[Mike]

DNR delves into McDill Pond dead fish mystery

http://www.wisinfo.com/dailytribune/wrdtlocal/288457349948196.shtml

By ANDREW DOWD
For the Daily Tribune
STEVENS POINT – Investigators are not yet sure what killed as many as
a 1,000 fish in McDill Pond over the weekend, but expect an answer to
the oddity within the week.

The sight of dead fish greeted Patrick O’Donnell of Stevens Point on
Monday morning on his daily walk along the shore of McDill Pond in
Koziczkowski Park. As he continued on his walk, the smell hit him.

A neighbor of the pond for almost 26 years, it was the first time he
noticed a large number of bluegills floating belly-up in the water.

“Every once in a while see you’ll see a dead fish, but never anything
like this,” he said.

The Department of Natural Resources launched an investigation Monday
afternoon into the cause of the fish kill.

“Sometimes it’s hard to determine,” said fisheries biologist Tom
Meronek of the Wausau DNR office.
Data and water samples collected by the two DNR employees didn’t
yield a conclusive answer Monday evening, but further testing would
be done Tuesday and testing results are expected back from the state
Department of Hygiene in as little as a week.

Conservation warden from the Whiting DNR Ranger Station Roy Kubisiak
and Meronek spent Monday afternoon on the pond, observing the dead
fish and environmental conditions around them.

“At this point, we see no reason to put any warnings or fish
advisories out at all,” Kubisiak said.

The bluegills were about three to five inches in length and were
found in the pond from the bridge over Business Highway 51 north to
Heffron Street, concentrated in areas with thick aquatic vegetation.

The fish were spread out through the pond, which made estimates of
the dead difficult to make. Meronek said 1,000 or more could be dead
and seen floating on the water or stuck in vegetation along the shore.

The impact on the lake and fishing is expected to be minor, Meronek
said.

“Certainly other areas of the lake with nests are just fine,” he said.

Two probable causes of the kill could be a disease or lack of oxygen
in the water.

When Meronek tested the water’s oxygen content Monday afternoon, he
found it to be supersaturated, which could stress out the fish and
damage their health. He also said aquatic vegetation might be
starving fish of oxygen at night – suffocating them.

Regional fisheries expert Mark Endris of the Department of Natural
Resources office in Eau Claire said fish kills are common this time
of year.

A cause in many cases has been a bacteria called Columnaris, which
primarily affects fish that breed in community nests like bluegills.

Present in many waterways, Endris said the bacteria starts affecting
fish in late May through June when water gets warmer and breeding
begins.

“Usually spawning time is enough to push them over the edge and get
the disease,” Endris said.

Adult bluegills are usually affected by Columnaris, Endris said, and
in the typical kill about 10 percent die from the disease it causes.
When fish use their mouth to pick up pebbles and debris to create
community nests, small wounds become targets for bacteria.

The disease is characterized by a fuzzy look on mouth and tail and
streaks of white along the fish’s back. Gills can become severely
damaged and kill the fish.

McDill Pond hadn’t been chemically treated this year to control
vegetation by the DNR, Meronek said, but a water sample was taken to
test for the concentration of fertilizer chemicals.