Iowa River fish species holding their own

Expert doubts any of the lost species will ever return to the Iowa River

Orlan Love
Published: March 24 2014 | 9:22 am - Updated: 1 April 2014 | 10:05 am in

IOWA CITY – The Iowa River still has a surprisingly high percentage of its pre-settlement native fish species, a state water quality specialist told about 40 river lovers gathered here Saturday for a meeting of the Iowa River Friends.

“The number of species has declined, but about 90 percent of native fish species remain in the Iowa River,” John Olson of the Department of Natural Resources watershed monitoring and assessment section said.

Though a high percentage of native species remain, for many of them, their numbers and distribution throughout the river are shrinking, he said.

The middle section of the Iowa River, which includes Iowa City, originally had about 70 fish species, according to Olson. While six of them have since gone missing , “eight are here now that were not originally,” he said.

The six absent species, he said, are the pumpkinseed, rock bass, warmouth, brook silversides, central mudminnow and orange throat darter. The newcomers, mostly unwelcome, are the gizzard shad, freckled madtom, redear sunfish, spotted bass and four species of carp: common, grass, bighead and silver.

Olson said the Iowa River is also home to several species of unusual fish, most of which are found downstream of the Burlington Street dam in Iowa City. They include the American eel, paddlefish, blue sucker, bowfin, shovelnose sturgeon, shortnose gar and northern hog sucker.

Olson said he doubts any of the lost species will ever return to the Iowa River.

Most of them require clear water, aquatic vegetation and backwaters connected to the main channel – conditions that are increasingly rare in Iowa waters, he said.

“For the most part, eating fish from the Iowa River is OK. Subsisting on them might not be,” he said.

Because of the potential for excess levels of mercury, the DNR advises Iowans to eat no more than one meal per week of game fish – bass, walleye and northern pike – from a section of the Iowa River stretching from the dam in Iowa Falls to the upper end of Coralville Lake.

“There’s no problem with eating bottom feeders such as catfish and carp,” Olson said.

While Olson discussed catfish, another DNR biologist, furbearer specialist Vince Evelsizer, updated meeting attendees on the state’s biggest furry cat – the mountain lion.

Since 1995, the DNR has confirmed the presence of 18 mountain lions in the state, most through actual sightings, authenticated trail camera photos and tracks, Evelsizer said.

That contrasts with “sighting reports on a weekly basis,” most of which turn out to be dogs or deer, he said.

The rumor mill, which includes doctored photos distributed on the Internet, would have some believe there is one behind every tree, Evelsizer said..

“Eighteen cats. That’s a fact, the number we have confirmed,” he said.

The DNR has been unable to confirm any of the reported mountain lion sightings in Johnson County, according to Evelsizer. One photo that circulated extensively on the Internet turned out to be a house cat, he said.

Most of the mountain lions visiting Iowa are young males in search of a mate, likely dispersing from the Black Hills of South Dakota, Evelsizer said.

Because most of the state has marginal mountain lion habitat, “it is unlikely that we will ever have a breeding population in Iowa,” he said.

The Iowa River Friends was founded a year ago to promote the enjoyment, protection and improvement of the Iowa River. For more information, visit

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