Majority of native fish species remain, but in declining numbers

While a high percentage of native species remains, numbers and distribution along Iowa River are shrinking

Orlan Love
Published: March 23 2014 | 9:49 am - Updated: 1 April 2014 | 10:03 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 said.

Though a high percentage of native species remains, 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 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 also is 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 the lost species will 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 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 people thinking there is one behind every tree, Evelsizer said.

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

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