUMNARIS, WHITE BASS - USA (KANSAS)
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A ProMED-mail post
Date: Fri, 09 Jul 1999 23:21:00 -0400
From: Marjorie P. Pollack
Source: The Wichita Eagle, 9 Jul 1999 [edited]
Columnaris disease, due to _Flavobacterium columnare_, has killed an
estimated 48,000 white bass at Melvern Reservoir. Several weeks ago, some
6,000 white bass also fell victim to columnaris disease at Pomona Reservoir.
Leonard Jirak, district fisheries biologist for Melvern and Pomona, said
that the bacteria is always present in reservoirs, adding that it increases
and decreases in density for a variety of reasons that include water
temperature, decomposing nutrients, sunlight and lack of oxygen. Those and
other factors can trigger an outbreak. The bacteria affects the gill
filaments of fish and white bass -- a schooling fish -- appear to be more
susceptible based on the species-specific fish kills at Melvern and Pomona,
and the 80,000 white bass that died at Cheney Reservoir in 1998.
Jirak speculates that the fish kill at Melvern has run its course, but he's
not counting all his fish until they've surfaced. "There were more dead
ones two days ago than there were today and that tells me that it's past
its peak, but it's not done," Jirak said.
Steve Adams is the fish kill coordinator for Wildlife and Parks. From his
perspective, it's too early to make a call on just what may have triggered
the increase in the bacteria. "Logically, you would think that there's a
stress that occurs, whether it's a sudden rise in temperature or an inflow
of something," Adams said. "I talked with the folks at KDHE (Kansas
Department of Health and Environment) and at this point I'm not aware of
any unusual water quality results." Adams said that scientific studies of
white bass have shown the species to be more susceptible to gill-related
diseases. "It's not unusual for it to happen," Adams said. "It's a shame,
but at this point we've just got to let it run it's course."
[Byline: Steve Harper]
- --
ProMED-mail
[Columnaris disease is the second leading cause of mortality in pond raised
catfish in the SE USA. It is second only to enteric septicaemia of catfish,
caused by _Edwardsiella ictaluri_. Most species of fish are susceptible to
columnaris disease following some type of environmental stress and when
water temperatures are in the upper part of their preferred temperature
range. The disease commonly occurs in channel catfish when the water
temperatures are in the range of 25'C to 32'C or 77'F to 90'F in the
spring, summer & fall. Schooling species of fish, like white bass, are
especially susceptible.
Fish with this disease usually have yellowish-brown lesions on their gills.
These lesions result in the erosion of the gills by protein- and
cartilage-degrading enzymes produced by the bacteria. Skin ("saddleback")
lesions can be noted encircling the body of fingerlings; as well as lesions
inside the fish's mouth. _F. columnare_ can also be isolated from internal
organs (for example in a study in Mississippi, 40% of fish with external
lesions had isolations from internal organs) but the significance is
uncertain. Swelling of the posterior kidney has been noted. - MHJ]
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Communications manager
Center for Integrated Ag Systems, UW-Madison
http://www.wisc.edu
UW voice mail: 608-262-8018
Home office: 415-504-6474 (504-MISH)
Home office fax: Same as above, phone first for enabling
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