5/5/2006
Weather is responsible for widespread fish kills
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| Drought and unseasonably warm weather have contributed to a larger-than-normal number of spring fish kills reported the Conservation Department this year. (Missouri Dept. of Conservation photo) |
Fish kills around the state are not cause for concern.
JEFFERSON CITY-An unusual number of fish kills across Missouri has some
anglers wondering what the problem is. Fish experts say the answer lies in
the weather. And while fish die-offs are not good news, it is not cause for
serious concern, either.
Resource Scientist Leanna Zweig oversees fish kill investigations for the
Missouri Department of Conservation. She said she routinely receives reports
of fish kills in the spring, but this year has been different.
"Most years, we might get one report of dying fish a week" said Zweig.
"Right now it is more like five a week. They are coming from all over the
state and from every kind of water body-private ponds, big reservoirs,
rivers and creeks."
Zweig says every fish species has been affected, from crappie and largemouth
bass to suckers and shad. Most kills have involved 50 to 100 fish. The
biggest reported so far this year was in the Kings River, a tributary of
Table Rock Lake. The first report came on April 18, and fish continued to
die there for several days.
Conservation Department Fish Pathologist Devona Weirich said that while the
number of fish kills this spring is unusual, the phenomenon itself is
common.
"Fish experience a lot of stress in the spring," said Weirich. "They often
haven't eaten very well during the winter, and they go right into spawning,
which can be exhausting. Their immune systems are very weak, and this
results in some fish dying."
On top of normal stresses, Missouri waters have been affected by an
unusually dry, warm spring. Water temperatures are higher than normal for
this time of year, and water levels in streams and reservoirs is below
normal, especially in southwest Missouri. Water quality is worse than usual,
and fish are crowded into less space. Weirich said it is no wonder a larger
than normal number are succumbing.
In many cases, reports have involved what Zweig called "furry fish," dead
fish with an advanced growth of bacteria or fungus covering their bodies.
She said accurate determination of the cause of death is almost impossible
when decomposition is that far advanced.
Spring fish kills usually happen when external parasites damage fishes' skin
or gills. This leads to a bacterial infection, which kills the animal.
"That is what seems to be going on in all the reports we have received so
far," said Weirich. "We don't have any reason to suspect pollution or other
environmental problems. It's basically natural causes. We simply have a
worse-than-normal case of what we see every spring."
Zweig emphasized that the Conservation Department needs people to report
fish kills as quickly as possible. Fisheries workers can tell much more if
they arrive when fish are still dying than after they are dead.
If you see dead or dying fish, look for unusual conditions, such as odor or
signs of petroleum products on the surface of the water. Also look carefully
at the dead fish before calling the Conservation Department. Zweig said she
investigates several reports each year that turn out to be fish carcasses
discarded by anglers.
To report fish kills, call the nearest Conservation Department office or
contact Zweig directly at
leanna.zweig@mdc.mo.gov, (573) 882-9880, ext. 3228.
-Jim Low-
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