LINCOLN, Neb. (AP) - Thousands of fish are dying in the Midwest as the hot, dry
summer dries up rivers and causes water temperatures to climb in some spots to
nearly 100 degrees.
About 40,000 shovelnose sturgeon were killed in Iowa last
week as water temperatures reached 97 degrees. Nebraska fishery officials said
they've seen thousands of dead sturgeon, catfish, carp, and other species in the
Lower Platte River, including the endangered pallid sturgeon. And biologists in
Illinois said the hot weather has killed tens of thousands of large- and
smallmouth bass and channel catfish and is threatening the population of the
greater redhorse fish, a state-endangered species.
So many fish died in one Illinois lake that the carcasses
clogged an intake screen near a power plant, lowering water levels to the point
that the station had to shut down one of its generators.
"It's something I've never seen in my career, and I've
been here for more than 17 years," said Mark Flammang, a fisheries biologist
with the Iowa Department of Natural Resources. "I think what we're mainly
dealing with here are the extremely low flows and this unparalleled heat."
The fish are victims of one of the driest and warmest
summers in history. The federal U.S. Drought Monitor shows nearly two-thirds of
the lower 48 states are experiencing some form of drought, and the Department of
Agriculture has declared more than half of the nation's counties - nearly 1,600
in 32 states - as natural disaster areas. More than 3,000 heat records were
broken over the last month.
Iowa DNR officials said the sturgeon found dead in the Des
Moines River were worth nearly $10 million, a high value based in part on their
highly sought eggs, which are used for caviar. The fish are valued at more than
$110 a pound.
Gavin Gibbons, a spokesman for the National Fisheries
Institute, said the sturgeon kills don't appear to have reduced the supply
enough to hurt regional caviar suppliers.
Flammang said weekend rain improved some of Iowa's rivers
and lakes, but temperatures were rising again and straining a sturgeon
population that develops health problems when water temperatures climb into the
80s.
"Those fish have been in these rivers for thousands of
thousands of years, and they're accustomed to all sorts of weather conditions,"
he said. "But sometimes, you have conditions occur that are outside their realm
of tolerance."
In Illinois, heat and lack of rain has dried up a large
swath of Aux Sable Creek, the state's largest habitat for the endangered greater
redhorse, a large bottom-feeding fish, said Dan Stephenson, a biologist with the
Illinois Department of Natural Resources.
"We're talking hundreds of thousands (killed), maybe
millions by now," Stephenson said. "If you're only talking about game fish, it's
probably in the thousands. But for all fish, it's probably in the millions if
you look statewide."
Stephenson said fish kills happen most summers in small
private ponds and streams, but the hot weather this year has made the situation
much worse.
"This year has been really, really bad -
disproportionately bad, compared to our other years," he said.
Stephenson said a large number of dead fish were sucked
into an intake screen near Powerton Lake in central Illinois, lowering water
levels and forcing a temporary shutdown at a nearby power plant. A spokesman for
Edison International, which runs the coal-fired plant, said workers shut down
one of its two generators for several hours two weeks ago because of extreme
heat and low water levels at the lake, which is used for cooling.
In Nebraska, a stretch of the Platte River from Kearney in
the central part of the state to Columbus in the east has gone dry and killed a
"significant number" of sturgeon, catfish and minnows, said fisheries program
manager Daryl Bauer. Bauer said the warm, shallow water has also killed an
unknown number of endangered pallid sturgeon.
"It's a lot of miles of river, and a lot of fish," Bauer
said. "Most of those fish are barely identifiable. In this heat, they decay
really fast."
Bauer said a single dry year usually isn't enough to hurt
the fish population. But he worries dry conditions in Nebraska could continue,
repeating a stretch in the mid-2000s that weakened fish populations.
Kansas also has seen declining water levels that pulled
younger, smaller game fish away from the vegetation-rich shore lines and forced
them to cluster, making them easier targets for predators, said fisheries chief
Doug Nygren of the Department of Wildlife, Parks and Tourism.
Nygren said he expects a drop in adult walleye populations
in the state's shallower, wind-swept lakes in southern Kansas. But he said other
species, such as large-mouth bass, can tolerate the heat and may multiply faster
without competition from walleye.
"These last two years are the hottest we've ever seen,"
Nygren said. "That really can play a role in changing populations, shifting it
in favor of some species over others. The walleye won't benefit from these
high-water temperatures, but other species that are more tolerant may take
advantage of their declining population."
Geno Adams, a fisheries program administrator in South
Dakota, said there have been reports of isolated fish kills in its manmade lakes
on the Missouri River and others in the eastern part of the state. But it's
unclear how much of a role the heat played in the deaths.
One large batch of carp at Lewis and Clark Lake in the
state's southeast corner had lesions, a sign they were suffering from a
bacterial infection. Adams said the fish are more prone to sickness with low
water levels and extreme heat. But he added that other fish habitat have seen a
record number this year thanks to the 2011 floods.
"When we're in a drought, there's a struggle for water and
it's going in all different directions," Adams said. "Keeping it in the
reservoir for recreational fisheries is not at the top of the priority
list."
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Dead fish float in a drying pond near Rock Port, Mo, July 26, 2012. (AP Photo/Nati Harnik)
